Screening And Identification Of A Novel Chitosanolytic Bacterium And Analysis Of The Fermentation Products

A strain producing chitosanase was isolated from soil samples and identified as Acinetobacter sp. C-17. It is the only one Acinetobacter strain that can degrade chitosan reported so far. The optimal conditions for C-17 strain producing chitosanase were 30℃ incubating temperature, medium pH 7.0, 1% chitosan, 250ml Erlenmeyer flask containing 75-100ml medium and 10% amount of inoculation. The chitosanase activity of fermented broth was 1.7U/ml when Acinetobacter sp. C-17 was incubated in Erlenmeyer flask under the optimal conditions at 24h, and could reach to 2.8U/ml when it was incubated in 3L fermentor, which is the highest one among known chitosanase. The chitosanase from Acinetobacter sp. C-17 is an inducible and secreting extracellular enzyme, and was stable in the pH range of 4.0-10.0 and temperature under 40℃. Its optimal temperature and pH for hydrolyzing chitosan were 36℃ and 7.0 respectively. A chitosanase of Acinetobacter sp. C-17 was extracted by ammonium sulfate precipitation and acetate zinc precipitation. The molecular mass was estimated to be 35.4kD by SDS-PAGE. The physiological functions of Acinetobacter sp. C-17 fermented broth were also tested. The chitosan oligosaccharides in fermented broth could stimulate growing of Oryza sativa seedlings to a certain extent.