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Development of Mutants of Melanocarpus albomyces for Hyperproduction of Xylanase
Ranjita Biswas,Vikram Sahai,Saroj Mishra,Virendra Swarup Bisaria 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.5
The wild type filamentous fungus, Melanocarpus albomyces, produces many commercially valuable enzymes, including Xylanases and Xylan-debranching enzymes with low activity. In this paper, we report for the first time the development of M. albomyces mutants from vegetative spores. Profuse sporulation of M. albomyces was induced on Potato Carrot Agar medium. These spores,when subjected to chemical mutation, led to the isolation of the hyper-xylanase producing mutant, viz, M. albomyces IITD3A. Various parameters including number of spores,nitrogen source and C/N ratio of the medium were optimized for production of xylanase by the mutant in a shake flask culture. Under controlled pH at 7.8, the mutant produced highly active xylanase with 415 IU/mL after 36h of growth on soluble alkaline lignocellulosic extract in a 14-L fermentor. The overall productivity of xylanase was 8-fold higher than the wild type culture with11,530 IU/L/h. The enzyme can be easily stored at 37oC for 50 days by addition of a small amount of the preservative - thiomersal. Also, for long term storage, a lyophilized powder form of the enzyme can be used which retained 100% of its activity for > 50 days. When assayed at pH 7.5 and temperature 55oC, the xylanase retained 100% of its original activity,and also at pH 9.0, it retained > 50% of its activity for 2 h,which is promising for its application in the pulp and paper industry.
Sethi Benu,Jain Monika,Chowdhary Manish,Soni Yogesh,Bhatia Yukti,Sahai Vikram,Mishra Saroj The Korean Society for Biotechnology and Bioengine 2002 Biotechnology and Bioprocess Engineering Vol.7 No.1
The cloning and expression of $\beta-glucosidase$ II, encoded by the gene ${\beta}glu2$, from thermotolerant yeast Pichia etchellsii into Escherichia coli is described. Cloning of the 7.3 kb BamHI/SalI yeast insert containing ${\beta}glu2$ in pUC18, which allowed for reverse orientation of the insert, resulted in better enzyme expression. Transformation of this plasmid into E. coli JM109 resulted in accumulation of the enzyme in periplasmic space. At $50^{\circ}C$, the highest hydrolytic activity of 1686 IU/g protein was obtained on sophorose. Batch and fed-batch techniques were employed for enzyme production in a 14 L bioreactor. Exponential feeding rates were determined from mass balance equations and these were employed to control specific growth rate and in turn maximize cell growth and enzyme production. Media optimization coupled with this strategy resulted in increased enzyme units of 1.2 kU/L at a stabilized growth rate of $0.14\;h^{-l}$. Increased enzyme production in bioreactor was accompanied by formation of inclusion bodies.
Saroj Mishra,Benu Sethi,Monika Jain,Manish Chowdhary,Yogesh Soni,Yukti Bhatia,Vikram Sahai 한국생물공학회 2002 Biotechnology and Bioprocess Engineering Vol.7 No.1
The cloning and expression of β-glucosidase II, encoded by the gene bglu2, from thermo- tolerant yeast Pichia etchellsii into Escherichia coli is described. Cloning of the 7.3 kb BamHI/SalI yeast insert containing bglu2 in pUC18, which allowed for reverse orientation of the insert, resulted in better enzyme expression. Transformation of this plasmid into E. coli JM109 resulted in accumulation of the enzyme in periplasmic space. At 50oC, the highest hydrolytic activity of 1686 IU/g protein was obtained on sophorose. Batch and fed-batch techniques were employed for enzyme production in a 14 L bioreactor. Exponential feeding rates were determined from mass balance equations and these were employed to control specific growth rate and in turn maximize cell growth and enzyme production. Media optimization coupled with this strategy resulted in increased enzyme units of 1.2 kU/L at a stabilized growth rate of 0.14 h-1. Increased enzyme production in bioreactor was accompanied by formation of inclusion bodies.