Screening Of Chitinase-producing Bacteria Strains, Fermentation And Characterization Of The Chitinase

Chitin, the second most abundant natural polymer, is consisting of β-1,4-linkedN-acetyl-D-glucosamine(NAG). Approximately ten billion are produced by biologicalevery year. In spite of the great value of development, it is difficult to apply chitin forits characteristics. Hydrogen bonds are widespread in chitin, which makes it difficultfor chitin to dissolve in acid, alkali and many kinds of organic solvent.Chitinase can catalyze breakage of β-1,4glycosidic bond，breaking chitin intoNAG or oligosaccharide. Degradation of chitin can be simple in technology,environmental friendly in way of enzymolysis.With the purposes of screening and selecting an effectively chitinase-producingstrain,a strain is isolated from the samples. The optimal compositions of the mediumto produce chitinase are as follows: chitin powder0.5%、yeast powder2%、(NH4)2SO41.00%，K2HPO40.07%，KH2PO40.03%，NaCl1%，MgS04·7H2O0.15%.The optimal cultivation conditions are250ml flask containing100mLmedium，30℃incubating temperature and shaking cultivation at140r/min with pH6.0.After procedure of centrifugal effect, the fermented liquid is extracted byammonium sulfate and then the crude chitinase is produced. The optimal temperaturefor hydrolysis of chitinase is45℃and the optimal pH is6. It remains activity if it isput at25℃to45℃or pH5.5-7.5. The enzyme activity is slightly activated byMg2+and Zn2+,and Cu2+、Fe3+、Fe2+、Ca2+can inhibit the enzyme activity. This kindof chitinase can degrade chitin instead of starch and cellulose.