Publication: Comparative analysis of sugarcane bagasse metagenome reveals unique and conserved biomass-degrading enzymes among lignocellulolytic microbial communities
Issued Date
2015
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eng
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Mahidol University
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BioMed Central
Bibliographic Citation
Biotechnology for Biofuels. Vol. 8, (2015), 16
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Wuttichai Mhuantong, Varodom Charoensawan, Pattanop Kanokratana, Sithichoke Tangphatsornruang, Verawat Champreda Comparative analysis of sugarcane bagasse metagenome reveals unique and conserved biomass-degrading enzymes among lignocellulolytic microbial communities. Biotechnology for Biofuels. Vol. 8, (2015), 16. doi:Biotechnology for Biofuels Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/2738
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Comparative analysis of sugarcane bagasse metagenome reveals unique and conserved biomass-degrading enzymes among lignocellulolytic microbial communities
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Abstract
Background: As one of the most abundant agricultural wastes, sugarcane bagasse is largely under-exploited, but it
possesses a great potential for the biofuel, fermentation, and cellulosic biorefinery industries. It also provides a
unique ecological niche, as the microbes in this lignocellulose-rich environment thrive in relatively high temperatures
(50°C) with varying microenvironments of aerobic surface to anoxic interior. The microbial community in bagasse thus
presents a good resource for the discovery and characterization of new biomass-degrading enzymes; however, it
remains largely unexplored.
Results: We have constructed a fosmid library of sugarcane bagasse and obtained the largest bagasse metagenome to
date. A taxonomic classification of the bagasse metagenome reviews the predominance of Proteobacteria, which are
also found in high abundance in other aerobic environments. Based on the functional characterization of biomassdegrading
enzymes, we have demonstrated that the bagasse microbial community benefits from a large repertoire of
lignocellulolytic enzymes, which allows them to digest different components of lignocelluoses into single molecule
sugars. Comparative genomic analyses with other lignocellulolytic and non-lignocellulolytic metagenomes show that
microbial communities are taxonomically separable by their aerobic “open” or anoxic “closed” environments.
Importantly, a functional analysis of lignocellulose-active genes (based on the CAZy classifications) reveals core
enzymes highly conserved within the lignocellulolytic group, regardless of their taxonomic compositions. Cellulases, in
particular, are markedly more pronounced compared to the non-lignocellulolytic group. In addition to the core
enzymes, the bagasse fosmid library also contains some uniquely enriched glycoside hydrolases, as well as a large
repertoire of the newly defined auxiliary activity proteins.
Conclusions: Our study demonstrates a conservation and diversification of carbohydrate-active genes among
diverse microbial species in different biomass-degrading niches, and signifies the importance of taking a global
approach to functionally investigate a microbial community as a whole, as compared to focusing on individual
organisms.