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Optimization of enzymatic saccharification and fermentation process parameters for production of bioethanol from Populus nigra using recombinant enzymes from Clostridium thermocellum

Author Affiliations

  • 1 Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati- 781 039, Assam, INDIA

Res. J. Recent Sci., Volume 4, Issue (IYSC-2015), Pages 144-156, September,2 (2015)


The optimization of various parameters such as dosage volume of recombinant hydrolytic enzymes from Clostridium thermocellum, inoculum volume of Candida shehatae, pH and temperature was carried out for improved bioethanol production in simultaneous saccharification and fermentation (SSF) process using Taguchi Orthogonal Array design. The initial SSF trials were performed in 100 ml medium at shake flask level using 1% (w/v) ammonia fibre expansion (AFEX) pretreated Populus nigra leafy biomass. The optimized parameters for SSF process were, 2.0 ml recombinant xylanase (CtXyn30A), 2.0 ml recombinant Acetylxylan esterase (Axe2, 4.4 U/mg, 0.37 mg/ml), 4.6 U/mg, 0.31 mg/ml), 2.0 ml C. shehatae (~4.3 x 10 cells/ml), pH 6.5 and temperature 33°C. On the basis of p-value (p 0.05), the three most significant factors were, the inoculum (C. shehatae) volume, temperature and pH. The optimized SSF conditions with 1% (w/v) pretreated biomass at flask level gave an ethanol titre of 1.06 g/l. The monosaccharide analysis of SSF exhibited the release of xylose from hydrolysed biomass. The increased biomass 5% (w/v), under optimized parameters gave an ethanol titre and yield of 6.10 g/l, 0.317 (g of ethanol/g of pretreated biomass) at flask level and its scale-up to 3l bioreactor level contributed ethanol titre of 7.10 g/l and yield 0.369 (g/g), respectively.


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