초록
Escherichia coli produces molecular hydrogen (H<SUB>2</SUB>) from different carbon substrates like sugars, glycerol and some organic acids during mixed-acid fermentation. H<SUB>2</SUB> production in batch cultures during acetate utilization of different concentrations (1 g L<SUP>-1</SUP>-5 g L<SUP>-1</SUP> was used) was investigated at different pHs. H<SUB>2</SUB> yield in E. coli wild type cells was highest at the log growth phase in the presence of 5 g L<SUP>-1</SUP> acetate. Either at pH 7.5 or pH 6.5 H<SUB>2</SUB> yield was 5.07 mmol L<SUP>-1</SUP>. At pH 5.5, H<SUB>2</SUB> production was detected when 1 g L<SUP>-1</SUP>acetate was supplemented in the growth medium. Interestingly, in the presence of 1 g L<SUP>-1</SUP> acetate H<SUB>2</SUB> yield was highest at pH 6.5 compared to 2 and 5 g L<SUP>-1</SUP> concentrations. As acetic acid and glycerol are unavoidable constituents of various industrial or agricultural wastes, H<SUB>2</SUB> generation using the mixture of acetate (5 g L<SUP>-1</SUP>) and glycerol (10 g L<SUP>-1</SUP>) at different pHs was also investigated. The highest H<SUB>2</SUB> yield of 5.16 mmol L<SUP>-1</SUP> was detected at the log growth phase at pH 7.5. H<SUB>2</SUB> generation was continuously detected at pH 7.5 and pH 5.5 for 96 h of growth. These data can be applied to further enhancement of H<SUB>2</SUB> energy production biotechnology and to use different industrial or agricultural wastes where acetate and/or glycerol is present to produce H<SUB>2</SUB>.