The organic acids in the DFE can be used as a substrate for
production of hydrogen by the photosynthetic bacteria.
However, the organic acids obtained in this study were not
suitable for Rps. palustris TN1 because the concentrations may
be too high that may cause a decrease in productivity and
yield [8]. So, evasion from the inhibitory effect of substrate
concentration could be obtained by diluting the DFE to
determine the optimum substrate concentration before
reutilization in photo fermentation [6]. The previous study of
Rps. palustris TN1 found that yeast extract and NaHCO3 had a
confidence level above 95%, indicating they are statistically significant factor for the hydrogen production (p < 0.05) with
the optimum concentrations of 2.30 g/L and 0.63 g/L, respectively.
Thus, hydrogen production on the dilution of DFE with
and without a supplementation of yeast extract and NaHCO3
were monitored.