Comparative evaluation of fermentative hydrogen production using Enterobacter cloacae and mixed culture: effect of Pd (II) ion and phytogenic palladium nanoparticles.

Palladium nanoparticles (PdNPs) were synthesized from PdCl2 using Coriandrum sativum leaf extract. The transmission electron microscopy (TEM) images confirm that the formation of PdNPs was mainly spherical in shape, with an average size of 87 nm. The influence of the PdCl2 and synthesized PdNPs on fermentative hydrogen production from glucose using Enterobacter cloacae and mixed culture was evaluated. In PdCl2 supplemented experiments, the hydrogen yields of E. cloacae and mixed culture were 1.39 ± 0.07 and 2.11 ± 0.11 mol H2/mol glucose, respectively, with 5.0 mg/L of PdCl2. The resulting hydrogen yield (P < 0.05) was lower than that of the control experiment (without supplementation), due to the soluble metabolites shift. However, the highest hydrogen yields of E. cloacae and mixed culture were 1.48 ± 0.04 and 2.48 ± 0.09 mol H2/mol glucose, respectively at 5.0 mg/L of PdNPs supplementation. The enhancement of biohydrogen production using mixed culture was significantly higher than that of E. cloacae as the same concentration of PdNPs.