Sphingobacterium puteale sp. nov., isolated from a deep subsurface aquifer.

Abstract

A bacterial strain M05W1-28T was isolated from a well that collected water for irrigation from a deep aquifer at a depth of 400 m. Cells were observed to be rod-shaped, non-motile, aerobic, stained Gram-negative. Optimal growth was obtained at pH 7.0 (range: 6.0-9.0), 28 °C (range: 15-37 °C) and 0 % NaCl (range: 0-1.5 %, w/v) in modified tryptic soy broth (mTSB) without added NaCl and R2A. The cells were found to be positive for catalase and oxidase activities. The major fatty acids (>10 %) were identified as summed feature 3 (C16 : 1 ω7c / C16 : 1 ω6c) and iso-C15 : 0. The major polar lipids were phosphatidylethanolamine, glycolipid, phosphoglycolipids, phospholipids, and unidentified lipids. The major respiratory quinone was menaquinone-7 (MK-7). The genomic G+C content of strain M05W1-28T was 40.7 %. Based on similarities of 16S rRNA gene sequences, strain M05W1-28T was affiliated with the genus Sphingobacterium, exhibiting the highest sequence similarities with S. multivorum LMG 8342T (97.5 %), S. ginsenosidimutans THG07T (97.1 %) and less than 97.0 % to other members of the genus. The average nucleotide identity (ANI) and digital DNA-DNA hybridisation values (dDDH) between M05W1-28T and S. multivorum LMG 8342T were 78.1 and 22.5 %, respectively. Phenotypic characteristics including enzyme activities and carbon source utilisation differentiated the strain from other Sphingobacterium species. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain M05W1-28T represented a novel species within the genus Sphingobacterium, for which the name Sphingobacterium puteale sp. nov. is proposed. The type strain is M05W1-28T (=CGMCC 1.13711T=KCTC 72027T).