Whole-genome sequencing of Paracoccus species isolated from the healthy human eye and description of Paracoccus shanxieyensis sp. nov

Currently, the genus Paracoccus comprises 76 recognized species. Members of Paracoccus are mostly isolated from environmental, animal, and plant sources. This report describes and proposes a novel species of Paracoccus isolated from clinical specimens of the human ocular surface. We isolated two aerobic, Gram-stain-negative, non-spore-forming, coccoid or short rod-shaped, and non-motile strains (designated DK398T and DK608) from conjunctival sac swabs of two healthy volunteers. The results showed that the strains grew best under the conditions of 28°C, pH 7.0, and 1.0 % (w/v) NaCl. Sequence analysis based on the 16S rRNA gene showed that strains DK398T and DK608 were members of Paracoccus, most similar to Paracoccus laeviglucosivorans 43PT (98.54 and 98.62 %), Paracoccus litorisediminis GHD-05T (98.34 and 98.41 %), and Paracoccus limmosus NB88T (98.21 and 98.29 %). Phenotypic analysis showed that DK398T and DK608 were positive for catalase and oxidase, negative for producing N-acetyl-β-glucosaminic acid, arginine dihydrolase, and β-glucuronidase but positive for leucine arylamidase. The predominant isoprenoid quinone was Q-10, and the major polar lipids included phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, and an unidentified glycolipid. The major fatty acids (>10%) were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and C16 : 0. The meso-diaminopimelic acid was found in the cell wall peptidoglycan of DK398T. The major cell wall sugars were ribose and galactose. Based on the results of phylogenetic analyses, low (<83.22 %) average nucleotide identity, digital DNA-DNA hybridization (<26.0%), chemotaxonomic analysis, and physiological properties, strain DK398T represents a novel species of the genus Paracoccus, for which the name Paracoccus shanxieyensis sp. nov. is proposed. The type strain is DK398T (=CGMCC 1.17227T=JCM 33719T).