Paracoccus onchidii sp. nov., a moderately halophilic bacterium isolated from a marine invertebrate from the South China Sea.

Abstract

A novel moderately halophilic bacterial strain, designated Z330T, was isolated from the egg of a marine invertebrate of the genus Onchidium collected in the South China Sea. The 16S rRNA gene sequence of strain Z330T exhibited the highest similarity value to that of the type strain Paracoccus fistulariae KCTC 22803T (97.6%), Paracoccus seriniphilus NBRC 100798T (97.6%) and Paracoccus aestuarii DSM 19484T (97.6%). Phylogenomic and 16S rRNA phylogenetic analysis showed that strain Z330T was most closely related to P. seriniphilus NBRC 100798T and P. fistulariae KCTC 22803T. Strain Z330T grew optimally at 28-30°C, pH 7.0-8.0 with the presence of 5.0-7.0% (w/v) NaCl. In addition, growth of strain Z330T occurred at 0.5-16% NaCl, indicated strain Z330T was a moderately halophilic and halotolerant bacterium of genus Paracoccus. The predominant respiratory quinone in strain Z330T was identified as ubiquinone-10. The major polar lipids of strain Z330T were phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, glycolipid and six unidentified polar lipids. The major fatty acids of strain Z330T was summed feature 8 (C18:1 ω6c and/or C18:1 ω7c). The draft genome sequence of strain Z330T includes 4,084,570bp in total (N50 = 174,985bp) with a medium read coverage of 463.6 × and 83 scaffolds. The DNA G + C content of strain Z330T was 60.5%. In silico DNA-DNA hybridization with the four type strains showed 20.5, 22.3, 20.1 and 20.1% relatedness to Paracoccus fistulariae KCTC 22803T, Paracoccus seriniphilus NBRC 100798T, Paracoccus aestuarii DSM 19484T and Paracoccus denitrificans 1A10901T, respectively. And the average nucleotide identity (ANIb) values between strain Z330T and these four type strains were 76.2, 80.0, 75.8 and 73.8%, respectively, lower than the 95-96% threshold value for dividing prokaryotic species. On the basis of the phenotypic, phylogenetic, phylogenomic and chemotaxonomic properties, a novel species of the genus Paracoccus, Paracoccus onchidii sp. nov. is proposed with the type strain Z330T (= KCTC 92727T = MCCC 1K08325T).