It has been reported that purple non-sulfur bacteria is
required NaHCO3 for supporting VFA uptake through the cell
which could increase the microbial growth resulting in a significant
hydrogen production [24]. As the nitrogenase enzyme
has driven hydrogen producing activity of photo non-sulfur
bacteria is strongly positive effect on some nitrogen source,
yeast extract, which has showed to have a relatively effect on
nitrogenase activity, as well as increasing in cell concentration
[25]. Results of this study showed that supplementation of
yeast extract and NaHCO3 could increase the cell concentration
but not hydrogen production. A similar result was also
reported by Xu et al. [25].