Experimental Optimization of Green Hydrogen Production from Phototrophic Bacteria Rhodobacter sphaeroides

Abstract

Background and Objective: This study utilizes Rhodobacter sphaeroides bacteria for the photoproduction of hydrogen under various cultural conditions. R. sphaeroides was isolated from sewage water. We have examined different carbon and nitrogen sources for hydrogen production and further established the conditions for optimum hydrogen production by R. sphaeroides. Methods: The cumulative hydrogen produced by the bacteria at various intervals of time was measured using a Gas Chromatograph. Initially, by classical one factor at a time method, it was found that Benzoate and Glycine promote higher amounts of hydrogen production under anaerobic light conditions after 96 h. Results: The production was also observed to be enhanced in the presence of growth factors B12. Further, the Response Surface Methodology (RSM) was employed to optimize the hydrogen production. The first level of optimization was done using Box-Behnken Design (BBD) followed by Central Composite Design (CCD) method. The maximum production of hydrogen achieved by BBD and CCD was 6.8 ml/30 ml and 8.12 ml/30 ml, respectively. The significant model predicted is a quadratic model with R2 value 0.9459. Conclusion: Moreover, work presented here suggests an environment-friendly approach of harvesting H2, which could meet energy demand as clean fuel via the green route.