oa High-Temperature Biotransformation for Biohydrogen Production in Hydrocarbon-Rich Aqueous Media

High-temperature biotransformation in underground environments promotes specialized thermophilic microbial communities, including Thermotoga species, which are promising for biohydrogen production. Hydrocarbon-rich environments, such as produced water from oil and gas extraction, contain high levels of hydrocarbons, heavy metals, and pollutants, influencing microbial activity and hydrogen production.

This study examines the impact of hydrocarbons, specifically n-alkane (nC16) and aromatic (toluene), on Pseudothermotoga elfii growth and hydrogen production when co-digested with glucose. Batch fermentation experiments in a modified DSM 664 medium assessed microbial response to different hydrocarbon concentrations (1–10 g/L). Gas composition was analyzed using MicroGC 990.

Results show that nC16 delays hydrogen production at 1 g/L, inhibits it at 5 g/L, and completely suppresses it at 10 g/L due to competitive inhibition. P. elfii exhibits low tolerance to toluene, with even 1 g/L significantly reducing hydrogen output due to toxicity. CO2 and H2S were also detected, with CO2 produced via acetogenic fermentation and H2S from sulfate reduction.