Verticiella alkaliphila  sp. nov., An Alkaliphilic, Arsenic-Resistant Bacterium Isolated from the Gut of Lepidocephalichthys guntea

Detailed phenotypic and genotypic characterization was done to establish the taxonomic position of a novel bacterial strain GG226^T, frequently been isolated from the gut of Lepidocephalichthys guntea. Strain GG226^T a Gram-negative, facultatively anaerobic, rod-shaped, motile, alkaliphilic bacterium. The 16S rRNA gene sequences analysis disclosed that GG226^T belongs to genus Verticiella due to its maximum sequence identity with Verticiella sediminum XH089^T (98.4%), the sole representative of this genus. A genome BLAST distance phylogeny (GBDP) tree, single nucleotide polymorphism (SNP) tree, and multi locus species tree (MLST) reconfirmed that GG226^T shares its closest taxonomic identity with Verticiella sediminum XH089^T. The DNA G + C content was estimated to be 67 mol%. When compared with Verticiella sediminum XH089^T the DNA-DNA hybridization (dDDH) value was 21.90% and the average nucleotide identity (ANI) value was 80.13%; both of which were sufficiently below the threshold value (≤ 70% and ≤ 95–96%) for new prokaryotic species validation. The dominant fatty acids (> 5% of total fatty acids) were C_16:0, summed feature 3 (C_16:1ω7c/C_16:1ω6c), C_17:0 cyclo, and C_12:0 3-OH. The strain GG226^T has shown significant growth in pH 9 and 10, and noticeable high resistance to sodium arsenate (MIC: > 500 mM). The results of biochemical tests, phenotypic characteristics, genotypic data, and physiological properties could differentiate strain GG226^T from its closest taxonomic relative. Hence, characterization based on chemotaxonomic, phenotypic, genomic, and phylogenetic evidence demonstrated that the strain GG226^T represents a novel species of the genus Verticiella, for which the name Verticiella alkaliphila sp. nov. (type strain GG226^T = MCC 5181^T = JCM 36073^T) is proposed.