褐藻酸降解菌株S3的筛选分离及培养条件和产酶能力

Screening and Cultivation Conditions of an Alginic Acid Decomposing Bacterium Gracilibacillus sp. S3

利用褐藻酸钠作为唯一碳源筛选分离得到1株具有高褐藻酸酶活性的菌株S3,初步鉴定为革兰氏阴性杆菌。对菌株S3培养条件进行优化,褐藻酸钠和蛋白胨为最佳碳、氮源,NaCl质量分数为2%,在22℃、pH值7.5条件下,发酵S3菌株18h,褐藻酸酶酶活最高。继而研究了稀土元素对海洋微生物的生长及产酶能力影响,发现某些低浓度的稀土元素对菌株S7产酶有一定的促进作用,其中0.1mmol/L硝酸铈促进作用最强,促进率约31.1%,另外0.1mmol/L硝酸镧对菌株S3产酶能力的促进率也达到16.6%,而高浓度的稀土元素均有强抑制作用。研究结果为海洋微生物褐藻酸酶的进一步开发利用打下基础。

The strain Gracilibacillus sp.S3 was isolated with alginate from the decaying of Laminaria japonica and identified as Gram negative bacilli.The culture conditions of the strain S3 were optimized.The alginate activity was the highest when the strain was cultured in the medium under the conditions of 22 degrees C,NaCl content of 2 percent,pH 7.5 for 18h using sodium alginate as carbon source and peptone as nitrogen source.Moreover,the effects of rare earth elements on the growth and the enzyme production capacity of marine microorganisms were studied.Result shows that low concentration of rare earth elements is beneficial to strain S3 enzyme production,while high concentration prevents strains S3 from growing or producing enzyme.It is proved that 0.1mmol/L of cerous nitrate has the maximum growth-promoting efficiency（31.1 percent）and 0.1mmol/L of lanthanum nitrate has a moderate efficiency（16.6 percent）.