Biohydrogen production by bacteria isolated from manures of three different bovines using synthetic starch wastewater as substrate

Aims: This study aimed at investigating the various hydrogen-producing bacteria isolated from three different bovine manure samples (dairy cow, feedlot cow and free grazing cow manures). Methodology and results: Nutrient broth (NB) and Reinforced Clostridium medium (RCM) broth were used for the isolation of facultative and strict anaerobic bacteria. The isolates were subjected to batch fermentation to determine their capability to produce hydrogen (H2) using synthetic starch wastewater as substrate in 60 mL serum bottles. Biogases of interest (hydrogen, carbon dioxide, methane) produced were analyzed using a Residual Gas Analyser (RGA), which is a mass spectrometry-based analytical system. A total of 52 isolates were obtained of which 13 of the isolates showed the ability to produce H2, with the NF6 isolate having the highest production of 6.85 × 10^-4 % partial pressure [% (pp)]. Conclusion, significance and impact study: From this study, culturable hydrogen-producing bacteria were successfully isolated from the three bovine manures. The results give an insight on the types of H2 producing bacteria present in the manure samples. These isolates will be useful for the further studies of H2 production using waste sources as substrates. The production of H2 by NF6 isolate will be optimized by varying parameters during the batch fermentation.