The litterfall is the major organic material deposited in soil of Brazilian Caatinga biome, thus providing the ideal conditions for plant biomass-degrading microorganisms to thrive. Herein, the phylogenetic composition and lignocellulose-degrading capacity have been explored for the first time from a fosmid library dataset of Caatinga soil by sequence-based screening. A complex bacterial community dominated by Proteobacteria and Actinobacteria was unraveled. SEED subsystems-based annotations revealed a broad range of genes assigned to carbohydrate and aromatic compounds metabolism, indicating microbial ability to utilize plant-derived material. CAZy-based annotation identified 7275 genes encoding 37 glycoside hydrolases (GHs) families related to hydrolysis of cellulose, hemicellulose, oligosaccharides and other lignin-modifying enzymes. Taxonomic affiliation of genes showed high genetic potential of the phylum Acidobacteria for hemicellulose degradation, whereas Actinobacteria members appear to play an important role in celullose hydrolysis. Additionally, comparative analyses revealed greater GHs profile similarity among soils as compared to the digestive tract of animals capable of digesting plant biomass, particularly in the hemicellulases content. Combined results suggest a complex synergistic interaction of community members required for biomass degradation into fermentable sugars. This large repertoire of lignocellulolytic enzymes opens perspectives for mining potential candidates of biochemical catalysts for biofuels production from renewable resources and other environmental applications.
The main aim was to evaluate the occurrence of cellulolytic bacteria from the Stain house Lake, located at Admiralty Bay, Antarctica. Thick cotton string served as a cellulose bait for the isolation of bacteria. A total of 52 bacterial isolates were recovered and tested for their cellulase activity, and two of them, isolates CMAA 1184 and CMAA 1185, showed significant cellulolytic activity on carboxymethylcellulose agar plates. Phylogenetic analysis placed the isolates into the Bacillus 16S ribosomal RNA gene subclade. Both isolates produced a cold-active cellulase which may play a crucial role in this extreme environment.
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