Waste-derived lactate medium for biohydrogen production by Clostridium drakei and its application to PEM fuel cells for electricity generation

Although hydrogen is a promising clean energy carrier, conventional production remains heavily dependent on fossil fuels. As one of alternative ways, microbial fermentation, especially microbial dark fermentation, which converts organic waste into hydrogen gas in the absence of light, could give benefits by waste conversion, continuous operation and high production rate. Therefore, this study aimed to evaluate and enhance hydrogen production by selecting Clostridium strains, designing efficient medium for waste based organic acid like lactate. Based on lactate utilization and growth test, Clostridium drakei, an acid-tolerant anaerobe was selected as the biohydrogen-producing strain. In design of experiment, Plackett–Burman screening identified glucose, peptone, and lactate as key components, and their concentrations were refined using a Box–Behnken design. The resulting novel JO medium enhanced hydrogen production by 3.6-fold compared to the conventional reinforced clostridial medium (RCM), with improved cell growth and biogas output. Even when hydrogen production using the waste supernatant containing 3 g/L of lactate was used in novel media, 151.56% higher than the original RCM, which was 30.24% lower than that of the chemically supplemented lactate condition, but still demonstrating its potential as an alternative substrate source. As further application, produced biohydrogen was applied in a proton-exchange membrane fuel cell to convert hydrogen into electrical energy, the current reached 25 ± 1 mA with the JO medium, representing a 2.94-fold increase over conventional medium. Overall, novel media composition can be used for efficient biohydrogen production C. drakei, which is frequently found in microbiota of biohydrogen production.