Two types of xylanases of alkalophilic Bacillus sp. No. C-125

One alkalophilic Bacillus sp. strain C-125 (FERM No. 7344) was isolated from soil. From this organism, two types of xylanases, designated xylanase A and xylanase N, were purified by an ammonium sulfate precipitation followed by Biogel P-30 gel filtration, DEAE-cellulose chromatography, and Sephadex G-75 gel filtration. The molecular weights of xylanase A and N were estimated as 43 000 and 16 000, respectively. Immunological experiments indicated that xylanase A and xylanase N were entirely different protein molecules. Xylanase N was most active at pH 6.0–7.0, but xylanase A had a very broad pH activity curve (pH 6–10) and was still active even at pH 12.0. The maximum hydrolysis of xylan by the enzymes was about 25%. Both enzymes split xylan and yielded xylobiose and higher oligosaccharides but could hydrolyze neither xylobiose nor xylotriose. Trans xylosidation activities were detected in both enzymes.