Citricoccus zhacaiensis sp. nov., isolated from a bioreactor for saline wastewater treatment

A Gram-positive, neutrophilic, non-motile and non-spore-forming actinobacterium, strain FS24T, was isolated from a bioreactor treating salt-containing wastewater. This isolate grew in the presence of 0–15 % (w/v) NaCl and at 10-37 °C. The optimum NaCl concentration for growth of FS24T was 5 % (w/v) at 37 °C or 1 % (w/v) at 25 °C. Chemotaxonomic analysis revealed MK-9(H2) as the predominant menaquinone and the major cellular polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, four unknown glycolipids, two unknown phospholipids and an unknown lipid. The major fatty acids were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The genomic DNA G+C content was 66.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain FS24T clustered with members of the genus Citricoccus, exhibiting high sequence similarity to the 16S rRNA gene sequences of the type strains of Citricoccus alkalitolerans (98.9 %) and Citricoccus muralis (98.8 %), respectively. The DNA–DNA relatedness values of strain FS24T to C. alkalitolerans DSM 15665T and C. muralis DSM 14442T were 54 and 39 %, respectively. On the basis of phenotypic and genotypic data, strain FS24T represents a novel species of the genus Citricoccus, for which the name Citricoccus zhacaiensis sp. nov. is proposed. The type strain is FS24T (=CGMCC 1.7064T =JCM 15136T).