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

Three bacterial strains, designated FZUC8N2.13T, FBOR7N2.3T and FZUR7N2.5, were isolated from distinct magnesite residues in Spain. Phylogenetic and phylogenomic analysis places them within the genus Flavobacterium. Strains FBOR7N2.3T and FZUR7N2.5 share 100% of similarity in the 16S rRNA gene sequence, and both are most closely related to Flavobacterium cellulosilyticum AR-3-4T with which they share 97.5% of 16S rRNA gene similarity. Strain FZUC8N2.13T forms a distinct lineage most closely related to Flavobacterium lacustre IMCC36792T with 97.7% 16S rRNA gene similarity. The closest phylogenomic neighbours of these three strains are Flavobacterium flevense DSM 1076T, ‘Flavobacterium undicola’ BBQ-18T and Flavobacterium commune PK15T. 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 FZUC8N2.13T, FBOR7N2.3T 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 FZUC8N2.13T and 33.2 mol% for strains FBOR7N2.3T and FZUR7N2.5. The major isoprenoid quinone is menaquinone 6. The major fatty acids are summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) (22.6–31.1%), iso-C15 : 0 (13.6–16.2 %) and anteiso-C15 : 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 FZUC8N2.13T, FBOR7N2.3T 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 FZUC8N2.13T (=UCCCB 179T=CECT 30977T) and Flavobacterium magnesitis for strains FBOR7N2.3T (=UCCCB 178T=CECT 30976T) and FZUR7N2.5 (=UCCCB 216=CECT 31036).