Cohnella sp. AR92, xylanolytic bacteria from sugar-cane bagasse

DAVILA, M. JORGELINA; MASINO, LUIS MARIA; PEROTTI, NORA INÉS; ABATE, CARLOS M; MARTINEZ, M. ALEJANDRA

Congreso; 46 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2010

SAIB

Over 300 bacteria were isolated from samples of sugar-cane bagasse and the liquor that flows through the bagasse pile during its pre-treatment for paper production. From them, the xylanolitic bacteria Cohnella sp. AR92 was able to degrade xylan as a major extracellular enzimatic activity. The isolate is a Gram-positive spore-forming bacteria, and was taxonomically characterized by 16S rDNA sequence, ITS-PCR fingerprinting and morphological and biochemical analyses. These led us to conclude that AR92 isolate should be further described as a new species. Protein composition of the crude enzyme preparation was analyzed by SDS-PAGE and zymogram, which showed xylanase activity bands within the range of 440 to 30 kDa. Enzymatic binding of the crude enzyme preparation of Cohnella sp. AR92 to insoluble birchwood and sugar-cane bagasse xylans  was tested and results indicate that Cohnella AR92 has major affinity to sugar-cane bagasse xylan: the crude extract was found to bind to both insoluble substrates at 40% to 50% and 65%, respectively. The adsorption of enzymes to insoluble substrate plays an important role in the efficiency of the enzymatic hydrolysis of the substrates, which could be the reason of higher enzymatic activities observed towards sugar-cane baggasse xylan, as well as an indication of an adaptation to its natural environment.