https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:3910 Wed 21 Jul 2021 13:46:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3947 Wed 12 May 2021 23:14:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3972 Wed 12 May 2021 22:58:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3895 Wed 12 May 2021 22:51:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4071 Wed 12 May 2021 22:26:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4009 50%). Thus, it can be concluded that the cavities of apoferitin and GroEL acted as nanobiofactories for the synthesis and confinement of the size and shape of nanoparticles. Furthermore, the interior of these proteins provided a shielding effect for these nanoparticles and thus reduced/prevented their possible neurotoxic effect and confirmed safety in their method of production and application. The findings from this study would prove beneficial in the application of these nanoparticles as a potential drug/drug delivery vehicle for the prevention, treatment/management of diseases associated with these enzymes/proteins.]]> Wed 12 May 2021 22:22:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3964 0.05]. These results imply that differences in the biosynthetic pathways for biomass accumulation in sibling strains play a significant role in the intraspecific variation observed in pollutant sensitivity, pollutant degradation, and enzyme production. Categorical analysis of intraspecific differences was assessed according to four criterions. These included growth, extracellular peroxidase activities, tolerance to toxic pollutants and the biodegradation of model pollutants. Sibling strains showing the most variable responses in three or more of the selective criterion were recommended for further studies. These strains include P. chrysosporium ME446, BS 2.52, BS 13, BS 17, BS 18, and BS 24. Interestingly, BS 2.52 (a dikaryotic strain generating from the crossing of two haploid progeny) showed significantly lower degradation capabilities than the wildtype parent strain ME446. The inherited variability observed between sibling strains is to be further explored through proteome and transcriptome analysis and genetic linkage studies aimed at describing the mechanisms or pathways conferring tolerance to or degradation of environmental pollutants. In examining fewer organisms at this next level, the number of replicates examined can be increased and thus the power of detection of experimental procedures improved, enabling the detection of multigenic traits amongst genetically related organisms. Growth was shown to play a significant role in the intraspecific differences detected in pollutant sensitivity and degradation between sibling strains. Little is known about the mechanism of growth and differentiation, or the role of differentiation in regulating the lignolytic activity in this organism. The membrane gradostat bioreactor and a unique plug-flow membrane bioreactor were evaluated as novel tools with which to further explore the relationship between secondary metabolism, pollutant degradation and biofilm development in sibling strains. High yield MnP production at levels as high as 1478.8 U.l-1 was achieved using a laboratory scale membrane gradostat bioreactor. Furthermore, extensive mycelial differentiation and tissue formation are reported for P. chrysosporium in both the membrane gradostat bioreactor and plug-flow membrane bioreactor. Intraspecific differences in the extent of this differentiation were observed in strains ME446, BS 13, BS 17 and BS 26 cultured using the membrane gradostat bioreactor, highlighting the potential of these techniques as a platform for future strain improvement strategies.]]> Wed 12 May 2021 22:17:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20972 Wed 12 May 2021 20:55:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3951 Wed 12 May 2021 20:17:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3907 Wed 12 May 2021 20:12:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4035 Wed 12 May 2021 19:50:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4011 98 % in 24 – 30 h batch cycles. Comparable performance between the packing materials was shown. Uptake by the packing was negligible and stripping of compounds induced by aeration had a minimal effect on biodegradation efficiency. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to sustain fungal activity in inert vs. organic material packed systems. It was shown that a co-culture consisting of sulphate-reducing and dechlororespiring bacteria established in fed-batch and soil flasks, as well as pine chip-packed fluidized bed reactors. Results showed reductive dechlorination of 2,4,6-TCP to be in strict dependence on the activity of the sulphate-reducing population, sulphate and lactate concentrations. Transformation to 2,4-DCP, 4-CP and phenol was enhanced in sulphate deficient conditions. Dechlororespiring activity was found to be dependent on the fermentative activity of sulphate-reducing bacteria, and the culture was also shown to mobilize and dechlorinate TCP in soils contaminated with the pollutant. Linking the systems achieved degradation of the compound by > 99 % through fungal mineralization of metabolites produced in the dechlororespiring stage of the system. pH correction to the anaerobic reactor was found to be necessary since acidic effluent from the fungal reactor inhibited sulphate reduction and dechlorination. The fungal reactor system was evaluated at intermediate-scale using a complex waste oil recycling effluent. Substantial COD reduction (> 96 % in 48 h batch cycles) and removal of specific effluent hydrocarbon components was shown in diluted, undiluted (COD > 37 g.L⁻¹) and 2,4,6-TCP-spiked effluents. Industrial application of the fungal reactor was evaluated in a 14 m³ pilot plant operated on-site at a waste oil processing plant.]]> Wed 12 May 2021 19:45:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3992 Wed 12 May 2021 19:32:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4007 Wed 12 May 2021 19:29:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4037 Wed 12 May 2021 19:17:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3933 Wed 12 May 2021 19:16:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3920 Wed 12 May 2021 19:11:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4103 Wed 12 May 2021 18:47:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3976 Wed 12 May 2021 18:46:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4091 Wed 12 May 2021 18:45:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4017 Wed 12 May 2021 18:40:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4132 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.]]> Wed 12 May 2021 18:32:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3943 Wed 12 May 2021 18:23:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4101 Wed 12 May 2021 18:21:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4001 Wed 12 May 2021 18:20:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3977 Wed 12 May 2021 18:16:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4076 10,000 mg/I), numerous metals and high concentrations of those metals (> 20 mg/l of platinum group metals) in the wastewater are the main challenges for biological removal of nitrogenous compounds from PMR wastewater. Nitrogenous compounds such as NH₄⁺-N and N0₃-N are strong metal ligands, which make it difficult to recover metals from the wastewater. Therefore, a bioprocess was developed for removal of nitrogenous compounds from carefully simulated PMR wastewater. A preliminary investigation of metal wastewater was carried out to determine its composition and physico-chemical properties, the ability to nitrify and denitrify under different pH conditions and denitrification with different carbon Source compounds and amounts. Even at pH 4, nitrification could be carried out. A suitable hydraulic retention time was found to be 72 hours. There was no significant difference between sodium acetate and sodium lactate as carbon sources for denitrification. Based on these results, a reactor comparison study was carried out using simulated PMR wastewater in three types of reactors: continuously stirred tank reactor (CSTR), packed-bed reactor (PBR) and airlift suspension reactor (ALSR). These reactors were fed with 30 mg/l of Rh bound in an NH₄⁺ based compound (Claus salt: pentaaminechlororhodium (III) dichloride). Total nitrogen removal efficiencies of > 68 % , > 79 % and > 45 % were obtained in the CSTR, PBR and ALSR, respectively. Serially connected CSTR-PBR and PBR-CSTR reactor configurations were then studied to determine the best configuration for maximum removal of nitrogenous compounds from the wastewater. The PBR-CSTR configuration gave consistent biomass retention and automatic pH control in the CSTR. Ammonium removal efficiencies > 95 % were achieved in both reactors. As poor nitrate removal was observed a toxicity study was carried out using respirometry and the half saturation inhibition coefficients for Pt, Pd, Rh and Ru were found to be 15.81, 25.00, 33.34 and 39.25 mg/l, respectively. A mathematical model was developed to describe the nitrogen removal in PMR wastewater using activated sludge model number 1 (ASMl), two step nitrification and metal toxicity. An operational protocol was developed based on the literature review, experimental work and simulation results. The optimum reactor configuration under the set conditions (20 mg/I of Rh and < 100 mg/I of NH₄⁺-N) was found to be PBR-CSTR-PBR process, which achieved overall NH₄⁺-N and N0₃⁻-N removal efficiencies of > 90 % and 95 %, respectively. Finally, a rudimentary microbial characterisation was carried out on subsamples from the CSTR and PBRsecondary. It was found that the CSTR biomass consisted of both rods and cocci while PBRsecondary consisted of rods only. Based on these experimental works, further research needs and recommendations were made for optimisation of the developed bioprocess for removal of nitrogenous compounds from PMR wastewater.]]> Wed 12 May 2021 18:01:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3991 Wed 12 May 2021 17:52:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3905 Wed 12 May 2021 17:51:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4143 Wed 12 May 2021 17:50:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3888 Wed 12 May 2021 17:29:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3932 Wed 12 May 2021 17:27:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4063 Wed 12 May 2021 17:18:28 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3970 Wed 12 May 2021 17:15:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3899 Wed 12 May 2021 17:09:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3963 Wed 12 May 2021 16:45:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3924 Wed 12 May 2021 16:20:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3926 Wed 12 May 2021 16:16:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4036 Wed 12 May 2021 16:13:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3894 Wed 12 May 2021 16:06:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4034 Wed 12 May 2021 16:06:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3906 Wed 12 May 2021 16:01:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3935 Wed 12 May 2021 15:49:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4126 Wed 12 May 2021 15:44:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4032 Wed 05 Apr 2023 07:00:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3949 Thu 13 May 2021 13:31:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4105 Thu 13 May 2021 10:52:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3939 Thu 13 May 2021 08:52:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3984 Thu 13 May 2021 07:32:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3929 Thu 13 May 2021 07:14:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4049 Thu 13 May 2021 07:11:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3983 Thu 13 May 2021 07:02:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4046 Thu 13 May 2021 06:51:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4073 Thu 13 May 2021 06:37:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4062 Thu 13 May 2021 06:26:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3938 Thu 13 May 2021 06:15:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3944 Thu 13 May 2021 06:01:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4061 Thu 13 May 2021 05:54:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3958 Thu 13 May 2021 05:51:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4089 Thu 13 May 2021 05:24:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4094 Thu 13 May 2021 05:21:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4060 Thu 13 May 2021 05:15:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3917 Thu 13 May 2021 05:04:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3928 Thu 13 May 2021 05:03:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3952 Thu 13 May 2021 04:58:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3969 Thu 13 May 2021 04:40:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4041 Thu 13 May 2021 04:32:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4079 Thu 13 May 2021 04:31:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3942 Thu 13 May 2021 04:30:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4051 Thu 13 May 2021 04:29:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4016 Thu 13 May 2021 03:57:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3971 Thu 13 May 2021 03:41:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3996 Thu 13 May 2021 03:32:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3916 Thu 13 May 2021 03:16:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3997 Thu 13 May 2021 03:09:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4108 Thu 13 May 2021 03:02:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4015 chitin> glucan > intact cell walls exists. However, these components differ in their affinities for metal ions. Storage of metal ions within the cell occurs predominantly in the vacuole. The present study concluded that metal accumulation by the vacuole could be related to size. Metal accumulation occurred in the order of Cu2+ > Co2+ > Cd2+ with a corresponding decrease in atomic radii of Cd2+ > C02+ > Cu2+. Vacuolar ion deposition occurs at an early stage during the internalization of metal ions within the yeast cells. At the onset of vacuolar saturation, depositions of metal ions as granules within the cytosol occurs. In the presence of heavy metal cations viable yeast cells can be shown to exhibit two types of cellular responses. Uptake of Cu2+ and Cd2+ causes the loss of intracellular physiological cations from within the yeast cell. In comparison, uptake of Co2+ into the cell does not have this effect. All three heavy metal cations initiate plasma cell membrane permeability, thus the Cu2+ and Cd2+ induced loss of the intracellular cations, occurs. ~ a result of ion-exchange mechanisms and not due to cation leakage brought about by membrane permeabilization. Uptake of heavy metals by viable yeasts appears to be generally non-selective though the amount of metals accumulated are largely affected by the ratio of ambient metal concentration to biomass quantity. In addition, the energy dependent nature of internalization necessitates the availability of an external energy source for metal uptake by viable yeast cells. For these reasons metal removal from industrial waste water was investigated using non-viable biomass. By immobilizing the yeast cells additional mechanical integrity and stability was conferred apon the biomass. The three types of biomass preparations developed in this study, viz. polyvinyl alcohol (PV A) Na-alginate, PV A Na-orthophosphate and alkali treated polyethylenimine (PEI):glutaraldehyde (GA) biomass pellets, all fulfilled the necessary physical requirements. However, the superior metal accumulating properties of the PEI:GA biomass determined its selection as a biosorbent for bioremediation purposes. Biosorption of heavy metals by PEI:GA biomass is of a competitive nature, with the amount of metal accumulated influenced by the availability of the metal ions. This availability is largely determined by the solution pH. At low pH values the affinity of the biomass for metals decreases, whilst enhanced metal biosorption occurs at higher pHs, ego pH 4.5 - 6.0. PEI:GA biomass pellets can be implemented -as a biosorbent for the bi9remediaiton of high concentration, low-volume metal containing industrial waste. Several options regarding the bioremediation system are available. Depending on the concentration of the metals in the effluent, the bioremediation process can either be used independently or as part of a biphasic remediation system for the treatment of waste water. Initial phase chemical modification may be required, whilst two types of biological systems can be implemented as 'part of the second phase. The PEI:GA biomass can either be contained within continuous-flow fixed bed tanks or continuous-flow stirred bioreactor tanks. Due to the simplicity of the process and the ease with which scale-up is facilitated, the second type of system shows greater application potential for the treatment of this type of industrial waste water than the fixed-bed systems.]]> Thu 13 May 2021 02:58:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4117 Thu 13 May 2021 02:12:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3967 Thu 13 May 2021 02:10:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3979 Thu 13 May 2021 02:00:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4109 Thu 13 May 2021 01:52:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:31426 Thu 13 May 2021 01:45:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3930 Thu 13 May 2021 01:44:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4047 Thu 13 May 2021 01:29:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3934 Thu 13 May 2021 01:28:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3937 Thu 13 May 2021 01:19:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3900 Thu 13 May 2021 01:07:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4006 Thu 13 May 2021 01:04:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3887 Thu 13 May 2021 00:48:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4114 Thu 13 May 2021 00:22:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3936 Thu 13 May 2021 00:16:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4028 Fri 06 Aug 2021 10:23:20 SAST ]]>