Aquidulcibacter paucihalophilus gen. nov., sp. nov., a novel member of family Caulobacteraceae isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, TH1-2, was isolated from cyanobacterial aggregates in the eutrophic Lake Taihu, Jiangsu Province, China. Cells were observed to be Gram-negative, slightly curved and rod-shaped. Optimal growth was obtained at pH 7.0 (range 5.5-8.5) and 30 °C (range 20-37 °C) in trypticase soy broth (TSB) without NaCl. Growth was not observed in TSB with 1.0% (w/v) NaCl added. The cells were found to be positive for oxidase and catalase activities. The major fatty acids were identified as 3-hydroxy hexadecanoic acid (C 3-OH), C ω5c and summed feature 8 (consisting of C ω6c and cis-11-Octadecenoic acid (C ω7c). The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The 16S rRNA gene sequence of strain TH1-2 was found to be phylogenetically related to those of Glycocaulis abyssi MCS 33 and Brevundimonas naejangsanensis BIO-TAS2-2 (90.5 and 90.0% similarity, respectively). The genomic G+C content of strain TH1-2 was 55.6 mol% based on whole genome calculations. Average nucleotide identities (ANI) and the digital DNA-DNA hybridizations (DDH) for complete genomes ranged from 66.84  to 67.32  and 21.3 to 31.8% between strain TH1-2 and type strains within the family Caulobacteraceae, higher than those between strain TH1-2 and the strains within the family Hyphomonadaceae. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis, indicate that strain TH1-2 (=CGMCC 1.12979 = LMG 28362) represents a novel species in a new genus within the family Caulobacteraceae; thus, the name Aquidulcibacter paucihalophilus gen. nov., sp. nov., is proposed.