Alterisphingorhabdus coralli gen. nov. sp. nov., a novel aerobic anoxygenic phototrophic bacteria isolated from reef-building coral

The photosynthetic microorganisms within the coral holobiont produce energy and organic compounds through photosynthesis, which are vital for the biocalcification and heat tolerance of coral hosts. However, aerobic anoxygenic phototrophic bacteria (AAPB), which are one of the most important photosynthetic microorganisms, have not been thoroughly investigated in this environment. In this study, a novel AAPB, SCSIO 66989^T, was isolated from the reef-building coral <i>Favia</i> sp. and considered a beneficial microorganism for corals (BMC). The polyphasic taxonomic analysis showed that it had the highest similarities with <i>Parasphingorhabdus litoris</i> DSM 22379^T (95.9%) and <i>Altererythrobacter ishigakiensis</i> ATCC BAA-2084^T (95.7%). Phylogenetic analysis showed that it formed an independent clade, distinguishing it from other genera within the family <i>Sphingomonadaceae</i>. The predominant fatty acids were C_{18 : 1} <i> ω7</i>c and/or C_{18 : 1} <i> ω6</i>c and C_{16 : 0}. The major respiratory quinone was ubiquinone-10 (Q-10). Sphingolipid, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine were the diagnostic polar lipids. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between SCSIO 66989^T and the type strains of <i>P. litoris</i> DSM 22379^T and <i>A. ishigakiensis</i> ATCC BAA-2084^T were 69.2-70.0%, 58.6-61.2% and 19.2-19.7%, respectively. These results indicate that strain SCSIO 66989^T represents a new species of a novel genus in the family <i>Sphingomonadaceae</i>, for which the name <i>Alterisphingorhabdus coralli</i> gen. nov. sp. nov. is proposed.