一株新型同型产乙酸菌Clostridium sp.的自养和异养生长特性

Autotrophic and heterotrophic characteristics of a novel acetogenic Clostridium sp.

【背景】同型产乙酸菌是一类利用乙酰辅酶A途径固定CO_2合成自身细胞物质并生成乙酸、乙醇等代谢产物的厌氧菌群,其分布广泛、种类繁多且代谢多样。深入研究同型产乙酸菌菌株的代谢能力及特性,对探索该种群的生理生化特性及其环境作用至关重要。【目的】研究一株同型产乙酸菌Clostridium sp. BXX的最适培养条件及其自养与异养生长特性。【方法】设置BXX菌株培养温度10-55°C、初始pH 6.0-9.0、NaCl浓度0-2.0%、不同氮源,测定菌体细胞含量和产物生成浓度,确定菌株最适培养条件。研究BXX菌株分别以H_2/CO_2、合成气、CO、葡萄糖、1,2-丙二醇、甲酸钠、乙二醇甲醚、甘油、丙酮酸和乳酸为底物时的底物消耗、产物生成、菌体细胞含量和pH等,探究其自养和异养生长特性。【结果】BXX菌株的最适培养温度为30°C,初始pH为7.0,NaCl浓度为1.0%,氮源为酵母粉。BXX菌株能以H2/CO2、合成气、葡萄糖、1,2-丙二醇、甲酸钠、乙二醇甲醚和甘油为底物生长,不能以CO、丙酮酸或乳酸为底物生长。【结论】BXX菌株既能自养生长产乙酸,又能异养生长产乙醇。BXX菌株是乙酸发酵的优良菌种资源,有较好的工业应用潜力。

[Background] Acetogens are a group of anaerobic bacteria that use Wood-Ljungdahl pathway for the assimilation of CO2 into cell carbon and production of acetate or ethanol. They are widely distributed in nature and highly phylogenetically and metabolically diverse. The investigation on the metabolic capabilities of acetogenic bacteria is important to understand their physiological and biochemical characteristics as well as environment roles. [Objective] This study aims to optimize the culture conditions and understand the autotrophic and heterotrophic characteristics of a strain of novel acetogenic bacterium Clostridium sp. [Methods] The incubation was performed at temperature of 10-55 ℃, initial pH of 6.0-9.0, NaCl concentration of 0-2.0% or with different nitrogen source to optimize the culture condition of stain BXX by determining the cell and product concentration. The autotrophic or heterotrophic growth characteristics of strain BXX were studied by measuring substrate consumption, product generation, bacterial concentration and pH with CO, syngas, H2/CO2, glucose and other organic matters as substrates. [Results] The optimum temperature, initial pH, NaCl concentration and nitrogen source of strain BXX was 30 ℃, 7.0, 1.0% and yeast extract, respectively. Strain BXX grew on H2/CO2, syngas, glucose, 1,2-propanediol, sodium formate, 2-methoxyethanol and glycerol, and did not grow on CO, pyruvate or lactate. [Conclusion] Strain BXX grew autotrophically to produce acetate and grew heterotrophically to produce ethanol. Strain BXX was an excellent strain resource for acetate fermentation and had good potential of industrial application.