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

A novel moderately halophilic bacterial strain, designated Z330 ^T , 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 Z330 ^T exhibited the highest similarity value to that of the type strain Paracoccus fistulariae KCTC 22803 ^T (97.6%), Paracoccus seriniphilus NBRC 100798 ^T (97.6%) and Paracoccus aestuarii DSM 19484 ^T (97.6%). Phylogenomic and 16S rRNA phylogenetic analysis showed that strain Z330 ^T was most closely related to P. seriniphilus NBRC 100798 ^T and P. fistulariae KCTC 22803 ^T . Strain Z330 ^T 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 Z330 ^T occurred at 0.5-16% NaCl, indicated strain Z330 ^T was a moderately halophilic and halotolerant bacterium of genus Paracoccus. The predominant respiratory quinone in strain Z330 ^T was identified as ubiquinone-10. The major polar lipids of strain Z330 ^T were phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, glycolipid and six unidentified polar lipids. The major fatty acids of strain Z330 ^T was summed feature 8 (C _18:1 ω6c and/or C _18:1 ω7c). The draft genome sequence of strain Z330 ^T includes 4,084,570 bp in total (N50 = 174,985 bp) with a medium read coverage of 463.6 × and 83 scaffolds. The DNA G + C content of strain Z330 ^T 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 22803 ^T , Paracoccus seriniphilus NBRC 100798 ^T , Paracoccus aestuarii DSM 19484 ^T and Paracoccus denitrificans 1A10901 ^T , respectively. And the average nucleotide identity (ANIb) values between strain Z330 ^T 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 Z330 ^T (= KCTC 92727 ^T  = MCCC 1K08325 ^T ).
(© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)