초록
Soil was used as seed without pretreatment for the fermentation of lactate in order to produce H<SUB>2</SUB>. When the pH was kept at a constant level, H<SUB>2</SUB> production occurred in three steps. The first was the production of small amounts of H<SUB>2</SUB> during the initial growth of the microflora. Then, after a reasonably long period of inactivity during the cultivation stage, a large amount of H<SUB>2</SUB> was produced in additional two steps. It was found that the reduction of the pH after the initial growth phase had a positive effect on the H<SUB>2</SUB> yield. After cell growth at pH 6 and cultivation at pH 5, a total H<SUB>2</SUB> yield of 154 mmol l<SUP>-1</SUP> was achieved. It was found that acetate was essential for the rapid H<SUB>2</SUB> formation. On the other hand, even small initial concentrations of butyrate impeded the H<SUB>2</SUB> formation.