Iron oxide treated Chlorella sp. for enhanced biomass and lipid content coupled to fermentative hydrogen production by Enterobacter aerogenes using hydrolyzate from pretreated biomass

In this study, iron oxide nanoparticles (IONPs) were employed as an efficient chemical additive to enhance the Chlorella sp. biomass growth and lipid content. A novel strategy was developed to promote biomass growth and lipid content. Treatment with 20 mg/L followed by an additional 40 mg/L concentration of IONPs increased biomass and lipid content of Chlorella sp. by 53% and 67%, respectively, compared with the control. The hydrolyzate of 20 mg/L IONPs treated biomass residues obtained after combined hydrolysis showed maximum reducing sugars content of 41% dry cell weight (dcw), which was further used as substrate for dark fermentative hydrogen production mediated by Enterobacter aerogenes. The optimized concentration of IONPs supplementation in the dark fermentation system yielded 2.6 mol H2/mol sugar with acetate as predominant end metabolite. Hence, the present study demonstrated that the IONPs supplementation was a suitable chemical catalyst for biomass and biofuel production.