Spongiispira norvegica gen. nov., sp. nov., a marine bacterium isolated from the boreal sponge Isops phlegraei.

The bacterial strain Gp_4_7.1T, isolated from the marine sponge Isops phlegraei collected at the Sula Ridge off the Norwegian coast, was characterized. The isolate was a motile spirillum that was monopolarly and monotrichously flagellated. It was aerobic, Gram-negative, oxidase-positive and catalase-negative. Optimal growth occurred between 20 and 30 degrees C, at pH 7-8 and with a salt concentration of 2-3 % (w/v). The isolate showed a relatively restricted nutritional profile. Substrate utilization tests were only positive for arabinose. Enzyme tests were positive for esterase lipase C8, lipase C14, leucine arylamidase and naphthol-AS-BI-phosphohydrolase. The strain was not able to reduce nitrate. The major cellular fatty acids were C16:1 omega7 and C16:0. The DNA G+C content was 62.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparison classified the strain as a member of the order Oceanospirillales in the class Gammaproteobacteria. Strain Gp_4_7.1T formed a distinct phyletic line with less than 94 % 16S rRNA gene sequence similarity to its closest relatives with validly published names. Based on the determined data, it is proposed that the strain represents a novel species in a new genus, Spongiispira norvegica gen. nov., sp. nov.; the type strain of Spongiispira norvegica is Gp_4_7.1T (=DSM 17749T =NCIMB 14401T).

Spongiibacter marinus gen. nov., sp. nov., a halophilic marine bacterium isolated from the boreal sponge Haliclona sp. 1.

Strain HAL40b(T) was isolated from the marine sponge Haliclona sp. 1 collected at the Sula Ridge off the Norwegian coast and characterized by physiological, biochemical and phylogenetic analyses. The isolate was a small rod with a polar flagellum. It was aerobic, Gram-negative and oxidase- and catalase-positive. Optimal growth was observed at 20-30 degrees C, pH 7-9 and in 3 % NaCl. Substrate utilization tests were positive for arabinose, Tween 40 and Tween 80. Enzyme tests were positive for alkaline phosphatase, esterase lipase (C8), leucine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase and N-acetyl-beta-glucosaminidase. The predominant cellular fatty acid was C(17 : 1) omega8, followed by C(17 : 0) and C(18 : 1) omega7. Analysis by matrix-assisted laser desorption/ionization time-of-flight MS was used to characterize the strain, producing a characteristic low-molecular-mass protein pattern that could be used as a fingerprint for identification of members of this species. The DNA G+C content was 69.1 mol%. Phylogenetic analysis supported by 16S rRNA gene sequence comparison classified the strain as a member of the class Gammaproteobacteria. Strain HAL40b(T) was only distantly related to other marine bacteria including Neptunomonas naphthovorans and Marinobacter daepoensis (type strain sequence similarity >90 %). Based on its phenotypic, physiological and phylogenetic characteristics, it is proposed that the strain should be placed into a new genus as a representative of a novel species, Spongiibacter marinus gen. nov., sp. nov.; the type strain of Spongiibacter marinus is HAL40b(T) (=DSM 17750(T) =CCUG 54896(T)).

Bacillus plakortidis sp. nov. and Bacillus murimartini sp. nov., novel alkalitolerant members of rRNA group 6.

The Gram-positive, alkali- and salt-tolerant marine bacterium strain P203(T) is described together with its closest phylogenetic neighbour, terrestrial isolate LMG 21005(T). Strain P203(T) was isolated from material from the sponge Plakortis simplex that was obtained from the Sula-Ridge, Norwegian Sea. Strain LMG 21005(T) was an undescribed strain that was isolated from a church wall mural in Germany. Strains P203(T) and LMG 21005(T) were identified as novel alkalitolerant members of the Bacillus rRNA group 6 with a 16S rRNA gene sequence similarity of 99.5 %. The closest described neighbour, Bacillus gibsonii DSM 8722(T), showed 99.0 % gene sequence similarity with P203(T) and 98.8 % similarity with strain LMG 21005(T). Despite the high 16S rRNA gene sequence similarity, DNA-DNA cross-hybridization revealed only 25.8-34.1 % similarity amongst the three strains. The DNA G+C contents were 41.1 mol% for strain P203(T) and 39.6 mol% for strain LMG 21005(T). Both strains grew well between pH 7 and pH 11. Strain P203(T) showed growth at moderate temperatures (from 4 to 30 degrees C) and in the presence of up to 12 % (w/v) NaCl at pH 9.7, whereas strain LMG 21005(T) was not salt tolerant (up to 4 % NaCl) and no growth was observed at 4 degrees C. The major fatty acids of strains P203(T), LMG 21005(T) and the type strain of B. gibsonii were the saturated terminally methyl-branched compounds iso-C(15 : 0) (19.8, 15.6 and 28.0 %, respectively) and anteiso-C(15 : 0) (57.1, 48.6 and 45.2 %, respectively). Physiological and biochemical tests allowed genotypic and phenotypic differentiation of strains P203(T) and LMG 21005(T) from the six related Bacillus species with validly published names and supported the proposal of two novel species, Bacillus plakortidis [type strain P203(T) (=DSM 19153(T)=NCIMB 14288(T))] and Bacillus murimartini [type strain LMG 21005(T) (=NCIMB 14102(T))].

A marine Mesorhizobium sp. produces structurally novel long-chain N-acyl-L-homoserine lactones.

Our study focused on a Mesorhizobium sp. that is phylogenetically affiliated by 16S rRNA gene sequence to other marine and saline bacteria of this genus. Liquid chromatography-mass spectrometry investigations of the extract obtained from solid-phase extraction of cultures of this bacterium indicated the presence of several N-acyl homoserine lactones (AHLs), with chain lengths of C(10) to C(16). Chromatographic separation of the active bacterial extract yielded extraordinarily large amounts of two unprecedented acylated homoserine lactones, 5-cis-3-oxo-C(12)-homoserine lactone (5-cis-3-oxo-C(12)-HSL) (compound 1) and 5-cis-C(12)-HSL (compound 2). Quorum-sensing activity of compounds 1 and 2 was shown in two different biosensor systems [Escherichia coli MT102(pSB403) and Pseudomonas putida F117(pKR-C12)]. Furthermore, it was shown that both compounds can restore protease and pyoverdin production of an AHL-deficient Pseudomonas aeruginosa PAO1 lasI rhlI double mutant, suggesting that these signal molecules maybe used for intergenus signaling. In conclusion, these data indicate that the quorum-sensing activity of compounds 1 and 2 is modulated by the chain length and functional groups of the acyl moiety. Additionally, compound 1 showed antibacterial and cytotoxic activities.