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

摘要

A bacterial strain utilizing methanol as the sole source of carbon and energy was isolated from the maize phy1-losphere. Cells are nonpigmented gram-negative motile rods that do not form spores or prosthecae and reproduce by binary fission. The strain does not require vitamins or supplementary growth factors. It is obligately aerobic and urease-, oxidase-, and catalase-positive. THe optimum growth temperature is 35-40 deg C; the optimum pH is 7.0-7.5. The doubling time is 2 h. The bacterium implements the ribulose monophosphate pathway and possesses NAD~+-dependent 6-phosphogluconate dehydrogenate nd enzymes of the glutamate cycle. #alpha#- Ketoglutarate dehydrogenase and enzymes of the glyoxylate cycle (isocitrate lyase and malate synthase) are absent. Fatty acids are dominated by apalmitic (C_16:0) and palmitoleic (C_16:1) acids. The major phospholipids are phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylcholine. Cardiolipin is present in minor amounts. 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 desaturation temperature (T_m). The G+C content of DNA is 57.2 mol %, as determined from the DNA thermal desaturation temperature (T_m). The bacterium shows low DNA homology (<10%) with restricted facultative methylotrophic bacteria of the genus Methylophilus (M.methylotrophus NCIMB 10515~t and M. leisingerii VKM B-2013~t) and whit the obligate methylotrophic bacterium (Methylobacillus glycogenes ATCCC 29475~t). DNA homology with the type representative of the genus Methylovorus, M. glucosetrophus VKM B-1745~t, is high (58%). The new isolate was classified as a new species, Methylovorus mays sp. now.