Flavobacterium magnesitis sp. nov. and Flavobacterium zubiriense sp. nov., two novel Flavobacterium species isolated from alkaline magnesite residues.

Abstract

Three bacterial strains, designated FZUC8N2.13^T, FBOR7N2.3^T and FZUR7N2.5, were isolated from distinct magnesite residues in Spain. Phylogenetic and phylogenomic analysis places them within the genus Flavobacterium. Strains FBOR7N2.3^T and FZUR7N2.5 share 100% of similarity in the 16S rRNA gene sequence, and both are most closely related to Flavobacterium cellulosilyticum AR-3-4^T with which they share 97.5% of 16S rRNA gene similarity. Strain FZUC8N2.13^T forms a distinct lineage most closely related to Flavobacterium lacustre IMCC36792^T with 97.7% 16S rRNA gene similarity. The closest phylogenomic neighbours of these three strains are Flavobacterium flevense DSM 1076^T, 'Flavobacterium undicola' BBQ-18^T and Flavobacterium commune PK15^T. The average nucleotide identity and digital DNA-DNA hybridization values between the three strains and closest members of the genus Flavobacterium are below the threshold values of 95% and 70%, respectively. Strains FZUC8N2.13^T, FBOR7N2.3^T and FZUR7N2.5 stain Gram-negative, are rod-shaped and form yellow colonies. Optimum growth occurs at 25 °C and pH 7. The genomic G+C contents are 33.4 mol% for strain FZUC8N2.13^T and 33.2 mol% for strains FBOR7N2.3^T and FZUR7N2.5. The major isoprenoid quinone is menaquinone 6. The major fatty acids are summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) (22.6-31.1%), iso-C_15 : 0 (13.6-16.2 %) and anteiso-C_15 : 0 (8.7-10.5%). The polar lipids consist of two aminolipids, two aminophospholipids and one glycolipid. The phylogenetic, phylogenomic, phenotypic and chemotaxonomic data indicate that FZUC8N2.13^T, FBOR7N2.3^T and FZUR7N2.5 are distinct from the described species of Flavobacterium and should be classified as novel species, for which we propose the names Flavobacterium zubiriense for strain FZUC8N2.13^T (=UCCCB 179^T=CECT 30977^T) and Flavobacterium magnesitis for strains FBOR7N2.3^T (=UCCCB 178^T=CECT 30976^T) and FZUR7N2.5 (=UCCCB 216=CECT 31036).