Isolation of cellulose degrading microorganisms from biogas slurry and their application in rice straw degradation
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Date
2021-10
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Rice is one of the major food grain crops in the world. Besides grain, it also produces large amount of waste in the form of rice straw. Present study explores the biogas slurry microorganisms in the biodegradation of rice straw. Efforts were also made to identify potential cellulase producing microbial cultures from biogas slurry that play an important role in the hydrolysis of lignocellulosic biomass. 45 bacterial and fungal cultures were isolated from biogas slurry. These isolates were screened for cellulase and xylanase enzyme activities both qualitatively and quantitatively. The potential fungal isolate SSF4 exhibiting maximum FPase (0.315 U/mL) activity on CMC minimal salt medium, fungal isolate SSF1 showing highest β-glucosidase (0.552 U/mL) activity on CMC minimal salt medium and SSF1 showed maximum xylanase (0.510 U/mL) activity on wheat bran minimal salt medium were selected for biodegradation of rice straw. Based on the morphological characterization and microscopic observation of selected strain revealed that SSF1 culture was identified as Aspergillus genus and SSF4 culture as Trichderma genus. The consortium of these two strains with biogas slurry was effective in biodegradation of rice straw. The rice straw was first subjected to alkaline pretreatment for removal of lignin content from rice straw. For biological treatment, the alkaline pretreated rice straw was treated with selected fungal isolates and biogas slurry. The pretreated and biologically treated rice straw was monitored through FTIR analysis to reveal the chemical changes in the lignocellulosic biomass of rice straw. The future research should be focus on the study this consortium at the biochemical level and optimization would be needed for higher production of enzyme to improve biodegradation of rice straw.