Metagenomic and thermodynamic mapping of Ny-Ålesund, Arctic microbiota: harnessing low temperature biohydrogen...

Biohydrogen produced by psychrophilic dark fermentation has lower energy requirements than conventional methods. In this study, kinetic, thermodynamic, and functional metagenomic analyses were conducted to determine the profiles of microbial consortia from Ny-Ålesund, Svalbard, incubated at 4°C and 20°C in the presence or absence of the methanogenic inhibitor 2-bromoethanesulfonate. Biogas potential values derived from volumetric analyses indicated that pure biohydrogen (>95.6%) was produced, while also confirming the presence of these consortia adapted to operate with lag phases of 4-7 days and exhibiting temperature sensitivity coefficients (Q₁₀) <2.0 at 4°C. While thermodynamic analysis indicated that methanogenic inhibition theoretically disrupted syntrophic electron transfer and yielded a higher activation energy, both anaerobically fermentative acetic and butyric acid pathways remained exergonic. Community succession was observed in functional metagenomic analyses, marked by the enrichment of fermentative genera (Clostridium, Enterobacter, and Klebsiella) harboring the genetic potential for the pyruvate:ferredoxin oxidoreductase (PFOR) and formate hydrogenlyase (FHL) pathways. Metagenomic enrichment for the genes encoding cold-shock defense (cspA, dnaK) and putative electron-bifurcating complexes (rnf, ech) highlights the combined genetic potential to sustain viability and overcome thermodynamic limits at all incubation temperatures. Overall, the biochemical characteristics of native Arctic consortia provide evidence of their potential to serve as viable biocatalysts for biohydrogen production, currently under laboratory batch conditions at low temperatures.IMPORTANCEBiohydrogen production is a potentially sustainable energy source that offers new options for generating carbon-neutral renewable energy. Traditionally, biohydrogen production methods require substantial, continuous heating energy input. This publication describes the examination of the "underutilized" biohydrogen production potential of microbial communities in the Arctic region (Ny-Ålesund, Svalbard) that have separately evolved genetic adaptations necessary to maintain metabolic functions at sub-zero temperatures. Psychrophilic dark-fermentation experiments, combined with thermodynamic modeling and metagenomic analyses, show how unique cold-adapted microorganisms can produce high-purity biohydrogen gas at extreme ambient temperatures under laboratory batch conditions, highlighting a fundamental baseline that could inform future efforts to reduce the energy footprint of biofuel production. While long-term reactor stability and scalability remain to be validated, this work bridges the divide between observational Arctic microbiology and foundational green energy research, demonstrating that the discovery of extreme microbial environments holds promise for developing low-energy biological processes.