THERMOSTABLE ALKALINE CELLULASE FROM AN ALKALIPHILIC ISOLATE, BACILLUS SP. KSM-S237

Thermostable alkaline cellulase (endo-1,4-beta-glucanase, EC 3.2.1.4) activity was detected in the culture medium of a strictly alkaliphilic strain of Bacillus, designated KSM-S237. This novel enzyme was purifi ed to homogeneity by a two-step column-chromatographic procedure with high yield. The N-terminal amino acid sequence of the purified enzyme was n-Phe-Lys-His-Leu-Leu-Gly-Asn-Asp-Asn-Val-Lys-Arg. The enzyme had a molecular mass of approximately 86 kDa and an isoelectric point of p H 3.8. The enzyme had a pH optimum of 8.6-9.0 and displayed maximum ac tivity at 45 degrees C. The alkaline enzyme was stable up to 50 degree s C and more than 30% of the original activity was detectable after he ating at 100 degrees C and at pH 9.0 for 10 min. The enzyme hydrolyzed carboxymethylcellulose, lichenan (beta-1,3;1,4-linkage), and p-nitrop henyl derivatives of cellotriose and cellotetraose. Crystalline forms of cellulose (Avicel and filter paper), H3PO4-swollen cellulose, NaOH- swollen cellulose, curdlan (beta-1,3-linkage), laminarin (beta-1,3;1,6 -linkage), and xylan were barely hydrolyzed at all.