Enzymatic Hydrolysis of Yeast Cell Walls I. Isolation of Wall-Decomposing Organisms and Separation and Purification of Lytic Enzymes

Abstract

Tanaka, Hirosato (University of California, Davis), and Herman J. Phaff . Enzymatic hydrolysis of yeast cell walls. I. Isolation of wall-decomposing organisms and separation and purification of lytic enzymes. J. Bacteriol. 89: 1570–1580. 1965.—A number of microorganisms, able to decompose and grow on yeast cell walls, were isolated from soil. These isolates demonstrated various types of attack on yeast walls. A bacterium, identified as Bacillus circulans , and a species of Streptomyces produced clear, lysed zones when grown on an agar medium containing baker's yeast cell walls. The streptomycete formed glucanase, mannanase, and protease, but B. circulans produced only glucanases. Purified mannan could be prepared from the culture fluid of B. circulans grown on baker's yeast cell walls. In a liquid, mineral medium, extracellular lytic enzyme production by B. circulans was optimal after 3 days of aerobic growth at 30 C with 0.5% baker's yeast cell walls as the carbon source. Twelve other carbon sources were ineffective as inducers. Among a number of polysaccharides tested, the crude enzymes of B. circulans hydrolyzed only β-1→3 glucan (laminarin) and β-1→6 glucan (pustulan), both by a random mechanism, to a mixture of dimer and glucose. The β-1→3 and β-1→6 glucanases were separated from each other by diethylaminoethyl cellulose column chromatography. Water-soluble oat glucan, which contains in the linear chain both β-1→3 and β-1→4 bonds, was also hydrolyzed by the bacterial β-1→3 glucanase. The products of this reaction indicated that this enzyme hydrolyzes β-1→3 or β-1→4 glucosidic linkages, provided the β-glucopyranosyl units composing these bonds are substituted in the 3 position by another glucose unit.