INDUCTION OF XYLANASE IN BACILLUS-CIRCULANS-B(6)

Bacillus circulans B-6 produced extracellular xylanase and beta-xylosidase when grown in a medium containing xylan. To obtain a more effective growth substrate that enhanced xylanase production, a variety of sugars were tested for their inducing abilities. It was found that D-xylose and xylobiose had an inductive effect on xylanase induction at low concentrations. With other sugars tested including D-arabinose, the basal synthesis of xylanase was produced, although D-arabinose was not utilized by the cell as a sole source of carbon. When xylan supplemented with D-xylose was used as the growth substrate, the xylanase activity in the culture filtrate decreased. However, growth on xylan media supplemented with D-galactose or D-arabinose enhanced the production of xylanase in the culture filtrate. The highest level of xylanase was detected when 10 mg/ml xylan was supplemented with 5 Mg/ml D-arabinose resulting in a specific xylanase activity of 8.1 IU/mg protein when 10 mg/ml xylan alone resulted in a specific xylanase activity of 4.1 IU/mg protein.