Screening and mutagenesis of a chitosanase-producing strain

Using chitosan as sole carbon source,a chitosanase-producing strain was isolated from soil samples.Its chitosanase activity was 0.59 U/mL.The strain was preliminarily characterized as a Bacillus sp.,designated as A.The strain A was then selected as the original strain by DES mutagenesis.After DES mutagenisis for 50 min,a mutant(designated as DES-4) was obtained with chitosanase activity of 1.60 U/mL,which was 2.7 times of that of the original strain.The mutant was transferred for 5 times and its chitosanase activity was stable.Results indicated that there existed close relation between the chitosanase production and growth cycle of the strain DES-4.Chitosanase activity of fermented broth increased while spores began to form in the cells.Maxium chitosanase activity was corresponding to fully formation of spores.