产乙酸复合菌系Th3培养及其在沼气厌氧发酵中的应用

为有效提高厌氧发酵过程中乙酸转化率和甲烷产量,将CD-2(Clostridium sordellii)、ZY-3(Clostridium bifermentans)和ZQ-1(Clostridium butyricum)3株利用不同底物的产乙酸菌混合培养,人工构建一个高效产乙酸复合菌系Th3,通过试验确定其最佳发酵条件为:初始pH值为7.0-8.0,按ZQ-1、ZY-3、CD-2顺序接种,CD-2:ZY-3:ZQ-1接种比例(体积比)为1:2:1,总接种量6%,30°C静置培养,乙酸产率达0.65g/(L·d)。经过代谢稳定性测定,Th3连续培养10代,乙酸产量维持稳定。复合菌系Th3应用于室内沼气发酵,(26±1)°C,在发酵初期和中期加入复合菌系Th3均能显著提高沼气日均产气量和产气率,初期添加可缩短发酵启动时间2～3d。在发酵末期加入复合菌剂对整个发酵产气过程没有显著影响。该研究不仅为构建高效微生物菌剂、提高厌氧发酵效率和发酵过程优化提供基础参数,而且表明该复合菌在沼气生产中有一定的应用价值。

Culture of acetogenic complex strains Th3 and its application in biogas production

In order to improve conversion rate of acetic acid and methane yield in anaerobic digestion,an atificial composite system Th3 was constructed by mixing three strains of acetogenic bacteria CD-2(Clostridium sordellii),ZY-3(Clostridium bifermentans) and ZQ-1(Clostridium butyricum).The experimental results showed that the optimum fermentation conditions of Th3 were as follows:initial pH was 7.0-8.0,sequence of three bacteria inoculation was ZQ-1,ZY-3 and CD-2,inoculation ratio was 1:2:1,and inoculum was 6% of effective volume.At the same time,the acetic acid yield was observed as high as 0.65 g/(L·d) at 30°C with static culture.The metabolic process of Th3 was proved to be very stable within ten generations.At(26±1)°C,the daily biogas production and productivity were improved significantly after Th3 addition in the initial and medium fermentation,and the start-up phase was shortened by 2-3 days.But the biogas process had no significant change when Th3 was added at the late stage of fermentation.The research can provide a reference for the complex strains construction,anaerobic digestion efficiency improvement and optimization of fermentation process and has an application value in biogas production.