中文摘要：

为构建一套乳酸合成丁酸的工艺,在开放体系中,驯化培养丁酸合成混合菌,并对发酵工艺条件进行系统研究和优化.首先通过单因素试验设计确定各因素的最佳水平范围.结果表明,p H值控制在5.5-7.5之间,乳酸浓度控制在20-40 g/L之间,外加乙酸浓度控制在1.5-3.5 g/L之间可以得到丁酸的最大产率.在此基础上,进一步对p H值、乳酸浓度和外加乙酸浓度进行三因素三水平的Box-Behnken试验设计及响应面法分析,以丁酸产率作为响应值,探究影响丁酸产率的各因素之间相互作用.通过方差分析显著性及求解回归方程得到最优发酵工艺条件：在p H值为6.72,乳酸浓度为27.83 g/L,外加乙酸浓度为2.79 g/L时,丁酸最高产率理论可达2.47 g L~（-1） d~（-1）.验证试验得到的结果是丁酸产率为2.43g L~（-1） d~（-1）,与预测值接近,较优化前产率提高了47.27%.此外,利用高通量测序技术（Miseq）对微生物群落结构进行分析,发现混合微生物中占优势的菌群是Clostridium sensustricto、Lactobacillus与Clostridium IV,其丰度分别为69.35%、15.41%与10.05%.利用本发酵新工艺能够得到相对稳定的丁酸产率,因此在工业中具有广阔的应用前景.

英文摘要：

This paper reports a new process that can produce butyrate from lactate using mixed culture.In order to reduce the cost of butyrate fermentation as well as improve the yield of butyrate,we also investigated optimization of the fermentation conditions.First,functional mixed culture was acclimated by fed-batch fermentation in a designated reactor.Second,the optimal range of various factors were determined by conducting single factor experiments.Third,optimal conditions were obtained by using response surface methodology about Box-Behnken design.Finally,microbial community structure was analyzed by using high-throughput sequencing technologies.The single factor experiments showed the optimal range of p H as between 5.5 and 7.5,lactate concentration as between 20 g/L and 40 g/L,and additional acetate concentration as between 1.5 g/L and 3.5 g/L.Response surface analysis found that the highest production rate of butyrate（2.47 g L-1 D-1） was achieved at p H 6.72 with lactate concentration of 27.83 g/L and acetate concentration of 2.79 g/L.Finally,high-throughput sequencing analysis indicated that Clostridium sensustricto,Lactobacillus and Clostridium IV were the dominant microorganisms,with abundance of 69.35%,15.41% and 10.05%,respectively.The new process of butyrate production from lactate with mixed culture may have potential for industrial production because the product rate is comparable to established fermentation systems.