低温兼性厌氧纤维素降解菌系的选育

Study on breeding and characteristics of cold-active facultative anaerobic cellulase strains

经过25代限制性继代培养,选育出一组稳定的低温兼性厌氧纤维素降解菌系(X1),其优势菌群为短杆菌。X1最适生长温度为20℃,适宜生长溶氧量(DO)范围为0.04～0.09 mg.L-1,在含0.2%稻秸的改良PCS培养液中静置培养7 d,Cx酶(内切葡聚糖酶)、C1酶(外切葡聚糖酶)、β-葡聚糖苷酶活分别为18.7、54.3、17.8 U.mL-1;稻秸、玉米秸、滤纸降解率分别为55.3%、64.6%、94.3%;稻秸降解液主要产物为乙酸、丙酸、丁酸,其含量分别为0.656、0.168、0.128 g.L-1。

In this article, a cold-active facultative anaerobic cellulase strains named Xl was isolated, with optimum growth temperature 20℃. When Xl performed in improved PCS liquid medium with 0.2% rice straw that was the only carbon source, it showed that the cellulase activity of Cx, C1 and/3-glucanase were 18.7, 54.3 and 17.8 U·mL-1, respectively, and the degradation rate of rice straw, corn stalks and filter paper were 55.3%, 64.6% and 94.3%, respectively. The main liquid phase products were volatile fatty acid （VFA）, which contents were 0.656, 0.168 and 0.128 g·L-1, respectively, and which can be used as precursors of methane biosynthesis.