An iron corrosion-assisted H2-supplying system: a culture method for methanogens and acetogens under low H2 pressures

• Published in: Scientific reports Vol. 10; no. 1; p. 19124
• Main Authors: Kato, Souichiro, Takashino, Motoko, Igarashi, Kensuke, Mochimaru, Hanako, Mayumi, Daisuke, Tamaki, Hideyuki
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05.11.2020; Nature Publishing Group
• Subjects: 631/1647/2234; 631/326/171; 631/326/26/2527; Anaerobic environments; Anaerobic microorganisms; Corrosion; Enrichment media; Fermentation; Humanities and Social Sciences; Iron; Methanogenic bacteria; Microorganisms; multidisciplinary; Rice fields; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-76267-z

H 2 is an important fermentation intermediate in anaerobic environments. Although H 2 occurs at very low partial pressures in the environments, the culture and isolation of H 2 -utilizing microorganisms is usually carried out under very high H 2 pressures, which might have hampered the discovery and understanding of microorganisms adapting to low H 2 environments. Here we constructed a culture system designated the “iron corrosion-assisted H 2 -supplying (iCH) system” by connecting the gas phases of two vials (one for the iron corrosion reaction and the other for culturing microorganisms) to achieve cultures of microorganisms under low H 2 pressures. We conducted enrichment cultures for methanogens and acetogens using rice paddy field soil as the microbial source. In the enrichment culture of methanogens under canonical high H 2 pressures, only Methanobacterium spp. were enriched. By contrast, Methanocella spp. and Methanoculleus spp., methanogens adapting to low H 2 pressures, were specifically enriched in the iCH cultures. We also observed selective enrichment of acetogen species by the iCH system ( Acetobacterium spp. and Sporomusa spp.), whereas Clostridium spp. predominated in the high H 2 cultures. These results demonstrate that the iCH system facilitates culture of anaerobic microorganisms under low H 2 pressures, which will enable the selective culture of microorganisms adapting to low H 2 environments.