Inhibitory effects of selected cannabinoids against dipeptidyl peptidase IV, an enzyme linked to type 2 diabetes
- Mkabayi, Lithalethu, Viljoen, Zenobia, Krause, Rui W M, Lobb, Kevin A, Pletschke, Brett I, Frost, Carminita L
- Authors: Mkabayi, Lithalethu , Viljoen, Zenobia , Krause, Rui W M , Lobb, Kevin A , Pletschke, Brett I , Frost, Carminita L
- Date: 2024
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452760 , vital:75168 , xlink:href="https://doi.org/10.1016/j.heliyon.2023.e23289"
- Description: Ethnopharmacological relevance: In recent times the decriminalisation of cannabis globally has increased its use as an alternative medication. Where it has been used in modern medicinal practises since the 1800s, there is limited scientific investigation to understand the biological activities of this plant. Aim of the study: Dipeptidyl peptidase IV (DPP-IV) plays a key role in regulating glucose homeostasis, and inhibition of this enzyme has been used as a therapeutic approach to treat type 2 diabetes. However, some of the synthetic inhibitors for this enzyme available on the market may cause undesirable side effects. Therefore, it is important to identify new inhibitors of DPP-IV and to understand their interaction with this enzyme.
- Full Text:
- Date Issued: 2024
- Authors: Mkabayi, Lithalethu , Viljoen, Zenobia , Krause, Rui W M , Lobb, Kevin A , Pletschke, Brett I , Frost, Carminita L
- Date: 2024
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452760 , vital:75168 , xlink:href="https://doi.org/10.1016/j.heliyon.2023.e23289"
- Description: Ethnopharmacological relevance: In recent times the decriminalisation of cannabis globally has increased its use as an alternative medication. Where it has been used in modern medicinal practises since the 1800s, there is limited scientific investigation to understand the biological activities of this plant. Aim of the study: Dipeptidyl peptidase IV (DPP-IV) plays a key role in regulating glucose homeostasis, and inhibition of this enzyme has been used as a therapeutic approach to treat type 2 diabetes. However, some of the synthetic inhibitors for this enzyme available on the market may cause undesirable side effects. Therefore, it is important to identify new inhibitors of DPP-IV and to understand their interaction with this enzyme.
- Full Text:
- Date Issued: 2024
Inhibiting human dipeptidyl peptidase IV using cannabinoids and Leonotis leonurus extracts as a potential therapy for the management of diabetes
- Mkabayi, Lithalethu, Viljoen, Zenobia, Lobb, Kevin A, Pletschke, Brett I, Frost, Carminita L
- Authors: Mkabayi, Lithalethu , Viljoen, Zenobia , Lobb, Kevin A , Pletschke, Brett I , Frost, Carminita L
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452745 , vital:75167 , xlink:href="https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0043-1773924"
- Description: Diabetes is a chronic metabolic disorder that has been shown to affect a growing number of people worldwide. Controlling blood glucose levels is one of the possible strategies to treat type 2 diabetes mellitus (T2DM). It has been established that the inhibition of dipeptidyl peptidase IV (DPP-IV) prolongs the activity of incretin hormones, which serve as key stimulators of insulin secretion and regulation of blood glucose levels. Although several synthetic DPP-IV inhibitors are available, there is still a need for naturally sourced inhibitors that have fewer to no undesirable side effects. In this study, cannabinoids and Leonotis leonurus aqueous extracts were evaluated for their inhibitory effects against recombinant human DPP-IV. Their potential inhibition mechanism was explored using in vitro and in silico approaches. All tested cannabinoids and L. leonurus aqueous extracts showed significant inhibitory activity against DPP-IV. Phytochemical analysis of L. leonurus extract indicated the presence of diterpenoids and alkaloids, which might contribute to the inhibitory activity. In molecular docking studies, among different constituents known in L. leonurus, luteolin and marrubiin showed binding energy of -7.2 kcal/mol and cannabinoids (cannabidiol, cannabigerol, cannabinol and Δ9-tetrahydrocannabinol) showed binding energies ranging from -6.5 to -8.2 kcal/mol. Molecular dynamics revealed that all tested compounds formed stable complexes with the enzyme during 100 ns simulation, indicating that they are good ligands. This study provided preliminary evidence for the potential application of the selected cannabinoids and L. leonurus in maintaining glucose homeostasis, suggesting that they could be suitable therapeutic candidates for managing T2DM.
- Full Text:
- Date Issued: 2023
- Authors: Mkabayi, Lithalethu , Viljoen, Zenobia , Lobb, Kevin A , Pletschke, Brett I , Frost, Carminita L
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452745 , vital:75167 , xlink:href="https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0043-1773924"
- Description: Diabetes is a chronic metabolic disorder that has been shown to affect a growing number of people worldwide. Controlling blood glucose levels is one of the possible strategies to treat type 2 diabetes mellitus (T2DM). It has been established that the inhibition of dipeptidyl peptidase IV (DPP-IV) prolongs the activity of incretin hormones, which serve as key stimulators of insulin secretion and regulation of blood glucose levels. Although several synthetic DPP-IV inhibitors are available, there is still a need for naturally sourced inhibitors that have fewer to no undesirable side effects. In this study, cannabinoids and Leonotis leonurus aqueous extracts were evaluated for their inhibitory effects against recombinant human DPP-IV. Their potential inhibition mechanism was explored using in vitro and in silico approaches. All tested cannabinoids and L. leonurus aqueous extracts showed significant inhibitory activity against DPP-IV. Phytochemical analysis of L. leonurus extract indicated the presence of diterpenoids and alkaloids, which might contribute to the inhibitory activity. In molecular docking studies, among different constituents known in L. leonurus, luteolin and marrubiin showed binding energy of -7.2 kcal/mol and cannabinoids (cannabidiol, cannabigerol, cannabinol and Δ9-tetrahydrocannabinol) showed binding energies ranging from -6.5 to -8.2 kcal/mol. Molecular dynamics revealed that all tested compounds formed stable complexes with the enzyme during 100 ns simulation, indicating that they are good ligands. This study provided preliminary evidence for the potential application of the selected cannabinoids and L. leonurus in maintaining glucose homeostasis, suggesting that they could be suitable therapeutic candidates for managing T2DM.
- Full Text:
- Date Issued: 2023
Interaction of silver nanoparticles with catechol O-methyltransferase: Spectroscopic and simulation analyses
- Usman, Aminu, Lobb, Kevin A, Pletschke, Brett I, Whiteley, Christopher G, Wilhelmi, Brendan S
- Authors: Usman, Aminu , Lobb, Kevin A , Pletschke, Brett I , Whiteley, Christopher G , Wilhelmi, Brendan S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451095 , vital:75018 , xlink:href=" https://doi.org/10.1016/j.bbrep.2021.101013"
- Description: Catechol O-methyltransferase, an enzyme involved in the metabolism of catechol containing compounds, catalyzes the transfer of a methyl group between S-adenosylmethionine and the hydroxyl groups of the catechol. Furthermore it is considered a potential drug target for Parkinson’s disease as it metabolizes the drug levodopa. Consequently inhibitors of the enzyme would increase levels of levodopa. In this study, absorption, fluorescence and infrared spectroscopy as well as computational simulation studies investigated human soluble catechol Omethyltransferase interaction with silver nanoparticles. The nanoparticles form a corona with the enzyme and quenches the fluorescence of Trp143. This amino acid maintains the correct structural orientation for the catechol ring during catalysis through a static mechanism supported by a non-fluorescent fluorophore–nanoparticle complex. The enzyme has one binding site for AgNPs in a thermodynamically spontaneous binding driven by electrostatic interactions as confirmed by negative ΔG and ΔH and positive ΔS values. Fourier transform infrared spectroscopy within the amide I region of the enzyme indicated that the interaction causes relaxation of its β− structures, while simulation studies indicated the involvement of six polar amino acids. These findings suggest AgNPs influence the catalytic activity of catechol O-methyltransferase, and therefore have potential in controlling the activity of the enzyme.
- Full Text:
- Date Issued: 2021
- Authors: Usman, Aminu , Lobb, Kevin A , Pletschke, Brett I , Whiteley, Christopher G , Wilhelmi, Brendan S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451095 , vital:75018 , xlink:href=" https://doi.org/10.1016/j.bbrep.2021.101013"
- Description: Catechol O-methyltransferase, an enzyme involved in the metabolism of catechol containing compounds, catalyzes the transfer of a methyl group between S-adenosylmethionine and the hydroxyl groups of the catechol. Furthermore it is considered a potential drug target for Parkinson’s disease as it metabolizes the drug levodopa. Consequently inhibitors of the enzyme would increase levels of levodopa. In this study, absorption, fluorescence and infrared spectroscopy as well as computational simulation studies investigated human soluble catechol Omethyltransferase interaction with silver nanoparticles. The nanoparticles form a corona with the enzyme and quenches the fluorescence of Trp143. This amino acid maintains the correct structural orientation for the catechol ring during catalysis through a static mechanism supported by a non-fluorescent fluorophore–nanoparticle complex. The enzyme has one binding site for AgNPs in a thermodynamically spontaneous binding driven by electrostatic interactions as confirmed by negative ΔG and ΔH and positive ΔS values. Fourier transform infrared spectroscopy within the amide I region of the enzyme indicated that the interaction causes relaxation of its β− structures, while simulation studies indicated the involvement of six polar amino acids. These findings suggest AgNPs influence the catalytic activity of catechol O-methyltransferase, and therefore have potential in controlling the activity of the enzyme.
- Full Text:
- Date Issued: 2021
Partial Purification and Characterization of Endoxylanase from a fungus, Leohumicola incrustata
- Adeoyo, Olusegun R, Pletschke, Brett I, Dames, Joanna F
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440393 , vital:73779 , 10.4314/br.v19i1.2
- Description: Xylanases are glycoside hydrolases (GH) that degrade β-1, 4-xylan, a linear polysaccharide found as hemicellulose in cell wall of plants. Endoxylanase (Endo-1, 4-β-xylanase, EC 3.2. 1.8) randomly catalyses xylan to produce varying short xylooligosaccharides (XOS). This study aimed to determine the characteristics of a partially purified endoxylanase from Leohumicola incrustata. Enzyme production was carried out using beechwood (BW) xylan, after which the cell-free crude filtrate was concentrated using the ammonium sulphate precipitation method. The hydrolysed products were analysed by thin-layer chromatography (TLC) and zymography. The result showed that the enzyme produced varying smaller-sized linear xylooligosaccharides with R f values corresponding to those of xylobiose, xylotriose, xylotetraose, xylopentaose, xylohexaose and other higher oligomers. The endoxylanase had a molecular mass of 72 kDa. The enzyme is stable in the presence of K+, Na+, Ca 2+, Fe 2+, Mg 2+, Zn 2+, Co 2+, pH of 5.0 and temperature of 37 o C. However, the activity gradually decreased after 60 min at 50 o C and retained over 69% activity after 120 min, while at 60 and 70 o C, the enzyme activity sharply decreased (pre-incubation periods). Endoxylanase from L. incrustata is comparable to those of other microorganisms and should be considered an attractive candidate for future industrial applications.
- Full Text:
- Date Issued: 2021
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440393 , vital:73779 , 10.4314/br.v19i1.2
- Description: Xylanases are glycoside hydrolases (GH) that degrade β-1, 4-xylan, a linear polysaccharide found as hemicellulose in cell wall of plants. Endoxylanase (Endo-1, 4-β-xylanase, EC 3.2. 1.8) randomly catalyses xylan to produce varying short xylooligosaccharides (XOS). This study aimed to determine the characteristics of a partially purified endoxylanase from Leohumicola incrustata. Enzyme production was carried out using beechwood (BW) xylan, after which the cell-free crude filtrate was concentrated using the ammonium sulphate precipitation method. The hydrolysed products were analysed by thin-layer chromatography (TLC) and zymography. The result showed that the enzyme produced varying smaller-sized linear xylooligosaccharides with R f values corresponding to those of xylobiose, xylotriose, xylotetraose, xylopentaose, xylohexaose and other higher oligomers. The endoxylanase had a molecular mass of 72 kDa. The enzyme is stable in the presence of K+, Na+, Ca 2+, Fe 2+, Mg 2+, Zn 2+, Co 2+, pH of 5.0 and temperature of 37 o C. However, the activity gradually decreased after 60 min at 50 o C and retained over 69% activity after 120 min, while at 60 and 70 o C, the enzyme activity sharply decreased (pre-incubation periods). Endoxylanase from L. incrustata is comparable to those of other microorganisms and should be considered an attractive candidate for future industrial applications.
- Full Text:
- Date Issued: 2021
A novel dimeric exoglucanase (GH5_38)
- Mafa, Mpho S, Dirr, Heinrich W, Malgas, Samkelo, Krause, Rui W M, Pletschke, Brett I
- Authors: Mafa, Mpho S , Dirr, Heinrich W , Malgas, Samkelo , Krause, Rui W M , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193976 , vital:45412 , xlink:href="https://doi.org/10.3390/molecules25030746"
- Description: An exoglucanase (Exg-D) from the glycoside hydrolase family 5 subfamily 38 (GH5_38) was heterologously expressed and structurally and biochemically characterised at a molecular level for its application in alkyl glycoside synthesis. The purified Exg-D existed in both dimeric and monomeric forms in solution, which showed highest activity on mixed-linked β-glucan (88.0 and 86.7 U/mg protein, respectively) and lichenin (24.5 and 23.7 U/mg protein, respectively). They displayed a broad optimum pH range from 5.5 to 7 and a temperature optimum from 40 to 60 °C. Kinetic studies demonstrated that Exg-D had a higher affinity towards β-glucan, with a Km of 7.9 mg/mL and a kcat of 117.2 s−1, compared to lichenin which had a Km of 21.5 mg/mL and a kcat of 70.0 s−1. The circular dichroism profile of Exg-D showed that its secondary structure consisted of 11% α-helices, 36% β-strands and 53% coils. Exg-D performed transglycosylation using p-nitrophenyl cellobioside as a glycosyl donor and several primary alcohols as acceptors to produce methyl-, ethyl- and propyl-cellobiosides. These products were identified and quantified via thin-layer chromatography (TLC) and liquid chromatography–mass spectrometry (LC-MS). We concluded that Exg-D is a novel and promising oligomeric glycoside hydrolase for the one-step synthesis of alkyl glycosides with more than one monosaccharide unit.
- Full Text:
- Date Issued: 2020
- Authors: Mafa, Mpho S , Dirr, Heinrich W , Malgas, Samkelo , Krause, Rui W M , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193976 , vital:45412 , xlink:href="https://doi.org/10.3390/molecules25030746"
- Description: An exoglucanase (Exg-D) from the glycoside hydrolase family 5 subfamily 38 (GH5_38) was heterologously expressed and structurally and biochemically characterised at a molecular level for its application in alkyl glycoside synthesis. The purified Exg-D existed in both dimeric and monomeric forms in solution, which showed highest activity on mixed-linked β-glucan (88.0 and 86.7 U/mg protein, respectively) and lichenin (24.5 and 23.7 U/mg protein, respectively). They displayed a broad optimum pH range from 5.5 to 7 and a temperature optimum from 40 to 60 °C. Kinetic studies demonstrated that Exg-D had a higher affinity towards β-glucan, with a Km of 7.9 mg/mL and a kcat of 117.2 s−1, compared to lichenin which had a Km of 21.5 mg/mL and a kcat of 70.0 s−1. The circular dichroism profile of Exg-D showed that its secondary structure consisted of 11% α-helices, 36% β-strands and 53% coils. Exg-D performed transglycosylation using p-nitrophenyl cellobioside as a glycosyl donor and several primary alcohols as acceptors to produce methyl-, ethyl- and propyl-cellobiosides. These products were identified and quantified via thin-layer chromatography (TLC) and liquid chromatography–mass spectrometry (LC-MS). We concluded that Exg-D is a novel and promising oligomeric glycoside hydrolase for the one-step synthesis of alkyl glycosides with more than one monosaccharide unit.
- Full Text:
- Date Issued: 2020
Combination of CTec2 and GH5 or GH26 Endo-Mannanases for Effective Lignocellulosic Biomass Degradation
- Malgas, Samkelo, Pletschke, Brett I
- Authors: Malgas, Samkelo , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429397 , vital:72607 , xlink:href="https://doi.org/10.3390/catal10101193"
- Description: Among endo-mannanases, glycoside hydrolase (GH) family 26 enzymes have been shown to be more catalytically active than GH5 enzymes on mannans. However, only GH5 endo-mannanases have been used for the formulation of enzyme cocktails. In this study, Bacillus sp.-derived GH5 and GH26 endo-mannanases were comparatively analysed biochemically for their synergistic action with a commercial cellulase blend, CTec2, during pre-treated lignocellulose degradation. Substrate specificity and thermo-stability studies on mannan substrates showed that GH26 endo-mannanase was more catalytically active and stable than GH5. GH26 also exhibited higher binding affinity for mannan than GH5, while GH5 showed more affinity for lignocellulosic substrates than GH26. Applying the endo-mannanases in combination with CTec2 for lignocellulose degradation led to synergism with a 1.3-fold increase in reducing sugar release compared to when CTec2 was used alone. This study showed that using the activity of endo-mannanases displayed with model substrates is a poor predictor of their activity and synergism on complex lignocelluloses.
- Full Text:
- Date Issued: 2020
- Authors: Malgas, Samkelo , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429397 , vital:72607 , xlink:href="https://doi.org/10.3390/catal10101193"
- Description: Among endo-mannanases, glycoside hydrolase (GH) family 26 enzymes have been shown to be more catalytically active than GH5 enzymes on mannans. However, only GH5 endo-mannanases have been used for the formulation of enzyme cocktails. In this study, Bacillus sp.-derived GH5 and GH26 endo-mannanases were comparatively analysed biochemically for their synergistic action with a commercial cellulase blend, CTec2, during pre-treated lignocellulose degradation. Substrate specificity and thermo-stability studies on mannan substrates showed that GH26 endo-mannanase was more catalytically active and stable than GH5. GH26 also exhibited higher binding affinity for mannan than GH5, while GH5 showed more affinity for lignocellulosic substrates than GH26. Applying the endo-mannanases in combination with CTec2 for lignocellulose degradation led to synergism with a 1.3-fold increase in reducing sugar release compared to when CTec2 was used alone. This study showed that using the activity of endo-mannanases displayed with model substrates is a poor predictor of their activity and synergism on complex lignocelluloses.
- Full Text:
- Date Issued: 2020
Delineating functional properties of a cello-oligosaccharide and Bglucan specific cellobiohydrolase (GH5_38): Its synergism with Cel6A and Cel7A for B-(1,3)-(1,4)-glucan degradation
- Mafa, Mpho S, Malgas, Samkelo, Rashamuse, Konanani, Pletschke, Brett I
- Authors: Mafa, Mpho S , Malgas, Samkelo , Rashamuse, Konanani , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429425 , vital:72609 , xlink:href="https://doi.org/10.1016/j.carres.2020.108081"
- Description: Cellulase cocktails formulated to degrade crystalline cellulose generally contain cellobiohydrolases (CBHs), referred to as CBHI (Cel7A) and CBHII (Cel6A), as the major constituents. The combined hydrolytic activities of CBHI and CBHII improve the release of fermentable sugars (β-1,4-cellobiose as the main product) from crystalline cellulose. In this study, a novel cellobiohydrolase (Exg-D) sourced from a metagenome of hindgut bacterial symbionts of a termite was heterologouly expressed, purified, and functionally characterised. Exg-D specific activity was higher on insoluble barley β-glucan (38.94 U/mg protein), soluble wheat flour β-glucan (12.71 U/mg protein) and oat β-glucan (8.89 U/mg protein) compared to cellulosic substrates; Avicel and CMC. We further explored Exg-D activity on the unpretreated or NaOH-pretreated (mercerised) Avicel and compared its activity to commercially available CBHI and CBHII on these celluloses. CBHI displayed the highest activity of 4.74 U/mg protein on mercerised cellulose followed by CBHII (2.14 U/mg protein), while Exg-D activity on untreated and mercerised cellulose was 1.66 and 1.67 U/mg protein, respectively. The high activity of CBHI was supported by binding assays, which revealed that CBHI has a higher binding capacity towards crystalline cellulose compared to Exg-D and CBHII. Only CBHI and CBHII showed synergism during the hydrolysis of mercerised Avicel, showing a degree of synergy (DS) of about 1.299 and yielded about 1.43 μmol/ml of reducing sugars higher than control. In contrast, Exg-D and CBHII displayed synergism during β-glucan degradation, displaying a DS of about 1.22. Thus, we propose that Exg-D should only be used synergistically with other CBHs to degrade mixed linked-β-(1,3)-(1,4)-glucan.
- Full Text:
- Date Issued: 2020
- Authors: Mafa, Mpho S , Malgas, Samkelo , Rashamuse, Konanani , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429425 , vital:72609 , xlink:href="https://doi.org/10.1016/j.carres.2020.108081"
- Description: Cellulase cocktails formulated to degrade crystalline cellulose generally contain cellobiohydrolases (CBHs), referred to as CBHI (Cel7A) and CBHII (Cel6A), as the major constituents. The combined hydrolytic activities of CBHI and CBHII improve the release of fermentable sugars (β-1,4-cellobiose as the main product) from crystalline cellulose. In this study, a novel cellobiohydrolase (Exg-D) sourced from a metagenome of hindgut bacterial symbionts of a termite was heterologouly expressed, purified, and functionally characterised. Exg-D specific activity was higher on insoluble barley β-glucan (38.94 U/mg protein), soluble wheat flour β-glucan (12.71 U/mg protein) and oat β-glucan (8.89 U/mg protein) compared to cellulosic substrates; Avicel and CMC. We further explored Exg-D activity on the unpretreated or NaOH-pretreated (mercerised) Avicel and compared its activity to commercially available CBHI and CBHII on these celluloses. CBHI displayed the highest activity of 4.74 U/mg protein on mercerised cellulose followed by CBHII (2.14 U/mg protein), while Exg-D activity on untreated and mercerised cellulose was 1.66 and 1.67 U/mg protein, respectively. The high activity of CBHI was supported by binding assays, which revealed that CBHI has a higher binding capacity towards crystalline cellulose compared to Exg-D and CBHII. Only CBHI and CBHII showed synergism during the hydrolysis of mercerised Avicel, showing a degree of synergy (DS) of about 1.299 and yielded about 1.43 μmol/ml of reducing sugars higher than control. In contrast, Exg-D and CBHII displayed synergism during β-glucan degradation, displaying a DS of about 1.22. Thus, we propose that Exg-D should only be used synergistically with other CBHs to degrade mixed linked-β-(1,3)-(1,4)-glucan.
- Full Text:
- Date Issued: 2020
Evaluating Feruloyl Esterase—Xylanase Synergism for Hydroxycinnamic Acid and Xylo-Oligosaccharide Production from Untreated, Hydrothermally Pre-Treated and Dilute-Acid Pre-Treated Corn Cobs:
- Mkabayi, Lithalethu, Malgas, Samkelo, Wilhelmi, Brendan S, Pletschke, Brett I
- Authors: Mkabayi, Lithalethu , Malgas, Samkelo , Wilhelmi, Brendan S , Pletschke, Brett I
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149240 , vital:38818 , https://doi.org/10.3390/agronomy10050688
- Description: Agricultural residues are considered the most promising option as a renewable feedstock for biofuel and high valued-added chemical production due to their availability and low cost. The efficient enzymatic hydrolysis of agricultural residues into value-added products such as sugars and hydroxycinnamic acids is a challenge because of the recalcitrant properties of the native biomass. Development of synergistic enzyme cocktails is required to overcome biomass residue recalcitrance, and achieve high yields of potential value-added products. In this study, the synergistic action of two termite metagenome-derived feruloyl esterases (FAE5 and FAE6), and an endo-xylanase (Xyn11) from Thermomyces lanuginosus, was optimized using 0.5% (w/v) insoluble wheat arabinoxylan (a model substrate) and then applied to 1% (w/v) corn cobs for the efficient production of xylo-oligosaccharides (XOS) and hydroxycinnamic acids.
- Full Text:
- Date Issued: 2020
- Authors: Mkabayi, Lithalethu , Malgas, Samkelo , Wilhelmi, Brendan S , Pletschke, Brett I
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149240 , vital:38818 , https://doi.org/10.3390/agronomy10050688
- Description: Agricultural residues are considered the most promising option as a renewable feedstock for biofuel and high valued-added chemical production due to their availability and low cost. The efficient enzymatic hydrolysis of agricultural residues into value-added products such as sugars and hydroxycinnamic acids is a challenge because of the recalcitrant properties of the native biomass. Development of synergistic enzyme cocktails is required to overcome biomass residue recalcitrance, and achieve high yields of potential value-added products. In this study, the synergistic action of two termite metagenome-derived feruloyl esterases (FAE5 and FAE6), and an endo-xylanase (Xyn11) from Thermomyces lanuginosus, was optimized using 0.5% (w/v) insoluble wheat arabinoxylan (a model substrate) and then applied to 1% (w/v) corn cobs for the efficient production of xylo-oligosaccharides (XOS) and hydroxycinnamic acids.
- Full Text:
- Date Issued: 2020
Fucoidan from Ecklonia maxima is a powerful inhibitor of the diabetes-related enzyme, Éø-glucosidase
- Daub, Chantal D, Mabate, Blessing, Malgas, Samkelo, Pletschke, Brett I
- Authors: Daub, Chantal D , Mabate, Blessing , Malgas, Samkelo , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425982 , vital:72304 , xlink:href="https://doi.org/10.1016/j.ijbiomac.2020.02.161"
- Description: Ecklonia maxima, an endemic South African seaweed, is a potential source of beneficial bioactive compounds. Among these compounds, fucoidan, a sulphated polysaccharide has a wide range of bioactivities including anti-diabetic activity. In this study, fucoidan was extracted from E. maxima by the hot water extraction method and then characterised by colorimetric assays for sugar composition. The extraction from E. maxima yielded 6.89% fucoidan which was found to contain 4.45 ± 0.25% L-fucose and 6.01 ± 0.53% sulphate. The water extracted E. maxima fucoidan had a low molecular weight of approximately 10 kDa. Structural studies (FT-IR, NMR and XRD) confirmed the structure and integrity of the fucoidan to be similar to previously studied fucoidans in literature. Finally, the activities of starch digestive enzymes; α-amylase and α-glucosidase, were investigated in the presence of the E. maxima fucoidan extract. Fucoidan from E. maxima was observed to be a potent mixed-type inhibitor of α-glucosidase with an IC50 range of 0.27–0.31 mg.ml-1, which was significantly lower than the commercial anti-diabetic standard, acarbose. Our present study demonstrated that fucoidan from E. maxima is a more powerful inhibitor compared to some standard anti-diabetic compounds and thus shows great potential for managing type 2 diabetes.
- Full Text:
- Date Issued: 2020
Fucoidan from Ecklonia maxima is a powerful inhibitor of the diabetes-related enzyme, Éø-glucosidase
- Authors: Daub, Chantal D , Mabate, Blessing , Malgas, Samkelo , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425982 , vital:72304 , xlink:href="https://doi.org/10.1016/j.ijbiomac.2020.02.161"
- Description: Ecklonia maxima, an endemic South African seaweed, is a potential source of beneficial bioactive compounds. Among these compounds, fucoidan, a sulphated polysaccharide has a wide range of bioactivities including anti-diabetic activity. In this study, fucoidan was extracted from E. maxima by the hot water extraction method and then characterised by colorimetric assays for sugar composition. The extraction from E. maxima yielded 6.89% fucoidan which was found to contain 4.45 ± 0.25% L-fucose and 6.01 ± 0.53% sulphate. The water extracted E. maxima fucoidan had a low molecular weight of approximately 10 kDa. Structural studies (FT-IR, NMR and XRD) confirmed the structure and integrity of the fucoidan to be similar to previously studied fucoidans in literature. Finally, the activities of starch digestive enzymes; α-amylase and α-glucosidase, were investigated in the presence of the E. maxima fucoidan extract. Fucoidan from E. maxima was observed to be a potent mixed-type inhibitor of α-glucosidase with an IC50 range of 0.27–0.31 mg.ml-1, which was significantly lower than the commercial anti-diabetic standard, acarbose. Our present study demonstrated that fucoidan from E. maxima is a more powerful inhibitor compared to some standard anti-diabetic compounds and thus shows great potential for managing type 2 diabetes.
- Full Text:
- Date Issued: 2020
The Effects of Alkaline Pretreatment on Agricultural Biomasses (Corn Cob and Sweet Sorghum Bagasse) and Their Hydrolysis by a Termite-Derived Enzyme Cocktail:
- Mafa, Mpho S, Malgas, Samkelo, Bhattacharya, Abhishek, Rashamuse, Konanani, Pletschke, Brett I
- Authors: Mafa, Mpho S , Malgas, Samkelo , Bhattacharya, Abhishek , Rashamuse, Konanani , Pletschke, Brett I
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160273 , vital:40430 , https://doi.org/10.3390/agronomy10081211
- Description: Sweet sorghum bagasse (SSB) and corncob (CC) have been identified as promising feedstocks for the production of second-generation biofuels and other value-added chemicals. In this study, lime (Ca(OH)2) and NaOH pretreatment efficacy for decreasing recalcitrance from SSB and CC was investigated, and subsequently, the pretreated biomass was subjected to the hydrolytic action of an in-house formulated holocellulolytic enzyme cocktail (HEC-H). Compositional analysis revealed that SSB contained 29.34% lignin, 17.75% cellulose and 16.28% hemicellulose, while CC consisted of 22.51% lignin, 23.58% cellulose and 33.34% hemicellulose. Alkaline pretreatment was more effective in pretreating CC biomass compared to the SSB biomass.
- Full Text:
- Date Issued: 2020
- Authors: Mafa, Mpho S , Malgas, Samkelo , Bhattacharya, Abhishek , Rashamuse, Konanani , Pletschke, Brett I
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160273 , vital:40430 , https://doi.org/10.3390/agronomy10081211
- Description: Sweet sorghum bagasse (SSB) and corncob (CC) have been identified as promising feedstocks for the production of second-generation biofuels and other value-added chemicals. In this study, lime (Ca(OH)2) and NaOH pretreatment efficacy for decreasing recalcitrance from SSB and CC was investigated, and subsequently, the pretreated biomass was subjected to the hydrolytic action of an in-house formulated holocellulolytic enzyme cocktail (HEC-H). Compositional analysis revealed that SSB contained 29.34% lignin, 17.75% cellulose and 16.28% hemicellulose, while CC consisted of 22.51% lignin, 23.58% cellulose and 33.34% hemicellulose. Alkaline pretreatment was more effective in pretreating CC biomass compared to the SSB biomass.
- Full Text:
- Date Issued: 2020
Molecular identification and antibacterial properties of an ericoid associated mycorrhizal fungus
- Adeoyo, Olusegun R, Pletschke, Brett I, Dames, Joanna F
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440378 , vital:73778 , https://doi.org/10.1186/s12866-019-1555-y
- Description: The quest for novel sources of antibacterial compounds have necessitated the inclusion of ericoid mycorrhizal fungi (ERM) commonly found within the root of ericaceous plants. Agar-well diffusion method was used to detect antibacterial activity and was followed by the microbroth diffusion method [minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)].
- Full Text:
- Date Issued: 2019
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440378 , vital:73778 , https://doi.org/10.1186/s12866-019-1555-y
- Description: The quest for novel sources of antibacterial compounds have necessitated the inclusion of ericoid mycorrhizal fungi (ERM) commonly found within the root of ericaceous plants. Agar-well diffusion method was used to detect antibacterial activity and was followed by the microbroth diffusion method [minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)].
- Full Text:
- Date Issued: 2019
Purification and characterization of an amyloglucosidase from an ericoid mycorrhizal fungus (Leohumicola incrustata)
- Adeoyo, Olusegun R, Pletschke, Brett I, Dames, Joanna F
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440405 , vital:73780 , https://doi.org/10.1186/s13568-018-0685-1
- Description: This study aimed to purify and characterize amyloglucosidase (AMG) from Leohumicola incrustata. AMG was purified to homogeneity from cell-free culture filtrate of an ERM fungus grown in a modified Melin–Norkrans liquid medium. The molecular mass of the AMG was estimated to be 101 kDa by combining the results of Sephadex G-100 gel filtration, sodium dodecyl sulphate–polyacrylamide gel electrophoresis, and zymography. The Km and kcat values were 0.38 mg mL−1 and 70 s−1, respectively, using soluble starch as a substrate. The enzyme was stable at 45 °C (pH 5.0), retaining over 65% activity after a pre-incubation period of 24 h. The metal inhibition profile of the AMG showed that Mn2+ and Ca2+ enhanced activity, while it was stable to metals ions, except a few (Al3+, Co2+, Hg2+ and Cd2+) that were inhibitory at a concentration higher than 5 mM. Thin layer chromatography revealed that only glucose was produced as the product of starch hydrolysis. The amylase from L. incrustata is a glucoamylase with promising characteristics such as temperature stability over an extended period, high substrate affinity and stability to a range of chemicals. Also, this study reports for the first time the possibility of using some culturable ERM fungi to produce enzymes for the bio-economy.
- Full Text:
- Date Issued: 2018
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440405 , vital:73780 , https://doi.org/10.1186/s13568-018-0685-1
- Description: This study aimed to purify and characterize amyloglucosidase (AMG) from Leohumicola incrustata. AMG was purified to homogeneity from cell-free culture filtrate of an ERM fungus grown in a modified Melin–Norkrans liquid medium. The molecular mass of the AMG was estimated to be 101 kDa by combining the results of Sephadex G-100 gel filtration, sodium dodecyl sulphate–polyacrylamide gel electrophoresis, and zymography. The Km and kcat values were 0.38 mg mL−1 and 70 s−1, respectively, using soluble starch as a substrate. The enzyme was stable at 45 °C (pH 5.0), retaining over 65% activity after a pre-incubation period of 24 h. The metal inhibition profile of the AMG showed that Mn2+ and Ca2+ enhanced activity, while it was stable to metals ions, except a few (Al3+, Co2+, Hg2+ and Cd2+) that were inhibitory at a concentration higher than 5 mM. Thin layer chromatography revealed that only glucose was produced as the product of starch hydrolysis. The amylase from L. incrustata is a glucoamylase with promising characteristics such as temperature stability over an extended period, high substrate affinity and stability to a range of chemicals. Also, this study reports for the first time the possibility of using some culturable ERM fungi to produce enzymes for the bio-economy.
- Full Text:
- Date Issued: 2018
Improved endoglucanase production and mycelial biomass of some ericoid fungi
- Adeoyo, Olusegun R, Pletschke, Brett I, Dames, Joanna F
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61435 , vital:28026 , https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5209310/
- Description: Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.
- Full Text:
- Date Issued: 2017
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61435 , vital:28026 , https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5209310/
- Description: Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.
- Full Text:
- Date Issued: 2017
Improved endoglucanase production and mycelial biomass of some ericoid fungi
- Adeoyo, Olusegun R, Pletschke, Brett I, Dames, Joanna F
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440352 , vital:73776 , https://doi.org/10.1186/s13568-016-0312-y
- Description: Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.
- Full Text:
- Date Issued: 2017
- Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440352 , vital:73776 , https://doi.org/10.1186/s13568-016-0312-y
- Description: Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.
- Full Text:
- Date Issued: 2017
Undefined cellulase formulations hinder scientific reproducibility
- Himmel, Michael E, Abbas, Charles A, Baker, John O, Bayer, Edward A, Bomble, Yannick J, Brunecky, Roman, Chen, Xiaowen, Felby, Claus, Jeoh, Tina, Kumar, Rajeev, McCleary, Barry V, Pletschke, Brett I, Tucker, Melvin P, Wyman, Charles E, Decker, Stephen R
- Authors: Himmel, Michael E , Abbas, Charles A , Baker, John O , Bayer, Edward A , Bomble, Yannick J , Brunecky, Roman , Chen, Xiaowen , Felby, Claus , Jeoh, Tina , Kumar, Rajeev , McCleary, Barry V , Pletschke, Brett I , Tucker, Melvin P , Wyman, Charles E , Decker, Stephen R
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61402 , vital:28022 , https://doi.org/10.1186/s13068-017-0974-y
- Description: In the shadow of a burgeoning biomass-to-fuels industry, biological conversion of lignocellulose to fermentable sugars in a cost-effective manner is key to the success of second-generation and advanced biofuel production. For the effective comparison of one cellulase preparation to another, cellulase assays are typically carried out with one or more engineered cellulase formulations or natural exoproteomes of known performance serving as positive controls. When these formulations have unknown composition, as is the case with several widely used commercial products, it becomes impossible to compare or reproduce work done today to work done in the future, where, for example, such preparations may not be available. Therefore, being a critical tenet of science publishing, experimental reproducibility is endangered by the continued use of these undisclosed products. We propose the introduction of standard procedures and materials to produce specific and reproducible cellulase formulations. These formulations are to serve as yardsticks to measure improvements and performance of new cellulase formulations.
- Full Text:
- Date Issued: 2017
- Authors: Himmel, Michael E , Abbas, Charles A , Baker, John O , Bayer, Edward A , Bomble, Yannick J , Brunecky, Roman , Chen, Xiaowen , Felby, Claus , Jeoh, Tina , Kumar, Rajeev , McCleary, Barry V , Pletschke, Brett I , Tucker, Melvin P , Wyman, Charles E , Decker, Stephen R
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61402 , vital:28022 , https://doi.org/10.1186/s13068-017-0974-y
- Description: In the shadow of a burgeoning biomass-to-fuels industry, biological conversion of lignocellulose to fermentable sugars in a cost-effective manner is key to the success of second-generation and advanced biofuel production. For the effective comparison of one cellulase preparation to another, cellulase assays are typically carried out with one or more engineered cellulase formulations or natural exoproteomes of known performance serving as positive controls. When these formulations have unknown composition, as is the case with several widely used commercial products, it becomes impossible to compare or reproduce work done today to work done in the future, where, for example, such preparations may not be available. Therefore, being a critical tenet of science publishing, experimental reproducibility is endangered by the continued use of these undisclosed products. We propose the introduction of standard procedures and materials to produce specific and reproducible cellulase formulations. These formulations are to serve as yardsticks to measure improvements and performance of new cellulase formulations.
- Full Text:
- Date Issued: 2017
Hydrolytic enzymes in sewage sludge treatment: a mini-review
- Burgess, Jo E, Pletschke, Brett I
- Authors: Burgess, Jo E , Pletschke, Brett I
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6478 , http://hdl.handle.net/10962/d1006166 , http://hdl.handle.net/10520/EJC116535
- Description: Biological wastewater treatment processes can be classified as either aerobic or anaerobic. These two biological treatment processes are each characterised by groups of micro-organisms and their associated enzymes. Hydrolytic enzymes secreted by these micro-organisms are vital for the rate-limiting step of hydrolysis in the treatment of highly polymeric substrates present in sewage sludge. In this mini-review, the effects of mass transfer limitation, metabolic intermediates, extracellular polymeric substances (EPS), electron acceptor conditions and pH and temperature on the activity of these enzymes are summarised. The most salient and current perspectives of the significance and the role that hydrolytic enzymes play in sewage sludge treatment are highlighted.
- Full Text:
- Date Issued: 2008
- Authors: Burgess, Jo E , Pletschke, Brett I
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6478 , http://hdl.handle.net/10962/d1006166 , http://hdl.handle.net/10520/EJC116535
- Description: Biological wastewater treatment processes can be classified as either aerobic or anaerobic. These two biological treatment processes are each characterised by groups of micro-organisms and their associated enzymes. Hydrolytic enzymes secreted by these micro-organisms are vital for the rate-limiting step of hydrolysis in the treatment of highly polymeric substrates present in sewage sludge. In this mini-review, the effects of mass transfer limitation, metabolic intermediates, extracellular polymeric substances (EPS), electron acceptor conditions and pH and temperature on the activity of these enzymes are summarised. The most salient and current perspectives of the significance and the role that hydrolytic enzymes play in sewage sludge treatment are highlighted.
- Full Text:
- Date Issued: 2008
A novel biosensor for the detection and monitoring of -d-galactosidase of faecal origin in water
- Wutor, V C, Togo, C A, Limson, Janice L, Pletschke, Brett I
- Authors: Wutor, V C , Togo, C A , Limson, Janice L , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6468 , http://hdl.handle.net/10962/d1005797 , http://dx.doi.org/10.1016/j.enzmictec.2006.10.039
- Description: A voltammetric sensor prepared by the immobilization of metallophthalocyanine complexes onto a glassy carbon electrode has been developed for the detection of β-d-galactosidase (B-GAL) of faecal origin in water. Electrooxidation of chlorophenol red, a breakdown product of the chromogenic substrate chlorophenol red β-d-galactopyranoside, was used as a measure of β-d-galactosidase activity. At metallophthalocyanine modified electrodes, in particular copper(II) phthalocyanine, a decrease in electrode fouling was observed. The sensor was sensitive to fluctuations in pH, not significantly affected by temperature variations and could detect one colony forming unit/100 mL in 15 min. Loss of 40% sensitivity was observed over a period of 30 days. A strong correlation between sensor sensitivity and colony forming units was observed. The sensor is capable of detecting viable but nonculturable bacteria, overcoming this drawback of the use of culture media for detection of coliforms.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A , Limson, Janice L , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6468 , http://hdl.handle.net/10962/d1005797 , http://dx.doi.org/10.1016/j.enzmictec.2006.10.039
- Description: A voltammetric sensor prepared by the immobilization of metallophthalocyanine complexes onto a glassy carbon electrode has been developed for the detection of β-d-galactosidase (B-GAL) of faecal origin in water. Electrooxidation of chlorophenol red, a breakdown product of the chromogenic substrate chlorophenol red β-d-galactopyranoside, was used as a measure of β-d-galactosidase activity. At metallophthalocyanine modified electrodes, in particular copper(II) phthalocyanine, a decrease in electrode fouling was observed. The sensor was sensitive to fluctuations in pH, not significantly affected by temperature variations and could detect one colony forming unit/100 mL in 15 min. Loss of 40% sensitivity was observed over a period of 30 days. A strong correlation between sensor sensitivity and colony forming units was observed. The sensor is capable of detecting viable but nonculturable bacteria, overcoming this drawback of the use of culture media for detection of coliforms.
- Full Text:
- Date Issued: 2007
Comparison of the direct enzyme assay method with the membrane filtration technique in the quantification and monitoring of microbial indicator organisms - seasonal variations in the activities of coliforms and E.coli, temperature and pH
- Wutor, V C, Togo, C A, Pletschke, Brett I
- Authors: Wutor, V C , Togo, C A , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6479 , http://hdl.handle.net/10962/d1006241
- Description: The aim of this project was to monitor variations and relationships between coliform and E. coli counts, the activities of their marker enzymes GAL and GUD, and temperature and pH over a period of 12 months in river samples obtained from the Eastern Cape, South Africa. Several polluted water samples were collected for direct coliform β-D-galactosidase (B-GAL) and Escherichia coli β-D-glucuronidase (B-GUD) assays and the membrane filtration technique. While all the samples showed enzyme activities, not all exhibited growth on CM1046 media. Variation in B-GAL activity (40%) was observed between November (highest activity month) and May (lowest activity month). The highest and lowest B-GUD activities were observed in the months of September and May/June, respectively. The sensitivity of the spectrophotometric assay method was indicated by a limit of detection (LOD) of 1 coliform forming unit (CFU)/100 mℓ and 2 CFU/100 mℓ for coliforms and E. coli, respectively. There was a significant (P < 0.05) positive correlation between E. coli counts and GUD activity (R2 = 0.8909). A correlation of R2 = 0.9151 was also observed between total coliforms and B-GAL activity, even though the CFUs were not evenly distributed. Direct enzyme assays were also shown to be more sensitive than the membrane filtration (MF) technique.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6479 , http://hdl.handle.net/10962/d1006241
- Description: The aim of this project was to monitor variations and relationships between coliform and E. coli counts, the activities of their marker enzymes GAL and GUD, and temperature and pH over a period of 12 months in river samples obtained from the Eastern Cape, South Africa. Several polluted water samples were collected for direct coliform β-D-galactosidase (B-GAL) and Escherichia coli β-D-glucuronidase (B-GUD) assays and the membrane filtration technique. While all the samples showed enzyme activities, not all exhibited growth on CM1046 media. Variation in B-GAL activity (40%) was observed between November (highest activity month) and May (lowest activity month). The highest and lowest B-GUD activities were observed in the months of September and May/June, respectively. The sensitivity of the spectrophotometric assay method was indicated by a limit of detection (LOD) of 1 coliform forming unit (CFU)/100 mℓ and 2 CFU/100 mℓ for coliforms and E. coli, respectively. There was a significant (P < 0.05) positive correlation between E. coli counts and GUD activity (R2 = 0.8909). A correlation of R2 = 0.9151 was also observed between total coliforms and B-GAL activity, even though the CFUs were not evenly distributed. Direct enzyme assays were also shown to be more sensitive than the membrane filtration (MF) technique.
- Full Text:
- Date Issued: 2007
ATP-sulphurylase: An enzymatic marker for biological sulphate reduction
- Oyekola, Oluwaseun O, Pletschke, Brett I
- Authors: Oyekola, Oluwaseun O , Pletschke, Brett I
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6461 , http://hdl.handle.net/10962/d1005790 , http://dx.doi.org/10.1016/j.soilbio.2006.05.014
- Description: Adenosine triphosphate-sulphurylase (ATPS) plays a major role in dissimilatory sulphate reduction. In this study, the level of ATPS activity was monitored in a time course study using a biosulphidogenic batch bioreactor system. A coincident decrease in ATPS activity with a decline in sulphate concentration and an increase in sulphide concentration as biosulphidogenesis proceeded was observed. Flask studies further showed sulphate to be stimulatory to ATPS, while sulphide proved to be inhibitory. The effect of ions (Ca^(2+), Cl^(−), Fe^(2+) and Zn^(2+)) on the ATPS activity was also investigated. Most of the ions studied (Ca^(2+), Cl^(−) and Fe^(2+)) were stimulatory at lower concentrations (40–120 mg/l) but proved toxic at higher concentrations (>120 mg/l). In contrast, Zn^(2+) was inhibitory even at low concentrations ( 40 mg/l). ATPS may potentially be used as an enzymatic marker for biological sulphate reduction in sulphate-rich wastewaters and natural environments (anaerobic systems such as soils and sediments found in freshwater and marine systems), providing all residual sulphide and interfering ions are removed using a simple preparative step.
- Full Text:
- Date Issued: 2006
- Authors: Oyekola, Oluwaseun O , Pletschke, Brett I
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6461 , http://hdl.handle.net/10962/d1005790 , http://dx.doi.org/10.1016/j.soilbio.2006.05.014
- Description: Adenosine triphosphate-sulphurylase (ATPS) plays a major role in dissimilatory sulphate reduction. In this study, the level of ATPS activity was monitored in a time course study using a biosulphidogenic batch bioreactor system. A coincident decrease in ATPS activity with a decline in sulphate concentration and an increase in sulphide concentration as biosulphidogenesis proceeded was observed. Flask studies further showed sulphate to be stimulatory to ATPS, while sulphide proved to be inhibitory. The effect of ions (Ca^(2+), Cl^(−), Fe^(2+) and Zn^(2+)) on the ATPS activity was also investigated. Most of the ions studied (Ca^(2+), Cl^(−) and Fe^(2+)) were stimulatory at lower concentrations (40–120 mg/l) but proved toxic at higher concentrations (>120 mg/l). In contrast, Zn^(2+) was inhibitory even at low concentrations ( 40 mg/l). ATPS may potentially be used as an enzymatic marker for biological sulphate reduction in sulphate-rich wastewaters and natural environments (anaerobic systems such as soils and sediments found in freshwater and marine systems), providing all residual sulphide and interfering ions are removed using a simple preparative step.
- Full Text:
- Date Issued: 2006
Cellulases (CMCases) and polyphenol oxidases from thermophilic Bacillus spp
- Mayende, Lungisa, Wilhelmi, Brendan S, Pletschke, Brett I
- Authors: Mayende, Lungisa , Wilhelmi, Brendan S , Pletschke, Brett I
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6462 , http://hdl.handle.net/10962/d1005791 , http://dx.doi.org/10.1016/j.soilbio.2006.03.019
- Description: In composting, organic matter is degraded by cellulases and ligninolytic enzymes at temperatures typically above 50 °C. This study isolated thermophilic microorganisms from a compost system that were then screened for cellulase and polyphenol oxidase activity. Temperature optima for the cellulases and polyphenol oxidases were determined as 70 and 40 °C, respectively. Maximal cellulase activity was determined as 1.333 mg glucose released ml[superscript −1] min[superscript −1]. Maximal polyphenol oxidase activity attained was 5.111 nmol phenol ml[superscript −1] min[superscript −1]. Cellulases were found to be stable over a period of 1 h. The isolated compost microorganisms were identified as strains of Bacillus using 16S ribosomal DNA sequence analysis.
- Full Text:
- Date Issued: 2006
- Authors: Mayende, Lungisa , Wilhelmi, Brendan S , Pletschke, Brett I
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6462 , http://hdl.handle.net/10962/d1005791 , http://dx.doi.org/10.1016/j.soilbio.2006.03.019
- Description: In composting, organic matter is degraded by cellulases and ligninolytic enzymes at temperatures typically above 50 °C. This study isolated thermophilic microorganisms from a compost system that were then screened for cellulase and polyphenol oxidase activity. Temperature optima for the cellulases and polyphenol oxidases were determined as 70 and 40 °C, respectively. Maximal cellulase activity was determined as 1.333 mg glucose released ml[superscript −1] min[superscript −1]. Maximal polyphenol oxidase activity attained was 5.111 nmol phenol ml[superscript −1] min[superscript −1]. Cellulases were found to be stable over a period of 1 h. The isolated compost microorganisms were identified as strains of Bacillus using 16S ribosomal DNA sequence analysis.
- Full Text:
- Date Issued: 2006