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

Int J Syst Evol Microbiol. 2023 Apr;73(4). doi: 10.1099/ijsem.0.005838.


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).

Keywords: Paracoccus; healthy human eye; novel species; phylogenetic analysis; sequence analysis; whole-genome sequencing.

MeSH terms

  • Animals
  • Bacterial Typing Techniques
  • Base Composition
  • DNA, Bacterial / genetics
  • Fatty Acids* / chemistry
  • Humans
  • Paracoccus*
  • Phospholipids / chemistry
  • Phylogeny
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Ubiquinone / chemistry


  • Fatty Acids
  • Phospholipids
  • RNA, Ribosomal, 16S
  • Ubiquinone
  • DNA, Bacterial