Chiang Mai Journal of Science

     This study investigated the upper mesophilic temperature acclimation of halophilic, hydrogen-producing bacteria from salt fields, focusing on microbial abundance changes during dark fermentation. Genomic techniques, including PCR-denaturing gradient gel electrophoresis (DGGE) and next-generation sequencing (NGS), were used to profile the microbial communities. At 48°C, Halanaerobacter lacunarum showed significant abundance, correlating with increased hydrogen yield, suggesting its role in hydrogen production. While a decrease in H. lacunarum and Halanaerobium fermentans dominance was observed at 42°C due to other bacterial species’ growth, their dominance increased notably to 45°C and 48°C. This study highlights the adaptation potential of Halanaerobium sp. and other halophilic bacteria to upper mesophilic temperatures for hydrogen production. The findings emphasize optimizing temperature and pH conditions to maximize hydrogen yield during high-salt dark fermentation.