Isolation and Characterization of a Marine Ice-nucleating Bacterium, Pseudomonas sp. KUIN-5, Which Produces Cellulose and Secretes It in the Culture Broth

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A novel marine ice-nucleating bacterium, KUIN-5, was isolated from a marine algae, Monostroma latissum. Strain KUIN-5 was identified as a Pseudomonas sp. from its characteristics and taxonomics; the optimum temperature and pH for its growth were 25℃ and 6.0, respectively. When strain KUIN-5 was aerobically cultured in Carlucci-Pramer medium (pH 6.0) for 50 h at 25℃, the highest ice-nucleating activity of the cells among the media for marine bacteria was obtained, and the ice-nucleating temperature, T_<50>, was indicated to be -3.2℃. Also, the optimum concentration of NaCl for the growth in this medium, which was prepared with distilled water instead of seawater, was 2.0% (w/v) and then the ice-nucleating activity was inversely proportional to the NaCl concentration. Moreover, when strain KUIN-5 was cultured in Davis medium under optimum conditions, it produced insoluble polysaccharide (IPS) in the culture. The maximum amount of IPS production by strain KUIN-5 was 84.5 mg/ml of medium under optimum conditions. Therefore, this IPS was isolated and could be identified as cellulose, based on TLC or HPLC of the acid hydrolysate, and GC-MS of the acetylated polyalcohol prepared by periodate oxidation and Smith degradation of this polysaccharide. This is the first report of cellulose production by a marine ice-nucleating bacterium.
1996-09-23