The separation of β-glucanases produced by Cytophaga johnsonii and their role in the lysis of yeast cell walls

Abstract

1. When Cytophaga johnsonii was grown in the presence of suitable inducers the culture fluid was capable of lysing thiol-treated yeast cell walls in vitro. 2. Autoclaved or alkali-extracted cells, isolated cell walls and glucan preparations made from them were effective inducers, but living yeast cells or cells killed by minimal heat treatment were not. 3. Chromatographic fractionation of lytic culture fluids showed the presence of two types of endo-β-(1→3)-glucanase and several β-(1→6)-glucanases; the latter may be induced separately by growing the myxo-bacterium in the presence of lutean. 4. Extensive solubilization of yeast cell walls was obtained only with preparations of one of these glucanases, an endo-β-(1→3)-glucanase producing as end products mainly oligosaccharides having five or more residues. Lysis by the other endo-β-(1→3)-glucanase was incomplete. 5. The β-(1→6)-glucanases produced a uniform thinning of the cell walls, and mannan–peptide was found in the solution. 6. These results, and the actions of the enzyme preparations on a variety of wall-derived preparations made from baker's yeast, are discussed in the light of present conceptions of yeast cell-wall structure.