中文摘要：

从窖泥中分离到一株能利用乳酸产丁酸的菌株BEY8,基于16SrRNA基因序列分析鉴定为梭菌属（Clostridium）.BEY8菌体生长和代谢乳酸的最适pH为5.5-6.0,当pH低于4.8或高于6.5,菌体均出现明显的生长和代谢延滞,但最终仍能完全将乳酸转化为丁酸;此外,当乳酸浓度达到156mM时,BEY8的生长及代谢同样出现延滞,且延滞时间随乳酸浓度的升高而延长,但最终都能完全将乳酸转化为丁酸,这些特性表明该菌有较强的环境适应能力及代谢稳定性.在pH4.8时,外加乙酸可显著缩短BEY8的生长延滞期,并提高其对乳酸的代谢速率,但乙酸不能作为菌体的唯一能源生长,而只作为电子受体参与代谢乳酸产丁酸.

英文摘要：

A lactate-utilizing bacterium BEY8 was isolated from a pit mud and it could produce butyrate from lactate.Based on phylogenetic analysis of 16 SrRNA gene sequences,the strain BEY8 should belong to the genus Clostridium.The optimal pH values for BEY8 growth and lactate metabolism were found to be 5.5-6.0,and the lag time was observed at pH 4.8and pH6.5,while lactate could be finally converted into butyrate as the main metabolic product.In addition,when the concentration of lactate was greater than 156 mM,the lag time was also observed,and the arrearage time prolonged with lactate concentration,but finally lactate could mainly be converted into butyrate as metabolic product.It was suggested that BEY8 has a potential to adapt to environment change,and the environmental factors do not affect the change of bacterial metabolic pathway.Furthermore,at pH4.8,the addition of acetate could significantly reduce the lag time of BEY8 growth and improve the metabolic rate of lactate,but acetate could not serve as the sole energy source for bacterial growth,instead of being the electron acceptor in the metabolism of lactate and butyrate production.