Pontibacterium sinense sp. nov., a nitrate-reducing and thiosulphate-oxidizing bacterium, isolated from coastal sediment

Abstract

A novel bacterial strain, N1Y112T, was isolated from coastal sediment collected in Weihai, PR China. This Gram-stain-negative, facultatively anaerobic, motile rod-shaped bacterium exhibited the ability to oxidize thiosulphate to sulphate and reduce nitrate to ammonia through its Sox system and nitrate reduction pathway, respectively. The strain grew at 20–35 °C (optimum, 28 °C), pH 6.0–10.0 (optimum, pH 7.5) and in the presence of 1.0–5.0 % (w/v) NaCl (optimum, 3.0 %). Major fatty acids present in the strain included summed feature 8 (comprising C18 : 1  ω7c and/or C18 : 1  ω6c), summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c) and C16 : 0. Its polar lipid profile consisted of one phosphatidylethanolamine, two unknown aminolipids, one aminophosphoglycolipid, one diphosphatidylglycerol, one phosphatidylglycerol, two unknown phospholipids and two unknown lipids. Strain N1Y112T contained ubiquinone-7 and ubiquinone-8 as isoprenoid quinones, with a genomic G+C content of 50.6 mol%. Based on phylogenetic analysis, strain N1Y112T clustered with Pontibacterium granulatum JCM 30316T being its closest relative at 97.1 % 16S rRNA gene sequence similarity. The average nucleotide identity and digital DNA–DNA hybridization values were 77.1 and 20.7 %, respectively, which suggest significant differences between genomes of N1Y112T and P. granulatum JCM 30316T. Based on the findings from its phenotypic, genotypic and phylogenetic analyses, N1Y112T is considered to represent a novel species of the genus Pontibacterium , for which the name Pontibacterium sinense sp. nov. is proposed. The type strain is N1Y112T (=KCTC 72927T=MCCC 1H00429T).