Induction of alpha-galactosidase in Penicillium ochrochloron by guar (Cyamopsis tetragonobola) gum.

High yields of extracellular alpha-galactosidase from fungal cultures were obtained by inducing enzyme production with guar gum (a galactomannan obtained from the seeds of Cyamopsis tetragonobola) as the sole carbon source. An alpha-galactosidase was isolated from the culture medium of Penicillium ochrochloron culture and purified 867-fold by CM-cellulose and Sephacryl S-200 column chromatography to apparent homogeneity. Gel-filtration data revealed an M(r) of 57,500, which was in close agreement with SDS/PAGE M(r) estimation, for a single band, of 60,200. The alpha-galactosidase activity is strictly dependent upon the pH and temperature of the incubation medium, being maximal at pH 4.5 and 55 degrees C respectively. This enzyme from P. ochrochloron was isolated and purified, devoid of beta-mannanase activity, which cleaves the main beta-mannan backbone of galactomannans and greatly diminishes its gel-promoting capacity. The properties of purified guar-gum-induced alpha-galactosidase activity in P. ochrochloron culture were evaluated in order to ascribe a possible application for alpha-galactosidase in the controlled generation of an improved guar-gum-based gel promoter.