Optimization of thermo-alkalotolerant cellulase enzyme production from Aspergillus terreus PPCF for conversion of delignified bamboo wood biomass into fermentable sugars
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Date
2019-01
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Renewable biofuels are currently considered as more sustainable, cost effective and eco-friendly alternative to fossil fuels. Present study explores the possibility of utilizing bamboo biomass as sustainable feedstock for alcohol industry. Efforts were also made to identify potential cellulase producing native microbial cultures that play an important role in the hydrolysis of lignocellulosic biomass. Seventy two bacterial and fungal cultures were isolated from diverse sources, screened for cellulase enzyme activities both qualitatively and quantitatively and potential fungal isolate PPCF exhibiting maximum β-glucosidase (0.517UmL-1) and FPase (0.166 UmL-1) activity was selected for the bioconversion process. The cellulase enzyme production from PPCF was optimized using OVAT and statistical approach which enhanced the FPase activity to 10.78 U mL-1 and β-glucosidase to 6.62 U mL-1 . The dry powdery biomass of Bambusa balcooa was first subjected to chemical and biological
pre-treatment to remove the lignin content for enhancing saccharification efficiency. The chemical pretreatment followed by biological treatment with lignin degrading fungus (Lenzites elegans WDP2) was optimized and alkaline-oxidative pre-treatment followed by treatment with Lenzites elegans decreased the lignin content from 28% to 8%. The pre-treated substrate was than hydrolysed into fermentable sugars by utilizing cellulase enzyme from the fungal isolate PPCF. Further statistical optimization of bamboo biomass was done of delignified biomass.
Maximum saccharification (56.32%) was observed with enzyme loading of 20.09 FPU g-1 of substrate at 55oC in 24 h. Liquid chromatography mass spectrometry of saccharified fluid of the treated samples revealed the presence of glucose along with other compounds. The
pretreated saccharified biomass was monitored through FTIR and SEM analysis to reveal the chemical changes and occurrence of porosity in the biomass. Based on phenotypic and 5.8 S ITS rRNA gene sequencing, the isolate PPCF was identified as Aspergillus terreus PPCF.
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