环境因素对琥珀酸放线杆菌Actinobacillus succinogenes CGMCC 1593发酵生产丁二酸的影响

Environmental Factors Affecting the Succinic Acid Production by Actinobacillus succinogenes CGMCC 1593

摘要:

琥珀酸放线杆菌是发酵生产有应用前景的生物基原料-丁二酸的微生物。本研究室从牛瘤胃中筛选获得一株琥珀酸放线杆菌Actinobacillus succinogenes CGMCC 1593, 分析了环境气体、pH、氧化还原电位(ORP)环境因素对琥珀酸放线杆菌A. succinogenes CGMCC 1593发酵生产丁二酸的影响。结果表明: CO2不仅提供了A. succinogenes CGMCC 1593发酵生产丁二酸的最佳气体环境, 也是发酵生产丁二酸的底物之一; MgCO3是A. succinogenes CGMCC 1593发酵过程较好的pH调节剂, 发酵过程维持pH7.1~6.2, 可满足菌体生长与产酸的要求; 发酵液初始ORP过低, 不利于菌体生长, ORP在-270 mV时对丁二酸产生有利。在菌体对数生长期结束时, 通过Na2S·9H2O降低发酵液ORP到-270 mV, 发酵48 h时可产丁二酸37 g/L, 摩尔产率达到129%。这对深入研究A. succinogenes CGMCC 1593发酵生产丁二酸具有参考价值。

Abstract:

Actinobacillus succinogenes is a promising candidate for the production of bio-based succinic acid. Previously, we isolated a succinic acid-producing strain Actinobacillus succinogenes CGMCC 1593 from bovine rumen. In this paper, the influence of the environmental factors such as gas phase, pH, ORP, on succinic acid production by A. succinogenes CGMCC 1593 was studied. The results showed that CO2 was the optimum gas phase for anaerobic fermentation of A. succinogenes CGMCC 1593 as well as one of the substrate for the succinic acid synthesis. Using MgCO3 as a pH regulator, the pH was maintained within 7.1–6.2 during the anaerobic fermentation for the cell growth and acid production of A. succinogenes CGMCC 1593. Our results showed that low initial ORP was disadvantageous for the growth of A. succinogenes CGMCC 1593 and an ORP of ?270 mV was demonstrated to be beneficial to the succinic acid production. By adding Na2S?9H2O to decrease ORP to ?270 mV at the end of exponential growth phase in batch culture of A. succinogenes CGMCC 1593, the succinic acid concentration reached 37 g/L and the yield of succinic acid was 129% at 48 h. This work might provide valuable information for further optimization of succinic acid fermentation by A. succinogenes CGMCC 1593.