针对8株已知有褐藻胶降解酶活性的菌株,以褐藻酸钠为唯一碳源,驯化培养后筛选得到一株高效降解菌中华黄海杆菌QM42.经过发酵培养实验,确定其最佳产酶条件(w/v):以蛋白胨为氮源,以褐藻酸钠为碳源,褐藻酸钠浓度0.4％～0.7％,培养盐度5％～7％,培养初始pH值为7,培养温度31℃,150r/min摇床发酵72h,粗酶液酶活力达到9.74U/mL.

A screening work was carried out to get marine bacterium with high alginate lyase activity by using alginate as sole source of carbon.Strain QM42 was selected for further studies among the 8 alginate-degrading bacteria strains.Results showed that the optimal carbon and nitrogen sources for marine bacterium QM42 to produce extracellular alginate lyase were alginate and peptone,respectively.The optimal concentration of carbon source was 0.4%~0.7%(w/v).The culture temperature was 31℃.The initial pH value of the liquid medium was about 7,and the salinity was 5%~7%.The optimal harvest time for extracellular alginate lyase was about 72h with 150r/min rotation.Under such conditions the marine bacterium QM42 could produce 9.74U/ml alginate lyase in crude fermentation medium.