Isolation, chemical characteristics and immunity activity of an extracellular polysaccharide EPS I isolated from Antarctic bacterium Pseudoalteromonas sp.S-15-13

A new extracelluar polysaccharide （EPS） was isolated and purified from Antarctic bacterium S-15-13, identified as Pseudoalteromonas sp. After being separated and purified by DEAE-Sephadex A-50 ionexchange and Sephadex G-100 gel chromatography, two mains fractions （EPS I and EPS Ⅱ ） were ob-tained. EPS I was composed of mannose, glucose and galactose with a molecular weight of 23kDa and EPS Ⅱ was composed of mannose only with a molecular weight of 62kDa. The effect of the polysaccharide EPS I on the cellular immune response of mice was investigated. Results demonstrated that EPS I could markedly facilitate lymphocyte proliferation, and might be a strong immunomodulator.

响应面法优化产琼胶酶南极菌Pseudoalteromonas sp.NJ21的发酵条件

采用响应面法对1株高产琼胶酶的南极海冰菌Pseudoalteromonas sp.NJ21的发酵条件进行优化。首先分别以温度、pH、不同碳源、不同氮源、不同金属离子作为唯一变量进行单因素实验,筛选出对酶活有显著影响的单因素取值范围;参考单因素实验结果,采用Plackett-Burman实验设计筛选出影响酶活主要因素,再利用Box-Behnken设计及响应面分析法进行回归分析以确定最佳发酵条件。结果表明,D-甘露糖、蛋白胨、CaCl2和培养温度与酶活存在着显著的相关性,通过求解回归方程得到Pseudoalteromonas sp.NJ21的最佳培养基组成为D-甘露糖5.52g/L;蛋白胨7.4g/L;CaCl25.84mmol/L;最佳发酵温度为15℃;优化后发酵液中琼胶酶酶活由3.5U/mL提高到25.76U/mL,比优化前提高了6.36倍。