Biosynthesis of endochitinase of Serratia marcescens

The growth of a mutant strain of Serratia marcescens with high chitinase ac tivity and the biosynthesis of endochitinase by this strain were investigat ed. The study was carried out using semisynthetic culture medium without in ducers and culture medium containing colloidal chitin as a sole nitrogen an d carbon source, with and without mitomycin C. The mutant strain, unlike th e native one, was shown to produce endochitinase and to secrete the enzyme into the medium during the growth on culture medium without the inducers, c hitin and mitomycin C. During growth on the medium with chitin the mutant s train differed from the native one with a short lag-phase of growth, the ea rly appearance of endochitinase in the culture liquid and a high level of e ndochitinase activity. The difference between the strains disappeared after the addition of mitomycin C, an inducer of the cell SOS-response, to the c ulture medium containing chitin. Specific endochitinase activity of S. marc escens mutant strain grown on various culture media had two maxima, namely at the beginning and at the end of the stationary phase. Mitomycin C increa sed the specific activity in a second peak of endochitinase activity during the growth of the mutant strain.