Autotrophic and heterotrophic characteristics of a novel acetogenic Clostridium sp.

Abstract:

[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 °C, 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 °C, 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.

Key words:Clostridium, Acetogen, Autotrophic, Heterotrophic, Ethanol