Leisingera coralii sp. nov., a bacterium isolated from seawater surrounding Acropora digitata.

Abstract

Coral reefs are experiencing significant degradation, largely driven by rising seawater temperatures. The bacterial communities within coral holobionts play crucial roles that support coral reef conservation and restoration, offering potential solutions to mitigate the impacts of environmental stressors. A Gram-negative bacterium, designated strain D0M16^T, was isolated from seawater surrounding Acropora digitata coral in Daya Bay, Shenzhen, Guangdong Province, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed the closest relatives to be Cribrihabitans neustonicus JCM 19537^T (97.40%) and Leisingera thetidis KCTC 92110^T (97.04%). Phylogenomic analysis showed that the strain D0M16^T represents a novel species within the genus Leisingera. Cell growth occurred at 20-45 °C temperature, 0-9% (w/v) NaCl concentration and pH 6.0-8.0, with optimum conditions at 28-37 °C temperature, 1% (w/v) NaCl concentration and pH 7.0. Chemotaxonomic characterization identified summed feature 8 as the predominant fatty acid (67.6%), with ubiquinone-10 as the major respiratory quinone. The genome size was 4.77 Mb, with a DNA G+C content of 64.0 mol%. Comparative genomic analysis revealed that the average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between D0M16^T and L. thetidis KCTC 92110^T were 88.2%, 89.4% and 53.4%, respectively, and those values of 90.4%, 92.8% and 38.7% between D0M16^T and Leisingera caerulea DSM 24564^T, respectively. The phylogenomic tree further confirmed the distinct taxonomic position of D0M16^T relative to these closely related species. Based on comprehensive phylogenomic, phenotypic and chemotaxonomic characteristics, strain D0M16^T represents a novel species of the genus Leisingera, for which the name Leisingera coralii sp. nov. is proposed. The type strain is D0M16^T (=MCCC 1K09457^T=KCTC 18159^T).