Tenacibaculum sediminilitoris sp. nov., isolated from a tidal flat.

A Gram-stain-negative, non-flagellated, non-gliding, non-spore-forming bacterial strain, designated YKTF-3T, was isolated from a tidal flat on the Yellow Sea, South Korea. Strain YKTF-3T grew optimally at 30 °C and in the presence of 2.0-4.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences showed that strain YKTF-3T fell within the clade comprising the type strains of Tenacibaculumspecies. The novel strain exhibited 16S rRNA gene sequence similarity values of 97.22-98.34 % to the type strains of Tenacibaculum gallaicum, Tenacibaculum ascidiaceicola, Tenacibaculum litoreum, Tenacibaculum discolor, Tenacibaculum aestuarii and Tenacibaculum lutimaris, and of 95.08-96.95 % to the type strains of the other Tenacibaculum species. Strain YKTF-3T contained MK-6 as the predominant menaquinone and iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and iso-C17 : 0 3-OH as the major fatty acids. The major polar lipids of strain YKTF-3T were phosphatidylethanolamine, one unidentified lipid, one unidentified aminophospholipid, one unidentified glycolipid and one unidentified aminolipid. The DNA G+C content was 32.3 mol% and its mean DNA-DNA relatedness values with the type strains of the six phylogenetically closely relatedTenacibaculum species were 10-27 %. Differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain YKTF-3T is separate from other recognized species of the genus Tenacibaculum. On the basis of the data presented, strain YKTF-3T is considered to represent a novel species of the genus Tenacibaculum, for which the name Tenacibaculum sediminilitoris sp. nov. is proposed. The type strain is YKTF-3T (=KCTC 52210T=NBRC 111991T).

In vitro quenching of fish pathogen Edwardsiella tarda AHL production using marine bacterium Tenacibaculum sp. strain 20J cell extracts.

Quorum quenching (QQ) has become an interesting alternative for solving the problem of bacterial antibiotic resistance, especially in the aquaculture industry, since many species of fish-pathogenic bacteria control their virulence factors through quorum sensing (QS) systems mediated by N-acylhomoserine lactones (AHLs). In a screening for bacterial strains with QQ activity in different marine environments, Tenacibaculum sp. strain 20J was identified and selected for its high degradation activity against a wide range of AHLs. In this study, the QQ activity of live cells and crude cell extracts (CCEs) of strain 20J was characterized and the possibilities of the use of CCEs of this strain to quench the production of AHLs in cultures of the fish pathogen Edwardsiella tarda ACC35.1 was explored. E. tarda ACC35.1 produces N-hexanoyl-L-homoserine lactone (C6-HSL) and N-oxohexanoyl-L-homoserine lactone (OC6-HSL). This differs from profiles registered for other E. tarda strains and indicates an important intra-specific variability in AHL production in this species. The CCEs of strain 20J presented a wide-spectrum QQ activity and, unlike Bacillus thuringiensis serovar Berliner ATCC10792 CCEs, were effective in eliminating the AHLs produced in E. tarda ACC35.1 cultures. The fast and wide-spectrum AHL-degradation activity shown by this member of the Cytophaga-Flexibacter-Bacteroidetes group consolidates this strain as a promising candidate for the control of AHL-based QS pathogens, especially in the marine fish farming industry.

Tenacibaculum jejuense sp. nov., isolated from coastal seawater.

A Gram-staining-negative, strictly aerobic and rod-shaped bacterium, designated strain CNURIC013(T), was isolated from seawater collected on the coast of Jeju Island, South Korea. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain CNURIC013(T) belonged to the genus Tenacibaculum, within the family Flavobacteriaceae. Sequence similarities between the novel strain and the type strains of recognized species of the genus Tenacibaculum were 93.6-96.0 %, the highest value being with Tenacibaculum litopenaei B-I(T) (96 %). The DNA G+C content of the novel strain was 34.5 mol% and the major respiratory quinone was menaquinone-6. The major fatty acids were summed feature 3 (comprising C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH; 26.0 %), iso-C(15 : 0) (24.4 %), iso-C(15 : 1) G (18.5 %) and iso-C(17 : 0) 3-OH (8.1 %). The polar lipids consisted of phosphatidylethanolamine, one unknown aminophospholipid and nine unknown polar lipids. On the basis of the phenotypic, phylogenetic and genotypic data, strain CNURIC013(T) represents a novel species within the genus Tenacibaculum, for which the name Tenacibaculum jejuense sp. nov. is proposed. The type strain is CNURIC013(T) ( = KCTC 22618(T) = JCM 15975(T)).

Tenacibaculum dicentrarchi sp. nov., a marine bacterium of the family Flavobacteriaceae isolated from European sea bass.

A novel Gram-stain-negative rod-shaped gliding bacterial strain, designated 35/09(T), was isolated from diseased European sea bass (Dicentrarchus labrax L.) in Spain. Colonies were pale-yellow-pigmented with uneven edges and did not adhere to the agar. The DNA G+C content of the isolate was 31.3 mol%. 16S rRNA gene sequence analysis indicated affiliation to the genus Tenacibaculum (family Flavobacteriaceae, phylum 'Bacteroidetes'). Sequence similarities between the isolate and type strains of other members of the genus were 93.1-97.3 %. The major fatty acids (>5 % of the total fatty acids) were iso-C(15 : 0) (24.8 %), iso-C(15 : 0) 3-OH (18.0 %), anteiso-C(15 : 0) (8.1 %), C(15 : 1)ω6c (6.9 %) and iso-C(15 : 1) (6.2 %). Genotypic and phenotypic data indicate that strain 35/09(T) should be classified as a representative of a novel species in the genus Tenacibaculum, for which the name Tenacibaculum dicentrarchi sp. nov. is proposed; the type strain is 35/09(T) ( = CECT 7612(T) = NCIMB 14598(T)).