Note: Physiological aspects of the growth of the lactic acid bacterium Tetragenococcus halophila during Indonesian soy sauce (kecap) production

The lactic acid bacterium Tetragenococcus halophila is the dominant species in Indonesian soy mash. Tetragenococcus halophila growing in continuous an d retention cultures under defined glucose-limited conditions showed a swit ch from homolactic (only lactate produced) to mixed acid fermentation (two formate, one acetate and one ethanol formed per glucose) at low growth rate s, However, despite low concentrations of sugars present in soy mash and sl ow growth, no sn itch to mixed acid fermentation was observed during growth in so mash. The absence of mixed acid fermentation could not be explained by changes in pH or lactate concentration during growth, indicating that gr owth in soy mash is not energy-limited. Despite the absence of mixed acid f ermentation, an obvious production of acetate, an important so-c mash compo nent, is observed in soy mash. The possibility that soy mash components act ing as hydrogen acceptors could account for this phenomenon is discussed.