Isolation and enzyme production of a xylanase-producing strain, Bacillus sp. AMX-4

摘要

A bacterium producing the extracellular xylanase was isolated from soil and has been identified as a Bacillus sp. strain. The isolate, named Bacillus sp. AMX-4, was shown to be similar to B. subtilis strain on the basis of its chemical compositions.The xylanase of culture supernatant was most active at 50 deg C and pH 6.0. The additional carbon sources including monosaccharides, disaccharides, wheat bran, and rice straw increased the enzyme productivity. Especially, the maximum xylanase productivity was reached 29.2 units/ml in LB medium supplemented with 1.5 percent (w/v) xylose, which was 16-folds more than that in LB medium. As the results of investigating the effects of xylose on cell growth and xylanase productivity of Bacillus sp. AMX-4, increase of xylanase production was owing to the induction of xylanase biosynthesis. It was also found that the enzyme production was in association with the growth of Bacillus sp. AMX-4.