Vibrio nitrifigilis sp. nov., a marine nitrogen-fixing bacterium isolated from the lagoon sediment of an islet inside an atoll.

Abstract

A nitrogen-fixing isolate of facultatively anaerobic, marine bacterium, designated strain NFV-1T, was recovered from the lagoon sediment of Dongsha Island, Taiwan. It was a Gram-negative rod which exhibited motility with monotrichous flagellation in broth cultures. The strain required NaCl for growth and grew optimally at about 25-35°C, 3% NaCl and pH 7-8. It grew aerobically and could achieve anaerobic growth by fermenting D-glucose or other carbohydrates as substrates. NH4Cl could serve as a sole nitrogen source for growth aerobically and anaerobically, whereas growth with N2 as the sole nitrogen source was observed only under anaerobic conditions. Cellular fatty acids were predominated by C16:1 ω7c, C16:0, and C18:1 ω7c. The major polar lipids consisted of phosphatidylethanolamine and phosphatidylserine. Strain NFV-1T had a DNA G + C content of 42.5mol%, as evaluated according to the chromosomal DNA sequencing data. Analyses of sequence similarities and phylogeny based on the 16S rRNA genes, together with the housekeeping genes, gyrB, ftsZ, mreB, topA and gapA, indicated that the strain formed a distinct species-level lineage in the genus Vibrio of the family Vibrionaceae. These phylogenetic data and those from genomic and phenotypic characterisations support the establishment of a novel Vibrio species, for which the name Vibrio nitrifigilis sp. nov. (type strain NFV-1T = BCRC 81211T = JCM 33628T) is proposed.