Hemicellulases ofBacillusspecies: preliminary comparative studies on production and properties of mannanases and galactanases

摘要

A range of Bacillus subtilis strains and otherBacillusspecies were screened for mannanase, β‐mannosidase and galactanase activities. Maximum mannanase activity, 106.2 units/ml, was produced byB. subtilisNRRL 356. β‐Mannosidase and galactanase activities from all strains were relatively low. The effect of carbon and nitrogen source on mannanase and galactanase production byB. brevisATCC 8186,B. licheniformisATCC 27811,B. polymyxaNRRL 842 andB. subtilisNRRL 356 was investigated. Highest mannanase production was observed in the four strains tested when the mannan substrate, locust bean gum, was used as carbon source. Induction was most dramatic in the case ofB. subtilisNRRL 356 where only basal enzyme levels were produced in the presence of other carbon sources. β‐Mannosidase was induced in the fourBacilluscultures by locust bean gum. Results indicated that galactose acted as an inducer for production of galactanase. Organic and inorganic nitrogen sources resulted in induction of high mannanase titres inB. subtilis.Highest galactanase activity was produced by each organism in media containing sodium nitrate as nitrogen source. Mannanases fromB. brevis, B. licheniformis, B. polymyxaandB. subtilisretained 100 residual activity after a 3 h incubation at 65°C, 65°C, 60°C and 55°C respectively. Galactanases retained more than 95 activity at 55°C after 3 h. The pH optima of mannanases ranged from 6.5–6.8 whereas galactanases ranged from 5.1 in the case ofB. brevisto 7.0