Monday, May 4, 2009
5-77
Screening and production study of xylanase producer microorganisms from the Brazilian Cerrado
Hemicelluloses are polysaccharides of low molecular weight including xylan, mannan, galactan arabinan and arabinaxylan. Xylan is the most common hemicellulosic polysaccharide in cell walls of land plants, comprising a backbone of xylose residues linked by β-1,4-glycosidic bonds. Xylanolytic enzymes from microorganism have attracted a great deal of attention in the last decade, because of their biotechnological in various industrial processes, such as food, feed, ethanol and pulp and paper industries. A microbial screening of xylanase producer was carried out in Brazilian Cerrado area from Selviria, Mato Grosso do Sul State , Brazil 10.0 g .L-1 of corn husk, 5.0 g .L-1 of meat extract, 0.20 g .L-1 of peptone and 5.0 g .L-1 of Na2CO3 added separately at 45 ºC. The bacterial named P5B1 was cultivated on submerged fermentation using as substrate xylan, wheat bran, corn husk, corn cob and crushed sugar-cane. Corn husk and crushed sugar-cane show a good xylanase activity after 72 hours of fermentation. Crude xylanase was characterized and the optimum pH was 5.5; and it was stable in the pH range 5.0-10.0. The optimum temperature was 60°C at pH 6.5; and it was thermally stable up to 50 ºC. A fungus named P2D16 was cultivated on solid state fermentation using as substrate source wheat bran, wheat bran plus sawdust, corn husk, corn cob and crushed sugar-cane. Wheat bran and corn cobs show the better xylanase production after 72 and 96 hours of fermentation, respectively.
Supported by FUNDUNESP
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