Methylobacillus caricis sp. nov., an obligate methylotroph isolated from roots of sedge (Carex sp.)

Abstract

A new obligately methylotrophic bacterium, strain OVT, was isolated from roots of sedge (Carex sp.). The isolate was represented by aerobic gram-negative motile, non-spore-forming rods, which divided by binary fission. Optimal growth occurred at 22−29°C and pH 7.5−8.5 in the presence of 0.5−2% NaCl; growth was inhibited by 3.5% NaCl. Strain OVT utilized methanol as the only carbon and energy source. The organism used the KDPG variant of the ribulose monophosphate pathway (RuMP) of С1 metabolism. Ammonium was assimilated by reductive amination of α-ketoglutarate. The major cellular fatty acids were C16:0 (45.5%), C16:1ω7c (40.7%), and C17cyc (8.0%). The major ubiquinone was Q8. The dominant phospholipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The DNA G + C content of strain OVT was 51.4 mol % (Tm). While the 16S rRNA gene sequence of strain OVT exhibited high similarity to those of Methylobacillus species: M. gramineus LapT (99.6%) and M. glycogenes TK 0113T (98.7%), the DNA-DNA hybridization level between strain OVT and M. gramineus LapT was only 52%. Based on the data obtained, strain OVT was assigned to the new species Methylobacillus caricis sp. nov. (=VKM B-3158T = JCM 32031T).