Chelativorans multitrophicus gen. nov., sp. nov. and Chelativorans oligotrophicus sp. nov., aerobic EDTA-degrading bacteria

Abstract

Two previously isolated strains (DSM 9103Tand LPM-4T) able to grow with EDTA (facultatively and obligately, respectively) as the source of carbon, nitrogen and energy were investigated in order to clarify their taxonomic positions. The strains were strictly aerobic, Gram-negative, asporogenous and non-motile rods that required biotin for growth. Reproduction occurred by binary fission. The strains were mesophilic and neutrophilic. Their major fatty acids were summed feature 7 (consisting of C18 : 1ω7c, C18 : 1ω9tand/or C18 : 1ω12t) and C19 : 0cycloω8c. The polyamine pattern revealed homospermidine as a major polyamine. Predominant polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylmonomethylethanolamine and diphosphatidylglycerol.Mesorhizobium-specific ornithine lipid was absent. The predominant isoprenoid quinone was Q-10. The DNA G+C values were 60.8 and 63.1 mol% (Tm) for strains LPM-4Tand DSM 9103T, respectively. The level of 16S rRNA gene sequence similarity between these EDTA-utilizers was 99.3 % while the DNA–DNA hybridization value was only 37 %. Both strains were phylogenetically related to members of the generaAminobacterandMesorhizobium(95–97 % sequence similarity). However, DNA–DNA hybridization values between the novel EDTA-degrading strains andAminobacter aminovoransDSM 7048TandMesorhizobium lotiDSM 2626Twere low (10–11 %). Based on their genomic and phenotypic properties, the new alphaproteobacterial strains are assigned to a novel genus,Chelativoransgen. nov., with the namesChelativorans multitrophicussp. nov. (type strain DSM 9103T=VKM B-2394T) andChelativorans oligotrophicussp. nov. (type strain LPM-4T=VKM B-2395T=DSM 19276T).