Electron acceptor availability alters carbon and energy metabolism in a thermoacidophile

Abstract

The thermoacidophilic Acidianus strain DS80 displays versatility in its energy metabolism and can grow autotrophically and heterotrophically with elemental sulfur (S°), ferric iron (Fe ) or oxygen (O ) as electron acceptors. Here, we show that autotrophic and heterotrophic growth with S° as the electron acceptor is obligately dependent on hydrogen (H ) as electron donor; organic substrates such as acetate can only serve as a carbon source. In contrast, organic substrates such as acetate can serve as electron donor and carbon source for Fe or O grown cells. During growth on S° or Fe with H as an electron donor, the amount of CO assimilated into biomass decreased when cultures were provided with acetate. The addition of CO to cultures decreased the amount of acetate mineralized and assimilated and increased cell production in H /Fe grown cells but had no effect on H /S° grown cells. In acetate/Fe grown cells, the presence of H decreased the amount of acetate mineralized as CO in cultures compared to those without H . These results indicate that electron acceptor availability constrains the variety of carbon sources used by this strain. Addition of H to cultures overcomes this limitation and alters heterotrophic metabolism.

Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs

“…This transfer protocol was conducted a second time, and DNA was extracted from the final transferred enrichments following 3-week incubation using a modified phenol-chloroform extraction as previously described (Amenabar, Colman, Poudel, Roden, & Boyd, 2018).…”

“…Cultures were incubated for 3 weeks, and growth was monitored via cell counting as described above. This transfer protocol was conducted a second time, and DNA was extracted from the final transferred enrichments following 3‐week incubation using a modified phenol–chloroform extraction as previously described (Amenabar, Colman, Poudel, Roden, & Boyd, ). PCR amplicons for bacterial or archaeal‐specific 16S rRNA genes were generated and sequenced using the same protocols for the sediment SSU cDNA amplicons as described above.…”

Probing the geological source and biological fate of hydrogen in Yellowstone hot springs

“…A). If this Hyd is involved in H 2 oxidation, this finding may suggest that Caldisericum is supplementing organotrophic S 0 dependent growth with electrons from H 2 in a manner similar to that described for several other thermophilic S 0 reducers when grown organotrophically (Jochimsen et al ., ; Amenabar et al ., ). Of the hydrogenase transcripts detected, the majority were attributed to expression of homologues of [NiFe]‐hydrogenases predicted to be involved in H 2 oxidation (Fig.…”

Editorial: Microbial Hydrogen Metabolism

“…In many organisms, the ability to metabolize H 2 is a facultative trait that is regulated through the expression and maturation of hydrogenases (Schwartz et al, 2013;. In such taxa, H 2 represents a substrate that organisms utilize to supplement their energy metabolism, thereby allowing for an expansion of their niche space in ecosystems where other sources of reductant are low or variable in supply (e.g., Amenabar et al, 2018).…”