Muricauda onchidii sp. nov., isolated from a marine invertebrate from South China Sea, and transfers of Flagellimonas algicola, Flagellimonas pacifica and Flagellimonas maritima to Muricauda algicola comb. nov., Muricauda parva nom. nov. and Muricauda aurantiaca nom. nov., respectively, and emended description of the genus Muricauda

Abstract

An aerobic, Gram-stain-negative, rod-shaped and non-motile strain (XY-359^T) was isolated from the mouth of a marine invertebrate <i>Onchidium</i> species from the South China Sea. It grew at pH 6.0-8.5 (optimum, pH 7.5), at 15-37 °C (optimum, 30 °C) and in the presence of 0.5-4.5 % (w/v) NaCl (optimum, 2.5 %). It could not hydrolyse Tweens 20, 40, 60 or 80 and no flexirubin-type pigments were produced. The major polar lipids were phosphatidylethanolamine, one unidentified aminolipid, six unidentified phospholipids and two unidentified polar lipids. The major fatty acids were iso-C_17:0 3-OH, iso-C_15:1 G and iso-C_15:0 3-OH. The respiratory quinone was MK-6. Strain XY-359^T showed the greatest degree of 16S rRNA sequence similarity to <i>Flagellimonas algicola</i> AsT0115^T (96.54 %), followed by <i>Muricauda flava</i> DSM 22638^T (96.27 %). Phylogenetic analysis based on 16S rRNA gene sequences and 31 core genes indicated that strain XY-359^T belongs to the genus <i>Muricauda</i>. The genome size of strain XY-359^T was 4 207 872 bp, with 39.1 mol% of DNA G+C content. The average nucleotide identity and digital DNA-DNA hybridization values between strain XY-359^T and <i>F. algicola</i> AsT0115^T were 74.58 % and 18.5 %, respectively, and those between strain XY-359^T and <i>M. flava</i> DSM 22638^T were 74.2 % and 18.3 %. The combined phenotypic, chemotaxonomic and phylogenetic data suggest that strain XY-359^T represents a novel species of the genus <i>Muricauda</i>, for which the name <i>Muricauda onchidii</i> sp. nov. is proposed. The type strain is XY-359^T (=MCCC 1K03658^T =KCTC 72218^T). Moreover, based on the proposal of nesting <i>Spongiibacterium</i> and <i>Flagellimonas</i> within <i>Muricauda</i> by García (Validation List No. 193) and the analyses of phylogenetic trees and average amino acid identities in this study, the transfers of <i>F. algicola</i>, <i>F. pacifica</i> and <i>F. maritima</i> to the genus <i>Muricauda</i> as <i>Muricauda algicola</i> comb. nov., <i>Muricauda parva</i> nom. nov. and <i>M. aurantiaca</i> nom. nov., respectively, are proposed, with an emended description of the genus <i>Muricauda</i>.