Halomonas avicenniae sp. nov., isolated from the salty leaves of the black mangrove Avicennia germinans in Puerto Rico

Abstract

A Gram-negative, short rod to oval-shaped bacterium (strain MW2aT) was isolated from the surface of leaves of the black mangrove Avicennia germinans and subjected to a polyphasic taxonomic study. Strain MW2aT was moderately halophilic, growing at NaCl concentrations in the range 0–25 % (w/v) with optimum growth at 5 % (w/v) NaCl. Growth occurred at 12–40 °C (optimum, 30–35 °C) and at pH 5.0–9.0 (optimum, pH 7.0–8.0). Strain MW2aT was strictly aerobic. Phylogenetic analysis based on the 16S rRNA gene showed that the strain belongs to the genus Halomonas. The closest relative was Halomonas marisflavi, with 98.6 % 16S rRNA gene sequence similarity. The DNA G+C content of strain MW2aT was 61.5 mol%, which is in the range of values for Halomonas species. DNA–DNA hybridization with H. marisflavi showed a relatedness of 42 % and lower values were obtained with respect to other related Halomonas species. The major fatty acids were C16 : 0, C19 : 0 cyclo ω8c, C18 : 1 ω7c and C12 : 0 3-OH. Overall, the phenotypic, genotypic and phylogenetic results presented in this study demonstrate that strain MW2aT represents a novel species within the genus Halomonas. The name Halomonas avicenniae sp. nov. is proposed, with strain MW2aT (=CECT 7193T=CCM 7396T) as the type strain.