Cupriavidus alkaliphilus sp. nov., a new species associated with agricultural plants that grow in alkaline soils.

A group of 20 bacterial strains was isolated from the rhizosphere of different agricultural plants growing in alkaline soils in the northeast of Mexico. The phylogenetic analysis of the 16S rRNA gene sequence from four strains showed that this novel group belonged to the Cupriavidus genus, with C. taiwanensis (∼98.9%) and C. necator (∼98.8%) as the closest species. However, DNA-DNA reassociation values were less than 20%. The novel group did not fix nitrogen and lacked nifH and nodA genes, unlike C. taiwanensis. Whole-cell protein patterns were highly similar among the 20 strains but different from the closest Cupriavidus species. BOX-PCR patterns were distinct among the 20 strains but also differed from other Cupriavidus type species. The major cellular fatty acids from strains ASC-732(T) and SLV-2362 were C(16:0), C(18:1) ω7c/12t/9t and C(16:1) ω7c and/or C(15:0) iso 2OH. The major polar lipids consisted of phosphatidylglycerol, cardiolipin, phosphatidylethanolamine, 2-hydroxylated-phosphatidylethanolamine and an unknown aminolipid. The DNA G+C content of strain ASC-732(T) was 66.8mol%. All 20 strains grew in the presence of 5-10mgmL(-1) arsenic, 1mgmL(-1) zinc, and 0.1mgmL(-1) copper. Consequently, the group of strains was considered to represent a novel species for which the name Cupriavidus alkaliphilus sp. nov. is proposed. The type strain is ASC-732(T) (=LMG 26294(T)=CIP 110330(T)).