Enzyme formation by a yeast cell wall lytic Arthrobacter sp.: formation of \(1,3)-glucanase

The kinetics of \-1,3-glucanase (EC 3.2.1.39; 1,3-\-d-glucan-glucano-hydrolase) formation by a yeast cell wall lytic Arthrobacter species was studied. Yeast glucan as a substrate yielded 360 units (U)/l, but it appeared to be unsuitable for fermentation purposes because of its insolubility and its residual content of glycogen. Growth on water-soluble \(1,3)-glucan [maximum specific growth rate (µmax)=0.19 h−1] was governed by different saccharides liberated by enzyme action on glucan. Enzyme formation was repressed by glucose and derepressed by its restricted availability during late exponential and stationary growth. At least 380 U/l of \(1,3)-glucanase were formed. Lactose and lactulose were detected as precursors of potent inducers for \(1,3)-glucanase, the first being a cheap and easily available substrate for large-scale cultivations. Growth rates were reduced (µmax=0.18 h−1 and µmax=0.13 h−1, respectively), enzyme synthesis occurred only during post-logarithmic growth. The \(1,3)-glucanase levels (260 U/l) formed were comparable to that attained with glucan as a substrate. In continuous culture no enzyme was formed under steady-state conditions but it occurred during transient states after shifting the dilution rate to lower values.