Isolation and Characterization of Novel Lignolytic, Cellulolytic, and Hemicellulolytic Bacteria from Wood-Feeding Termite Cryptotermes brevis

ABSTRACT

In a natural ecosystem, various organisms digest and hydrolyze lignocellulose biomass efficiently. Termites are one of them. They digest lignocellulose biomass with the help of symbiotic microorganisms in their gut. Therefore, termites gut may harbor potential sources of microorganisms capable to degrade lignocellulose biomass. In this study, termite gut microbiomes of Cryptotermes brevis species were isolated and identified for their capability to degrade lignin and polysaccharides. Alkali lignin, carboxymethylcellulose, and xylan were used as the only carbon sources in the medium to isolate lignin-, cellulose-, and hemicellulose-degrading bacteria. By this method, two bacteria strains, Bacillus sp. BMP01 and Ochrobactrum oryzae BMP03 strain were isolated and identified. Bacillus sp. BMP01 strain has capabilities to hydrolyze carboxymethylcellulose and xylan to glucose and xylose, respectively. This strain showed high xylanase activity (about 0.21 U/ml) and carboxymethyl cellulase activity (about 0.25 U/ml). The ability to hydrolyze both carboxymethylcellulose and xylan makes it superior to other known cellulolytic bacteria. Ochrobactrum oryzae BMP03 strain showed laccase activity, which indicates its ability to depolymerize lignin. Lignocellulose-degrading bacteria play a vital role in the biological conversion of lignocellulose biomass to biofuel. Overall, this study shows that termite's gut microbiomes are potential sources of lignocellulose-degrading bacteria that can be cultured and used in the biological conversion of lignocellulose biomass to biofuel

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