Screening Of High Chitin Deacetylase Producing Strain And Study On Its Optimization Of The Fermentation Conditions And Fundamental Enzymatic Properties

Chitosan is the unique of natural alkaline polysaccharide as yet. Chitosan have extensive application value, huge capacity of product development and market promotion in the field of medical, textile, food, healthcare, dyeing, cosmetics, treatment of wastewater. Chitin deacetylase (CDA), is the enzyme that catalyzes the conversion of chitin to chitosan by the deacetylation of N-acety-D-glucosamine residues, distributed mainly in some Zygomycetes fungi. Chitin deacetylase could produce chitosan instead of concentrated alkaline method at present. This method can resolve problem such as environment pollution and produce high quality chitosan. In this paper, a high productivity chitin deacetylase strain Z7 was screened and maked further study of the fermentation condition, properties of fundamental enzymologic, which preservation number is CSUFT F14. This study establishes a good foundation for industrial production of chitosan.(1) Screeing and identification of high chitin deacetylase producing Strain. In this paper 36 strains of productivity chitin deacetylase was screened at soil of river shoal beach and ruins of shrimp processing factory by color reactions of 4-nitroacetanilide.9 strains of high productivity chitin deacetylase was screened by the capacity of color reactions. A high-producing strain named Z7 was obtained from preliminary screening in the secondary screening by fermentation, which preservation number is CSUFT F14. On the basis of the criteria of Begrey's Manual of Systematic Bacteriology and the analysis of sequence of 16s rDNA, strain Z7 was identified as Bacillus amyloliquefaciens.(2) Study on high chitin deacetylase optimization of the fermentation conditions. The culture condition of shaking flask batch fermentation of strain Z7 was studied by single factor method in this paper. The best culture condition was confirmed:seed age 10h,37℃, pH6.0, 160r/min, culture 28h with the20% volume of liquid. By using Plackett-Burman(P-B) design, Box-Behnken design and response surface analysis, the optimum fermentation medium formula were confirmed:chitin 10g/L,starch 25g/L, yeast extract 10g/L, MgSO4 0.25 g/L, K2HPO4 0.3 g/L, NaCl 5g/L, under this condition the chitin deacetylase activity reached 27.48U/mL.The growth association type was confirmed by the comparison of chitin deacetylase activity and growth curve in the optimum fermentation medium formula and the best culture condition.(3) Study on high chitin deacetylase fundamental enzymatic properties. The results of fundamental enzymatic properties of chitin deacetylase producing from strain Z7 show that, the optimum temperature of strain Z7 was 40℃, the optimum pH was 6.5, under the concentration of 1mmol/L, Mg2+, K+, Ca2+ and Fe2+ had activation effect, of which the strongest activation effect was Mg2+. Pb2+, Cu2+ and Mn2+ had inhibitory effect, of which the strongest inhibitory effect was Mn2+.