Description of Labrys sedimenti sp. nov., isolated from a diclofenac-degrading enrichment culture, and genome-based reclassification of Labrys portucalensis as a later heterotypic synonym of Labrys neptuniae

A Gram-stain-negative strain, designated as Zidic-5^T, was isolated from diclofenac-degrading enrichment culture and characterized using a polyphasic approach to determine its taxonomic position. The 16S rRNA gene sequence analysis revealed that strain Zidic-5^T belongs to the genus <i>Labrys</i>, with the highest 16S rRNA gene similarity to <i>Labrys neptuniae</i> LMG 23578^T (99.13%), followed by <i>Labrys portucalensis</i> F11^T (99.06%), <i>Labrys methylaminiphilus</i> JLW10^T (98.58%) and <i>Labrys okinawensis</i> DSM 18385^T (98.32%). The draft genome sequence of strain Zidic-5^T is 7.64 Mb long, and the G+C content of the genome is 63.5 mol%. The orthologous average nucleotide identity and digital DNA-DNA hybridization relatedness values between strain Zidic-5^T and its closest relatives were below the threshold values for species demarcation, confirming that strain Zidic-5^T is distinctly separated from its closest relatives. Additionally, comparative whole-genome analysis of type strains of <i>L. neptuniae</i> and <i>L. portucalensis</i> indicated that they belong to the same genomic species, suggesting that <i>L. portucalensis</i> is a later heterotypic synonym of <i>L. neptuniae</i>. Cells of strain Zidic-5^T were strictly aerobic, coccoid-shaped and non-motile. The predominant fatty acids (>10% of the total) of strain Zidic-5^T were C_{18 : 1} ω7c, C_{16 : 0} and C_{19 : 0} cyclo ω7c. The major ubiquinone of strain Zidic-5^T was Q-10, while the major polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and aminophospholipid. Based on the polyphasic study, it is concluded that strain Zidic-5^T represents a novel species of the genus <i>Labrys</i>; thus, the name of <i>Labrys sedimenti</i> sp. nov. is proposed. The type strain of the species is strain Zidic-5^T (=LMG 33565^T=NCAIM B.02686^T).