Biohydrogen production using native carbon monoxide converting anaerobic microbial consortium predominantly Petrobacter sp.

• Microbial CO conversion to H2 is promising for efficient syngas utilization.
• Biohydrogen production by anaerobic microbial consortia involved Petrobacter sp.
• Biohydrogen production was affected mainly by temperature and Fe2+ concentration.
• Biohydrogen production value obtained is superior compared to other literature reports.

In this study, anaerobic mixed microbial consortium isolated from a local sewage treatment plant in Guwahati, India, was used to convert carbon monoxide (CO) to hydrogen. The consortium was initially grown in acetate containing medium and later acclimatized to utilize CO as the sole carbon source for hydrogen production. By 16S rDNA analysis, the consortium was identified to be predominantly Petrobacter sp. Statistically designed experiments were then applied to optimize the CO conversion and hydrogen production by the anaerobic mixed consortium. To evaluate the significant factors that influenced the biohydrogen production, Plackett–Burman screening design of experiments was applied, which revealed that temperature and Fe2+ influenced the most on hydrogen production with P values less than 0.05 each. The effect due to pH and Ni2+ was less with P values 0.120 and 0.132, respectively. Concentration of Fe2+ and Ni2+ in the medium was then subsequently optimized by using Central Composite Design (CCD) of experiments followed by response surface methodology (RSM) which yielded the optimum value of 213 mg/L for Fe2+ and 2.2 mg/L for Ni2+. At these optimum conditions, 60.8 mol hydrogen production was achieved which was 8% higher than that observed from the screening experiment.