Enrichment of microbial consortium and performance evaluation for single cell protein production in hydrogen-mediated microbial electrosynthesis reactors

The exponential expansion of the global population has raised substantial concerns regarding potential food security crises in the foreseeable future, compounded by environmental degradation and greenhouse gas emissions associated with conventional agricultural practices. Fortunately, edible microbial protein has emerged as a promising sustainable alternative. Thereinto, hydrogen-oxidizing bacteria (HOB) coupled with microbial electrosynthesis (MES) technology have garnered considerable attention for their potential in sustainable protein production. This investigation focused on enriching HOB compatible with electrochemical systems through H₂-mediated MES, utilizing ammonium as the nitrogen source. Following a 65-day cultivation period in a sleeve-type bioreactor, taxonomic analysis revealed that Ancylobacter, identified as the predominant HOB genus, constituted 86.89 % of the microbial community. Furthermore, through optimization of current operational parameters, we achieved a significant enhancement in biomass productivity of autotrophic HOB. The biomass yield reached 121 ± 1 mg/L/day, representing a 46 % increase compared to the initial enrichment rate. The protein content was quantified at 64 ± 2 %, demonstrating parity with bacterial and fish meal proteins, while substantially exceeding that of soybean meal.