Pseudogracilibacillus marinus sp. nov., isolated from a biofilm formed in coastal seawater

Abstract

A Gram-staining-positive, aerobic, motile, rod-shaped (0.4-0.5×2.0-4.0 µm), endospore-forming bacterium, designated strain NIOT.bflm.S4T, was isolated from biofilm formed on high-density polyethylene test coupons in coastal seawater. The strain required seawater for growth. It grew with 1.0-8.0 % (w/v) NaCl, at 4-45 °C and at pH 6.5-9.0, with optimum growth with 4.0-5.0 % (w/v) NaCl, at 30 °C and at pH 7.0-8.0. Phylogenetic analyses based on 16S rRNA and partial dnaK gene sequences showed that strain NIOT.bflm.S4T formed a phylogenetic lineage with Pseudogracilibacillus auburnensis P-207T, the only known species of the genus Pseudogracilibacillusand shared sequence identities of 96.9 and 83 %, respectively, with this strain. The identities of 16S rRNA and partial dnaK gene sequences with members of other related genera such as Gracilibacillus, Paraliobacillus, Ornithinibacillus, Oceanobacillus, Virgibacillus and Lentibacillus were ≤95 and ≤78 %, respectively. The DNA G+C content of strain NIOT.bflm.S4T was 39.1 mol%. MK-7 was found as the sole isoprenoid quinone. The major polar lipids of strain NIOT.bflm.S4T were diphosphatidylglycerol, phosphatidylethanolamine and an unknown lipid. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. Major cellular fatty acids were anteiso-C15 : 0 (27.9 %), anteiso-C17 : 0 (18.6 %), C12 : 0 (8.7 %) and iso-C15 : 0 (6.6 %). On the basis of phenotypic, phylogenetic and chemotaxonomic results, we propose that the isolate represents a novel species of the genus Pseudogracilibacillus, for which the name Pseudogracilibacillus marinus sp. nov. is proposed. The type strain is NIOT.bflm.S4T (=KACC 18456T=MTCC 12376T=TBRC 5831T).