Effect of phyto-fabricated nanoscale organic-iron complex on photo-fermentative hydrogen production by Rhodopseudomonas palustris MP2 and Rhodopseudomonas palustris MP4

Abstract Biosynthesis is a promising green method to produce hydrogen fuel. Different approaches have been used in this regard to enhance hydrogen yield, however, there is still a need to explore further. The current research is an effort to enhance hydrogen yield using nanoscale organic-iron (NO–Fe) complex. NO–Fe complex was synthesized using Eucalyptus viminalis leaf extract and was characterized by UV–Vis, FTIR, XRD, FESEM, TEM and EDS. The NO–Fe complex was used as an iron source for the newly isolated photo fermentative Rhodopseudomonas palustris MP2 and Rhodopseudomonas palustris MP4 bacterial strains. FeSO4·7H2O was also used as a source of iron and compared with the effects of NO–Fe complex. Both the strains responded well to the NO–Fe complex and production of hydrogen was increased with increasing concentrations of NO–Fe complex. Highest yield of hydrogen was achieved by R. palustris MP4 (0.08 ± 0.01 mol-H2mol−1 of-succinate) when the NO–Fe complex was used at 5.0 mg L−1 concentration. The NO–Fe complex was more efficient than iron ions in enhancing bio-hydrogen production. The study revealed that phyto-fabricated NO–Fe complex is an efficient nutrient to improve hydrogen production by purple non-sulfur bacteria.