Alteromonas fortis sp. nov., a non-flagellated bacterium specialized in the degradation of iota-carrageenan, and emended description of the genus Alteromonas

Tristan Barbeyron (1) , Erwann Zonta (1) , Sophie Le Panse (2, 3) , Éric Duchaud (4) , Gurvan Michel (1)

1 LBI2M - Laboratoire de Biologie Intégrative des Modèles Marins
2 SBR - Station biologique de Roscoff [Roscoff]
3 FR2424 - Fédération de recherche de Roscoff
4 VIM (UR 0892) - Unité de recherche Virologie et Immunologie Moléculaires

Strain 1T, isolated in the seventies from the thallus of the carrageenophytic red algae Eucheumaspinosum collected in Hawaii, USA, was retrospectively characterized using phenotypic,phylogenetic and genomic methods. Bacterial cells were Gram-stain-negative, strictly aerobic,non-flagellated, coccoid, ovoid or rod-shaped, and grew at 10-42 °C (optimum 20-25 °C), atpH 5.5-10 (optimum pH 6-9) and with 2-12 % NaCl (optimum 2-4 %). Strain 1T grew on theseaweed polysaccharides i-carrageenan, laminarin and alginic acid as sole carbon sources. Themajor fatty acids (>10 %) were C16:0, C18:1 ω7c and summed feature 3 (C16:1w7c and/or iso-C15:02OH) and significant amounts of C16:0 N alcohol (6.7 %) and 10 methyl C17:0 (8.6 %) were alsopresent. The only respiratory quinone was Q-8, and major polar lipids werephosphatidylethanolamine, phosphatidylglycerol and an unknown aminolipid. Phylogeneticanalyses based on 16S rRNA gene sequence comparisons showed that the bacterium is affiliatedto the genus Alteromonas (family Alteromonadaceae, class Gammaproteobacteria). Strain 1Texhibits 16S rRNA gene sequence similarity values of 98.8-99.2 % to the type strains ofAlteromonas mediterranea and Alteromonas australica respectively, and of 95.7-98.6 % tothose of the other species of the genus Alteromonas. The DNA G+C content of strain 1T is 43.9mol%. Based on the genome sequence of strain 1T, DNA-DNA hybridization predictions by theaverage nucleotide identity (ANI) and Genome-to-Genome Distance Calculations (GGDC)between strain 1T and other members of the genus Alteromonas showed values of 70-80 %, andbelow 26 %, respectively. The phenotypic, phylogenetic and genomic analyses show that strain 1T is distinct from species of the genus Alteromonas with validly published names and that itrepresents a novel species of the genus Alteromonas, for which the name Alteromonas fortis sp.nov. is proposed. The type strain is 1T (= ATCC 43554T = CIP XXXX).

Mots clés: Alteromonas fortis; Alteromonadaceae; iota-carrageenase; average nucleotide identity; dDDH; digital DNA-DNA hybridization; GGDC

Domaines: Bactériologie

Tristan Barbeyron, Erwann Zonta, Sophie Le Panse, Éric Duchaud, Gurvan Michel. Alteromonas fortis sp. nov., a non-flagellated bacterium specialized in the degradation of iota-carrageenan, and emended description of the genus Alteromonas. International Journal of Systematic and Evolutionary Microbiology, 2019, 69 (8), pp.2514-2521. ⟨10.1099/ijsem.0.003533⟩. ⟨hal-02353973⟩