反硝化细菌的筛选及培养条件的研究

Screening of Denitrifying Bacteria and Determination of the Culture Conditions

从45个反硝化细菌(denitrifyingbacteria)菌株中筛选出具有较强反硝化作用能力的菌株,并对目的菌株的最适培养基、生长温度及好气性进行了测定,以自动化学分析仪检测Giltay液体培养基中的含氮量,测定了菌株的反硝化作用能力。结果表明,在45个供试菌株中,B88和B237菌株能够较好地降解培养基中的硝酸盐和亚硝酸盐,产气早,速度快,3～4d产气达到高峰,含氮量明显降低,表明其反硝化作用能力较强。B88和B237菌株是好气性的,生长受氧气供应量的限制,CO2含量(20%)的提高,对菌株的生长具有较强抑制作用。在牛肉浸膏蛋白胨培养基、反硝化细菌培养基、YB培养基等培养基中,YB培养基最适合B88和B237菌株生长。B88和B237菌株最适生长温度为30℃,在YB培养基中生长的最高浓度:B88为6.1×108个·mL-1;B237为1.54×108个·mL-1。

The denitrification function of denitrifying bacteria depended on two substances, nitrate reductase and nitrite reductase induced by nitrate and nitrite respectively. The denitrifying process must be under the condition with nooxygen or little oxygen supplied. The intensity of denitrification was determined by the method of Giltay medium, and dilution plate method was used to determine the optimum medium, aerobic characteristic and best growth temperature for screened bacterial strains. Two strains with high denitrification were screened out of 45 denitrifying bacteria. B88 and B237 degraded nitrate and nitrite much better, produced gas earlier and faster than other strains. B88 and B237 were aerobic and the growth was restricted by oxygen supply under no denitrifying process. The increase of CO2 content had stronger inhibition on the growth of both strains. The growth speed of different denitrifying bacteria varied with medium and temperatures. Among the three medium often used for denitrifying bacteria, nitrate medium, denitrifying bacteria medium and YB medium, YB medium was the optimum. The best growing temprature for the two srrains was about 30℃. Each strain had its own highest density in certain medium, on rotary shaker in YB medium, thehighest densities of B88 and B237 were 6.1×108·mL-1 and 1.54×108·mL-1, respectively.