Aerobic H 2 production related to formate metabolism in white-rot fungi.

Biohydrogen is mainly produced by anaerobic bacteria, anaerobic fungi, and algae under anaerobic conditions. In higher eukaryotes, it is thought that molecular hydrogen (H ₂ ) functions as a signaling molecule for physiological processes such as stress responses. Here, it is demonstrated that white-rot fungi produce H ₂ during wood decay. The white-rot fungus Trametes versicolor produces H ₂ from wood under aerobic conditions, and H ₂ production is completely suppressed under hypoxic conditions. Additionally, oxalate and formate supplementation of the wood culture increased the level of H ₂ evolution. RNA-seq analyses revealed that T. versicolor oxalate production from the TCA/glyoxylate cycle was down-regulated, and conversely, genes encoding oxalate and formate metabolism enzymes were up-regulated. Although the involvement in H ₂ production of a gene annotated as an iron hydrogenase was uncertain, the results of organic acid supplementation, gene expression, and self-recombination experiments strongly suggest that formate metabolism plays a role in the mechanism of H ₂ production by this fungus. It is expected that this novel finding of aerobic H ₂ production from wood biomass by a white-rot fungus will open new fields in biohydrogen research.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2023 Mori, Takahashi, Soga, Arimoto, Kishikawa, Yama, Dohra, Kawagishi and Hirai.)