Screening, Identification And Optimization Of Fermentation Conditions Of A Chitosanase-producing Bacterium And The Characterization Of Chitosanase

Now, people pay much attention to chitosan and its degradation product due to the excellent physical characteristic and biological activity. In this study, we had isolated a high Chitosanase-producing bacterium K1from the soil of Qingdao seacoast by primary screening of plate specula and shaking cultivation. The optimizations of fermentation conditions were studied by Response Surface Methodology. The results showed that strain K1was identified as Mitsuaria sp.(GenBank receive No.: KC489157). The optimal producing chitosanase conditions of K1strain were powder1.0%chitosan,0.5%KNO3,0.22%KH2PO4,0.1%Na2HPO4,0.15%KCI,0.05%MgSO4-7H2O, initial pH6.5,100mL medium and3%(v/v) inoculation amount,25℃incubating temperature and160r/min for25hours. At the optimal cultural conditions, the maximum chitosanase activity of strain K1could reach11.56U/mL which was5times of primary strain. Due to strain Kl with lower fermentation temperature and lower fermentation time, so it would be the potentiality in industrial fermentation. In addition, the results of zymological properties showed that the optimum subtrate concentration of chitosanase is1.5%colloidal chitosan; The enzyme showed high activity between50℃and70℃(with the highest activity at60℃),while it manifested high thermal stability between20℃and30℃; The enzyme showed high activity with a range of pH4-6(with the highest activity at pH5.2),while the enzyme activity was relatively stable with a range of pH5.4-6; In addition, Ca2+、Mg2+、Mn2+could enhance the enzyme activity significantly, whereas Cu2+、Fe3+、Zn2+could inhibit the enzyme activity. The results of this study may provide the data and theoretical foundation for industrial manufacture of chitosanase enzymes with fermentation method.