Pseudoxanthobacter soli gen. nov., sp. nov., a nitrogen-fixing alphaproteobacterium isolated from soil

A Gram-type negative or variable, aerobic, rod-shaped, nitrogen-fixing bacterium, designated strain CC4(T), was isolated on nutrient agar from a soil sample collected at a regional agricultural research field station located in Kaohsiung County, Taiwan. 16S rRNA gene sequence analysis demonstrated that this isolate is unique, showing <92.5 % similarity with respect to species of the genera Xanthobacter (maximum of 92.2 % similarity), Prosthecomicrobium (92.0 %), Devosia (91.9 %), Kaistia (91.9 %) and Methylocystis (91.9 %). The organism utilized acetic acid, formic acid, beta-hydroxybutyric acid, dl-lactic acid, succinic acid, bromosuccinic acid, l-alaninamide, l-alanine, l-alanyl glycine, l-glutamic acid and l-proline as substrates, but not methanol or methylamine. Chemotaxonomic data revealed that strain CC4(T) contains ubiquinone Q-10 as the major respiratory quinone. The characteristic diamino acid of the peptidoglycan was meso-diaminopimelic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, an unknown lipid and an unknown aminolipid. The fatty acid profile differed from those of members of the genera Xanthobacter, Prosthecomicrobium, Devosia and Kaistia. The predominant fatty acids were C(18 : 1)omega7c, C(19 : 0) cyclo and C(16 : 0). On the basis of 16S rRNA gene sequence analysis in combination with chemotaxonomic and physiological data, strain CC4(T) represents a novel genus and species, for which we propose the name Pseudoxanthobacter soli gen. nov., sp. nov. The type strain of Pseudoxanthobacter soli is CC4(T) (=DSM 19599(T) =CIP 109513(T)).