Revisiting cellulase production and redefining current strategies based on major challenges
- Kuhad, Ramesh Chander, Deswal, Deepa, Sharma, Sonia, Bhattacharya, Abhishek, Jain, Kavish Kumar, Kaur, Amandeep, Pletschke, Brett I, Singh, Ajay, Karp, Matti
- Authors: Kuhad, Ramesh Chander , Deswal, Deepa , Sharma, Sonia , Bhattacharya, Abhishek , Jain, Kavish Kumar , Kaur, Amandeep , Pletschke, Brett I , Singh, Ajay , Karp, Matti
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66142 , vital:28909 , https://doi.org/10.1016/j.rser.2015.10.132
- Description: publisher version , Lignocellulosic biomass has been considered as an important and sustainable source of renewable energy. Cellulose constitutes the major component of the lignocellulosic biomass and also offers maximum recalcitrance towards its fullest utilization. The enzymatic breakdown of cellulose is achieved through cellulases. Diverse forms of microbes including fungi, bacteria, actinomycetes and yeast are known to produce cellulases that have found extensive application in various industries. Due to the current global political unrest over oil prices and the threat of global warming following combustion of fossil fuels, the paradigm of research is now focused on biofuel production from plant biomass. Conventional approaches have not been economically feasible for meeting the demands of the industry. This review provides an update regarding the status of present microbial cellulase production technologies and research with special reference to solid state fermentation and different molecular techniques such as mutagenesis, metabolic engineering and heterologous gene expression of cellulases from different microbial domains with improved catalytic and stability properties. Metagenomic and genomic studies for mining of novel cellulase genes in addition to screening of culturable strains using conventional methods have been advanced. In addition the bottlenecks associated with cellulase production and how the future research needs to be directed to provide a comprehensive technology for the production of cellulases with novel traits for application at an industrial level without economic constraints are discussed.
- Full Text: false
- Date Issued: 2016
- Authors: Kuhad, Ramesh Chander , Deswal, Deepa , Sharma, Sonia , Bhattacharya, Abhishek , Jain, Kavish Kumar , Kaur, Amandeep , Pletschke, Brett I , Singh, Ajay , Karp, Matti
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66142 , vital:28909 , https://doi.org/10.1016/j.rser.2015.10.132
- Description: publisher version , Lignocellulosic biomass has been considered as an important and sustainable source of renewable energy. Cellulose constitutes the major component of the lignocellulosic biomass and also offers maximum recalcitrance towards its fullest utilization. The enzymatic breakdown of cellulose is achieved through cellulases. Diverse forms of microbes including fungi, bacteria, actinomycetes and yeast are known to produce cellulases that have found extensive application in various industries. Due to the current global political unrest over oil prices and the threat of global warming following combustion of fossil fuels, the paradigm of research is now focused on biofuel production from plant biomass. Conventional approaches have not been economically feasible for meeting the demands of the industry. This review provides an update regarding the status of present microbial cellulase production technologies and research with special reference to solid state fermentation and different molecular techniques such as mutagenesis, metabolic engineering and heterologous gene expression of cellulases from different microbial domains with improved catalytic and stability properties. Metagenomic and genomic studies for mining of novel cellulase genes in addition to screening of culturable strains using conventional methods have been advanced. In addition the bottlenecks associated with cellulase production and how the future research needs to be directed to provide a comprehensive technology for the production of cellulases with novel traits for application at an industrial level without economic constraints are discussed.
- Full Text: false
- Date Issued: 2016
The inhibitory effects of various substrate pre-treatment by-products and wash liquors on mannanolytic enzymes
- Malgas, Samkelo, Van Dyk, J Susan, Abboo, Sagaran, Pletschke, Brett I
- Authors: Malgas, Samkelo , Van Dyk, J Susan , Abboo, Sagaran , Pletschke, Brett I
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66156 , vital:28911 , https://doi.org/10.1016/j.molcatb.2015.11.014
- Description: publisher version , Biomass pre-treatment is essential for achieving high levels of bioconversion through increased accessibility of hydrolytic enzymes to hydrolysable carbohydrates. However, pre-treatment by-products, such as sugar and lignin degradation products, can negatively affect the performance of hydrolytic (mannanolytic) enzymes. In this study, two monomeric sugars, five sugar degradation products, five lignin derivatives and four liquors from biomass feedstocks pre-treated by different technologies, were evaluated for their inhibitory effects on mannanolytic enzymes (α-galactosidases, β-mannanases and β-mannosidases). Lignin derivatives elicited the greatest inhibitory effect on the mannanolytic enzymes, followed by organic acids and furan derivatives derived from sugar degradation. Lignin derivative inhibition appeared to be as a result of protein–phenolic complexation, leading to protein precipitating out of solution. The functional groups on the phenolic lignin derivatives appeared to be directly related to the ability of the phenolic to interfere with enzyme activity, with the phenolic containing the highest hydroxyl group content exhibiting the greatest inhibition. It was also demonstrated that various pre-treatment technologies render different pre-treatment soluble by-products which interact in various ways with the mannanolytic enzymes. The different types of biomass (i.e. different plant species) were also shown to release different by-products that interacted with the mannanolytic enzymes in a diverse manner even when the biomass was pre-treated using the same technology. Enzyme inhibition by pre-treatment by-products can be alleviated through the removal of these compounds prior to enzymatic hydrolysis to maximize enzyme activity.
- Full Text: false
- Date Issued: 2016
- Authors: Malgas, Samkelo , Van Dyk, J Susan , Abboo, Sagaran , Pletschke, Brett I
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66156 , vital:28911 , https://doi.org/10.1016/j.molcatb.2015.11.014
- Description: publisher version , Biomass pre-treatment is essential for achieving high levels of bioconversion through increased accessibility of hydrolytic enzymes to hydrolysable carbohydrates. However, pre-treatment by-products, such as sugar and lignin degradation products, can negatively affect the performance of hydrolytic (mannanolytic) enzymes. In this study, two monomeric sugars, five sugar degradation products, five lignin derivatives and four liquors from biomass feedstocks pre-treated by different technologies, were evaluated for their inhibitory effects on mannanolytic enzymes (α-galactosidases, β-mannanases and β-mannosidases). Lignin derivatives elicited the greatest inhibitory effect on the mannanolytic enzymes, followed by organic acids and furan derivatives derived from sugar degradation. Lignin derivative inhibition appeared to be as a result of protein–phenolic complexation, leading to protein precipitating out of solution. The functional groups on the phenolic lignin derivatives appeared to be directly related to the ability of the phenolic to interfere with enzyme activity, with the phenolic containing the highest hydroxyl group content exhibiting the greatest inhibition. It was also demonstrated that various pre-treatment technologies render different pre-treatment soluble by-products which interact in various ways with the mannanolytic enzymes. The different types of biomass (i.e. different plant species) were also shown to release different by-products that interacted with the mannanolytic enzymes in a diverse manner even when the biomass was pre-treated using the same technology. Enzyme inhibition by pre-treatment by-products can be alleviated through the removal of these compounds prior to enzymatic hydrolysis to maximize enzyme activity.
- Full Text: false
- Date Issued: 2016
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