Substrate-dependent transcriptomic shifts in Pelotomaculum thermopropionicum grown in syntrophic co-culture with Methanothermobacter thermautotrophicus.
Bottom Line: As it thrives on a very small energy conserved by propionate oxidation under syntrophic association with a methanogen, its catabolic pathways and regulatory mechanisms are of biological interest.Expression of the central catabolic pathway (the propionate-oxidizing methylmalonyl-CoA pathway) was found to be substrate-dependent and was largely stimulated when P. thermopropionicum was grown on propionate and lactate.These results revealed that P. thermopropionicum has complex regulatory mechanisms that alter its metabolism in response to the syntrophic partner and growth substrates.
Affiliation: Laboratory of Applied Microbiology, Marine Biotechnology Institute, Kamaishi, Iwate 026-0001, Japan.Show MeSH
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Mentions: Pelotomaculum thermopropionicum was grown in monoculture on fumarate or in co‐culture with Methanothermobacter thermautotrophicus on ethanol, 1‐propanol, lactate or propionate. Substrates degradation and products formation are shown in Fig. 1, and growth rates of P. thermopropionicum and M. thermautotrophicus are summarized in Table 1. As reported previously (Imachi et al., 2000; 2002), syntrophic propionate degradation was very slow; it took more than 40 days to utilize 20 mM propionate, and there was a long lag period before a detectable amount of methane was produced. In contrast, the other substrates were completely degraded within 3 days (Fig. 1). A specific growth rate of P. thermopropionicum in propionate culture was estimated to be less than one‐tenth of that in the monoculture on fumarate (Table 1).
Affiliation: Laboratory of Applied Microbiology, Marine Biotechnology Institute, Kamaishi, Iwate 026-0001, Japan.