Optimization of biohydrogen production by Enterococcus SP. NF6 using starch as substrate

Abstract

The rising gap between the demand for fossil fuel-based energy and insufficient energy supply has led to the vast investigation of potential alternative clean energy, biohydrogen. In this study, starch utilizing bacteria Enterococcus sp. NF6 was isolated from cow manure; the effective starch utilization and biohydrogen production of the biocatalyst were investigated. To investigate the optimum conditions for biohydrogen production, batch fermentations were conducted by optimization of physicochemical parameters using one factor at a time (OFAT) method using Modified Reinforced Clostridial Media (MRCM) as fermentation media. Batch fermentations were carried out at several temperatures (30°C, 37°C & 45°C), initial medium pH (5.5, 7.0, 8.0 & 9.0) and initial substrate concentration of (0.5 g/L, 1 g/L & 3g/L). The highest biohydrogen production obtained at pH 5.5, incubation temperature of 37°C, and initial substrate concentration of 1g/L. These conditions, the biohydrogen production rate is 0.23 mL/H, with 100% of substrate utilization, 0.0790 h-1 of specific growth rate and maximum biohydrogen production of 1.85 mL. The outcome suggests the potential use of Enterococcus sp. NF6 for biohydrogen production in a single culture system.