Emendation of Methylobacterium Patt, Cole, and Hanson 1976; Methylobacterium rhodinum (Heumann 1962) comb. nov. corrig.; Methylobacterium radiotolerans (Ito and Iizuka 1971) comb. nov. corrig.; and Methylobacterium mesophilicum (Austin and Goodfellow 1979) comb. nov.

The present definition of the genus Methylobacterium excludes organisms which do not utilize methane facultatively. However, reports have indicated that cultures of the type strain of the type species, Methylobacterium organophilum, can lose this feature easily. Furthermore, studies have shown that M. organophilum is phenotypically highly similar to the methane-nonutilizing, pink-pigmented, facultatively methylotrophic bacteria and that the latter should be excluded from the various genera to which they have been assigned previously. Therefore, in accordance with an earlier suggestion, we propose that the description of the genus Methylobacterium be emended to permit the inclusion of methane-nonutilizing organisms which are otherwise highly similar to the type species. We further propose that all of the pink-pigmented, facultatively methylotrophic bacteria, which include the species Pseudomonas rhodos, Pseudomonas radiora, and Pseudomonas mesophilica, be transferred to the genus Methylobacterium.