Growth and acetic acid production characteristics of a new strain AX2 falling within hydrogen-producing acetogens

Among the bacteria colony in anaerobic digestion process, hydrogen-producing acetogens connect acidogenic fermentation bacteria with methanogens in functional niche. However, few pure cultures of hydrogen-producing acetogens have been obtained and knowledge about their physioecologic characteristics is little. Strain AX2, a new hydrogen-producing acetogen, belongs to Staphylococcus had been separated from anaerobic activated sludge. Its physioecologic character was investigated by batch culture. The acetic acid yields of AX2 in culture mediums of butyric acid and propionic acid with concentrations of 2.4 g/L and 2.31 g/L reached 278 mg/L and 222 mg/L, respectively. It had an excellent multiplication speed at pH of 7.0 and the temperature of 35°C, using ammonium chloride as the inorganic nitrogen source. The result indicates that AX2 has a strong capability to convert propinoic acid and butyric acid into acetic acid.