Screening And Identification Of Chitinase-Synthesizing Marine Microbe And Optimizing Of Fermentation Condition

Thirty eight strains of bacteria producing chitinase, which included thirty two strains of bacteria, five actinomycetes and one fungi, were isolated from various samples of South sea.At present, the sequence of 16S rRNA gave a main basis on studying the systematic development of bacteria and building up the system of microbial taxonomy. This paper selected three strains of bacteria, which produced chitinase powerfully than other elses, and analyzed their 16S rDNA sequence based on the general shape-analysis and biochemical-physiological features. The results showed that they were identified as Escherichia sp. 0303, Agrobacterium sp. 0318 and Micrococcus sp. 0319. Subsequently, the phylogenetic tree was established.The research showed that the optimal conditions of fermentation of 0318 were as follows: using 20%(v/v) colloid chitin as the carbon source, 0.3% peptone-NaNO3 as the nitrogen source, 2.0% NaCl, 0.07% K₂HPO₄, 0.04% KH₂PO₄, 0.05% MgSO₄.7H₂O, 0.001% FeSO₄.7H₂0,175ml media in 500ml flask. Seeding size was 5%(v/v), seeding age 72 hours, initial pH value 6.5, culturing temperature 31°C, rotated speed 240 r/min, and incubated it for 96hours. The chitinase activity of fermented culture medium could reach to 0.49 U/ml under the optimal conditions. In additions, the kinetic models were also developed to describe the effects of chitin concentrations on specific growth rate, biomass productivity and chitinase production. (1). Kinetic model of effect of powder chitin concentration on specific growth rate.U = 0.1718S/[0.0495+S+(S2/1 .0036)]; (2). Kinetic model of effect of powder chitin concentration on biomass productivity.Y= 0.3822S/[0.0608+S+(S2/2.5929)];(3). Kinetic model of influence of colloidal chitin concentration on chitinase production. H_Chi=0.2530S/(2.2669+S)...