Phytosynthesized iron nanoparticles: effects on fermentative hydrogen production by Enterobacter cloacae DH-89

Abstract

In recent years the application of metal nanoparticles is gaining attention in various fields. The present study focuses on the additive effect of 'green' synthesized iron nanoparticles (FeNPs) on dark fermentative hydrogen (H 2) production by a mesophilic soil bacterium Enterobacter cloacae. The FeNPs were synthesized by a rapid green method from FeSO 4 using aqueous leaf extract of Syzygium cumini. The synthesized FeNPs showed a characteristic surface plasmon resonance peak at 267 nm. The transmission electron microscopy images confirm that the formation of FeNPs was mainly porous and irregular in shape, with an average particle size of 20-25 nm. The presence of iron (Fe) in the synthesized FeNPs was confirmed by energy-dispersive X-ray spectroscopy. The comparative effect of FeSO 4 and FeNPs on batch fermentative H 2 production from glucose was investigated. The fermentation experiments reveal that the percentage and yield of H 2 in FeNPs supplementation were increased significantly than the control (no supplementation) and FeSO 4 containing media. The maximum H 2 yield of 1.9 mol mol −1 glucose utilized was observed in 100 mg l −1 FeNPs supplementation, with twofold increase in glucose conversion efficiency. Thus, the result suggests that FeNPs supplementation in place of FeSO 4 could improve the bioactivity of H 2 producing microbes for enhanced H 2 yield and glucose consumption.

Facile, one-pot biosynthesis and characterization of iron, copper and silver nanoparticles using Syzygium cumini leaf extract: As an effective antimicrobial and aflatoxin B1 adsorption agents

“…However increasing in the absorbance after addition of precursor solutions indicated the onset of particles formation. UV-Vis spectrum of Fe-NPs revealed characteristic SPR absorption peak at 262 nm (Fig 5A) and agreement with the previous study [35]. UV/Vis spectrum of Cu-NPs presented maximum SPR absorption peak at 572 nm (Fig 5B).…”

Nanoparticles in Biological Hydrogen Production: An Overview

“…Interestingly, FeNPs resulted in higher cell growth of E. cloacae DH-89. Thus, these results suggested that FeNPs enhance the metabolic process of E. cloacae DH-89 for H 2 production [58]. On the other hand, FeNPs at a high concentration of 400 mg/l showed lower enhancement of 38% in H 2 yield (1.23 mol/mol hexose) by a mixed bacterial consortium from glucose as feed [61].…”

“…metal ions. Recently, the NPs forms of these metals along with others including, activated carbon, Ag, Au, CNTs, Pd, Si and Ti also resulted in the profound effect of up to 6.7-fold on the H 2 production yield [27,29,45,48,49,51,55,58,62]. Here, the enhancement in the H 2 production is associated with NPs concentration and their properties.…”

“…At 5.0 mg/l PdNPs, 0.6 and 6.4% higher yield with [62]. On the other hand, Nath et al [58] showed the influence of green synthesized FeNPs using bark and leaf extracts of Syzygium cumini and Fe 2? ions at higher concentration of up to 200 mg/l on H 2 production by E. cloacae DH-89.…”

“…Primarily, in the presence of NPs H 2 producers shift intermediate metabolites towards higher ratio of acetate to butyrate and inhibition in the production of ethanol and propionate production. Among, the pure cultures, including C. butyricum CWBI1009, C. pasteurianum CH5, E. aerogenes ATCC13408, E. cloacae DH-89, E. cloacae and 811101 and R. palustris strains, E. cloacae DH-89 exhibited the maximum enhancement in H 2 yield up to 100% [58]. On the other hand, the mixture of Fe and Ni NPs were found to be more suitable to improve H 2 yield up to 200% using anaerobic sludge as a mixed culture [59].…”