Synthesis of Extracellular Chitinase by Wild-Type B-10 and Mutant M-1 Strains of Serratia marcescens

Molecular weights of extracellular chitinases from wild-type B-10 (62, 54, 43, 38, and 21 kDa) and mutant M-1 strains of Serratia marcescens (62, 52, 43, 38, and 21 kDa) were estimated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. In the absence of chitin inductors, chitinolytic enzymes were not found in the culture liquid of B-10, whereas M-1 cells produced the chitinase complex (to 470 pU/cell). Crystalline chitin insignificantly stimulated the synthesis of chitinases with molecular weights of 62, 54, and 21 kDa by B-10 (up to 20 pU/cell), but caused oversynthesis of all chitinases by the mutant strain (up to 2600 pU/cell). Colloidal chitin induced the production of chitinases by cells of both strains. Two peaks of chitinolytic activity were observed during cultivation of strains B-10 (350 and 450 pU/cell) and M-1 (2200 and 2400 pU/cell). The first peak of cell productivity was associated with biosynthesis of the chitinase complex. The second peak was related to the synthesis of enzymes with molecular weights of 54, 43, 38, and 21 kDa (B-10) or 43, 38, and 21 kDa (M-1).