Methylovorus mays sp nov.: A new species of aerobic, obligately methylotrophic bacteria associated with plants

A bacterial strain utilizing methanol as the sole source of carbon and ener gy was isolated from the maize phyllosphere. Cells are nonpigmented gram-ne gative motile rods that do not form spores or prosthecae and reproduce by b inary fission. The strain does not require vitamins or supplementary growth factors. It is obligately aerobic and urease-, oxidase-, and catalase-posi tive. The optimum growth temperature is 35-40 degreesC; the optimum pH is 7 .0-7.5. The doubling time is 2 h. The bacterium implements the ribulose mon ophosphate pathway and possesses NAD(+)-dependent 6-phosphogluconate dehydr ogenase and enzymes of the glutamate cycle. a-Ketoglutarate dehydrogenase a nd enzymes of the glyoxylate cycle (isocitrate lyase and malate synthase) a re absent. Fatty acids are dominated by palmitic (C-16:0) and palmitoleic ( C-16:1) acids. The major phospholipids are phosphatidylethanolamine, phosph atidylglycerol, and phosphatidylcholine. Cardiolipin is present in minor am ounts. The dominant ubiquinone is Q(8). The bacterial genome contains genes controlling the synthesis and secretion of cytokinins. The G+C content of DNA is 57.2 mol %, as determined from the DNA thermal denaturation temperat ure (T-m). The bacterium shows low DNA homology (<10%) with restricted facu ltative methylotrophic bacteria of the genus Methylophilus (M. methylotroph us NCIMB 10515(T) and M. leisingerii VKM B-2013(T)) and with the obligate m ethylotrophic bacterium (Methylobacillus glycogenes ATCC 29475(T)). DNA hom ology with the type representative of the genus Methylovorus, M. glucosetro phus VKM B-1745(T) is high (58%). The new isolate was classified as a new s pecies, Methylovorus mays sp. nov.