Lanthanide-dependent Methanotroph Thrives on Radioactive Promethium

Promethium is the only Lanthanide (Ln) that exists exclusively as unstable isotopes, which consequently prevents its occurrence in appreciable amounts in nature. Lns have shown to be biologically relevant for methanotrophic and methylotrophic bacteria. This paper presents growth studies on the methanotrophic bacterium Methylacidiphilum fumariolicum SolV with Pm-147 along with enzymatic assays of its Ln-dependent methanol dehydrogenase. The results indicate that Pm is positioned precisely as assumed within the Ln series in a biological context, despite its radioactivity.