Uncovering potential interspecies signaling factors in plant-derived mixed microbial culture.

Microbes use signaling factors for intraspecies and interspecies communications. While many intraspecies signaling factors have been found and characterized, discovery of factors for interspecies communication is lagging behind. To facilitate the discovery of such factors, we explored the potential of a mixed microbial culture (MMC) derived from wheatgrass, in which heterogeneity of this microbial community might elicit signaling factors for interspecies communication. The stability of Wheatgrass MMC in terms of community structure and metabolic output was first characterized by 16S ribosomal RNA amplicon sequencing and liquid chromatography/mass spectrometry (LC/MS), respectively. In addition, detailed MS analyses led to the identification of 12-hydroxystearic acid (12-HSA) as one of the major metabolites produced by Wheatgrass MMC. Stereochemical analysis revealed that Wheatgrass MMC produces mostly the (R)-isomer, although a small amount of the (S)-isomer was also observed. Furthermore, 12-HSA was found to modulate planktonic growth and biofilm formation of various marine bacterial strains. The current study suggests that naturally derived MMCs could serve as a simple and reproducible platform to discover potential signaling factors for interspecies communication. In addition, the study indicates that hydroxylated long-chain fatty acids, such as 12-HSA, may constitute a new class of interspecies signaling factors.

Alteromonas ponticola sp. nov., a gammaproteobacterium isolated from seawater.

A Gram-stain-negative, aerobic, non-spore-forming, non-motile and ovoid or rod-shaped bacterial strain, MYP5T, was isolated from seawater in Jeju island of South Korea. MYP5T grew optimally at 30-35 °C and in the presence of 2.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that MYP5T fell within the clade enclosed by the type strains of species of the genus Alteromonas, clustering with the type strains of Alteromonas confluentis and Alteromonas halophila. MYP5T exhibited the highest 16S rRNA gene sequence similarity value (98.0 %) to the type strain of A. confluentis and similarities of 95.1-97.9 % to the type strains of the other species of the genus Alteromonas. ANI and dDDH values of genomic sequences between MYP5T and the type strains of 22 species of the genus Alteromonas were 66.8-70.5 % and 18.6-27.5 %, respectively. The DNA G+C content of MYP5T, determined from the genome sequence, was 46.1 %. MYP5T contained Q-8 as the predominant ubiquinone and C18 : 1 ω7c, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C16 : 0 and 10-methyl C17 : 0 as the major fatty acids. The major polar lipids of MYP5T were phosphatidylethanolamine and phosphatidylglycerol. Distinguishing phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that MYP5T is separated from species of the genus Alteromonas. On the basis of the data presented, MYP5T is considered to represent a novel species of the genus Alteromonas, for which the name Alteromonas ponticola sp. nov. is proposed. The type strain is MYP5T (=KCTC 82144T=NBRC 114354T).

Alteromonas profundi sp. nov., isolated from the Indian Ocean.

A Gram-staining-negative bacterium, designated 345S023T, was isolated from a sea water sample from the Indian Ocean. The results of 16S rRNA gene sequence analysis revealed that 345S023T represents a member of the genus Alteromonas, with closely related type strains Alteromonas fortis 1T (98.7 %), Alteromonas hispanica F-32T (98.6 %) and Alteromonas genovensis LMG 24078T (98.6 %). Up-to-date bacterial core gene set analysis revealed that 345S023T formed a phyletic lineage with Alteromonas australica H 17T. The case for 345S023T representing a novel species was supported by genomic results. Pairwise in silico DNA-DNA hybridization and average nucleotide identity values were much lower than the proposed and generally accepted species boundaries. Strain 345S023T contains ubiquinone-8 (Q-8) as the sole isoprenoid quinone, summed featured 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c as the dominant cellular fatty acids (>10 %), and phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. The genome of strain 345S023T consisted of a 4.4 Mb chromosome with a DNA G+C content of 44.4 %. On the basis of these genomic, chemotaxonomic and phenotypic characteristics, we propose a novel species: Alteromonas profundi sp. nov. The type strain is 345S023T(=JCM 33893T=MCCC 1K04570T).

Alteromonas portus sp. nov., an alginate lyase-excreting marine bacterium.

An alginate lyase-excreting bacterium, designated strain HB161718T, was isolated from coastal sand collected from Tanmen Port in Hainan, PR China. Cells were Gram-stain-negative rods and motile with a single polar flagellum. Its major isoprenoid quinone was ubiquinone 8 (Q-8), and its cellular fatty acid profile mainly consisted of C16 : 1 ω7c and/or C16 : 1 ω6c, C18 : 1 ω6c and/or C18 : 1 ω7c, C16 : 0, C17 : 0 10-methyl and C16 : 0 N alcohol. The G+C content of the genomic DNA was 44.1 mol%. 16S rRNA gene sequence analysis suggested that strain HB161718T belonged to the genus Alteromonas, sharing 99.5, 99.4, 99.2, 98.9 and 98.5 % sequence similarities to its closest relatives, Alteromonas macleodii JCM 20772T, Alteromonas gracilis 9a2T, Alteromonas australica H17T, Alteromonas marina SW-47T and Alteromonas mediterranea DET, respectively. The low values of DNA-DNA hybridization and average nucleotide identity showed that it formed a distinct genomic species. The combined phenotypic and molecular features supported the conclusion that strain HB161718T represents a novel species of the genus Alteromonas, for which the name Alteromonas portus sp. nov. is proposed. The type strain is HB161718T (=CGMCC 1.13585T=JCM 32687T).

Alteromonas alba sp. nov., a marine bacterium isolated from seawater of the West Pacific Ocean.

A Gram-stain-negative, strictly aerobic, motile by one polar flagellum, non-spore-forming, rod-shaped bacterium, designated as 190T, was isolated from seawater of the West Pacific Ocean and subjected to a polyphasic taxonomic investigation. Colonies were 1.0-2.0 mm in diameter, smooth, circular, convex and white after growth on marine agar at 30 °C for 24 h. Strain 190T was found to grow at 4-40 °C (optimum, 30 °C), at pH 5.5-10.5 (optimum, pH 6.5) and with 0.5-12.5 % (w/v) NaCl (optimum, 2.0 %). Chemotaxonomic analysis showed the sole respiratory quinone was ubiquinone 8 (Q-8), and the major fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The major polar lipids were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), one unidentified aminolipid (AL1) and two unidentified glycolipids (GL1, GL2). The DNA G+C content of strain 190T was 48.7 mol% based on the genome sequence. The comparison of 16S rRNA gene sequence similarities showed that strain 190T was closely related to Alteromonas oceani S35T (99.6 % sequence similarity), A. lipolytica JW12T (98.2 %), A. aestuariivivens JDTF-113T (97.7 %) and A. mediterranea DET (97.5 %); it exhibited 97.0 % or less sequence similarity with the type strains of other species with validly published names. Phylogenetic trees reconstructed with the neighbour-joining, maximum-parsimony and maximum-likelihood methods based on 16S rRNA gene sequences showed that strain 190T constituted a separate branch with A. oceani, A. confluentis, A. aestuariivivens and A. lipolytica in a clade of the genus Alteromonas. OrthoANI values between strain 190T and A. oceani S35T and A. lipolytica JW12T were 93.5 and 77.9 %, respectively, and in silico DNA-DNA hybridization values were 53.8 and 21.2 %, respectively. Differential phenotypic properties, together with phylogenetic distinctiveness, demonstrated that strain 190T is clearly distinct from recognized species of the genus Alteromonas. On the basis of these features, we propose that strain 190T (=MCCC 1K03456T=KCTC 62227T) represents a novel species of the genus Alteromonas with the name Alteromonas alba sp. nov.

Alteromonas sediminis sp. nov., isolated from sediment in a sea cucumber culture pond.

A novel strain, U0105T, was isolated from marine sediment of the coast of Weihai, China. The bacterium was aerobic, Gram-stain-negative, oxidase-positive, catalase-positive, rod-shaped and motile. Growth was observed at salinities of 1.0-6.0 % (w/v) NaCl (optimum with 2.0-3.0 %), temperatures of 20-40 °C (optimum at 37 °C) and pH of 6.5-9.5 (optimum at pH 7.0-7.5). The isolate could not reduce nitrate to nitrite. It could hydrolyse starch and Tweens 20, 40 and 60, but not casein or cellulose. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain U0105T belonged to the genus Alteromonas, with highest sequence similarity to Alteromonas aestuariivivens KCTC 52655T (97.1 %). The average nucleotide identity value and the digital DNA-DNA hybridization value between strain U0105T and A. aestuariivivens KCTC 52655T were 69.2 % and 21.2 %, respectively. Strain U0105T was found to contain Q-8 as the sole menaquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c as the major fatty acids. The major polar lipids were identified as phosphatidylglycerol and phosphatidylethanolamine. The G+C content of the chromosomal DNA was 45.3 mol%. The combined genotypic and phenotypic data show that strain U0105T represents a novel species of the genus Alteromonas, for which the name Alteromonas sediminis sp. nov. is proposed. The type strain is U0105T (=KCTC 62080T=MCCC 1H00299T).

Alteromonas fortis sp. nov., a non-flagellated bacterium specialized in the degradation of iota-carrageenan, and emended description of the genus Alteromonas.

Strain 1T, isolated in the 1970s from the thallus of the carrageenophytic red algae, Eucheuma spinosum, collected in Hawaii, USA, was characterized using a polyphasic method. Cells were Gram-stain-negative, strictly aerobic, non-flagellated, ovoid or rod-shaped and grew optimally at 20-25 °C, at pH 6-9 and with 2-4 % NaCl. Strain 1T used the seaweed polysaccharides ι-carrageenan, laminarin and alginic acid as sole carbon sources. The major fatty acids were C16 : 0, C18 : 1 ω7c and summed feature 3 (C16 : 1 ω7c and/or iso-C15 : 0 2OH) with significant amounts (>6 %) of C16 : 0 N alcohol and 10 methyl C17 : 0. The respiratory quinone was Q-8 and major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and an unknown aminolipid. Phylogenetic analyses showed that the bacterium is affiliated to the genus Alteromonas (family Alteromonadaceae, class Gammaproteobacteria). Strain 1T exhibited 16S rRNA gene sequence similarity values of 98.8 and 99.2 % to the type strains of Alteromonas mediterranea and Alteromonas australica respectively, and of 95.2-98.6 % to other species of the genus Alteromonas. The DNA G+C content of strain 1T was determined to be 43.9 mol%. Digital DNA-DNA hybridization predictions by the ANI and GGDC methods between strain 1T and other members of the genus Alteromonas showed values below 83 % and 30 %, respectively. The phenotypic, phylogenetic and genomic analyses show that strain 1T is distinct from species of the genus Alteromonas with validly published names and that it represents a novel species of the genus Alteromonas, for which the name Alteromonasfortis sp. nov. is proposed. The type strain is 1T (=ATCC 43554T=RCC 5933T=CIP 111645T=DSM 106819T).

Alteromonas indica sp. nov., isolated from surface seawater from the Indian Ocean.

A Gram-stain-negative bacterium, designated strain IO390401T, was isolated from a seawater sample from the sulphide region of the Indian Ocean. Phylogenetic trees based on 16S rRNA gene sequences showed that strain IO390401T is a member of the genus Alteromonas, sharing 97.0-97.4 % 16S rRNA gene sequence similarity with Alteromonas additaR10SW13T, A. stellipolaris LMG 21861T, A. naphthalenivorans JCM 17741T, A. gracilis 9a2T and A. australica H17T, and 94.8-96.8 % with the type strains of other species of the genus Alteromonas. Strain IO390401T contained ubiquinone-8 (Q-8) as the sole isoprenoid quinone, C16:0 and C16:1ω7c/C16:1ω6c as the dominant cellular fatty acids, and phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. The genome of strain IO390401T consists of a 4.4 Mb chromosome with a G+C content of 48.2 mol%. Average nucleotide identity values between strain IO390401T and the three closest phylogenetic neighbours, namely A. additaR10SW13T, A. stellipolaris LMG 21861T and A. naphthalenivorans JCM 17741T, were 70.5, 70.4 and 70.6 %, respectively, and the corresponding in silico DNA-DNA hybridization values were 20.6, 20.7 and 21.1 %. Phylogenetic distinctiveness and chemotaxonomic differences, together with phenotypic properties determined in this study, revealed that strain IO390401T could be differentiated from closely related species. It is therefore proposed as representing a novel species in the genus Alteromonas, for which the name Alteromonas indica sp. nov. is suggested. The type strain is IO390401T (=JCM 32638T=CGMCC 1.13554T=CCTCC AB 2018072T).

Alteromonas oceani sp. nov., isolated from deep-sea sediment of a hydrothermal field.

A novel rod-shaped, Gram-stain-negative, aerobic bacterium, designated S35T, was isolated from deep-sea sediment collected from the Pacmanus hydrothermal field, Manus Basin, Papua New Guinea. Strain S35T grew optimally at 28 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. 16S rRNA gene sequence analysis indicated that strain S35T shared 97.38-98.55% similarity with the type strains of Alteromonas lipolytica, Alteromonas mediterranea and Aestuariibacterhalophilus. Phylogenetic analysis showed that strain S35T belonged to the genus Alteromonas. The strain contained ubiquinone-8 as the predominant respiratory lipoquinone. Summed feature 3 (C16 : 1ω7c and/or C16 : 1ω7c), summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0 were the major fatty acids. The DNA G+C content of strain S35T was 51.3 mol%. These results indicated that strain S35T represents a novel species of the genus Alteromonas, for which the name Alteromonas oceani sp. nov. (type strain S35T=KCTC 52449T=CGMCC 1.16029T) is proposed.

Description of Alteromonas abrolhosensis sp. nov., isolated from sea water of Abrolhos Bank, Brazil.

Two Gram-negative, motile, aerobic bacteria isolated from waters of the Abrolhos Bank were classified through a whole genome-based taxonomy. Strains PEL67ET and PEL68C shared 99% 16S rRNA and dnaK sequence identity with Alteromonas marina SW-47T and Alteromonas macleodii ATCC 27126T. In silico DNA-DNA Hybridization, i.e. genome-to-genome distance (GGD), average amino acid identity (AAI) and average nucleotide identity (ANI) showed that PEL67ET and PEL68C had identity values between 33-36, 86-88 and 83-84%, and 85-86 and 83%, respectively, towards their close neighbors A. macleodii ATCC 27126T and A. marina SW-47T. The DNA G + C contents of PEL67ET and PEL68C were 44.5%. The phenotypic features that differentiate PEL67ET and PEL68C strains from their close neighbors were assimilation of galactose and activity of phosphatase, and lack of mannitol, maltose, acetate, xylose and glycerol assimilation and lack of lipase, α and ß-glucosidase activity. The new species Alteromonas abrolhosensis is proposed. The type strain is PEL67ET (= CBAS 610T = CAIM 1925T).

Alteromonas pelagimontana sp. nov., a marine exopolysaccharide-producing bacterium isolated from the Southwest Indian Ridge.

A novel exopolysaccharide-producing strain, designated as 5.12T, was isolated from a sediment sample from the Southwest Indian Ridge, Indian Ocean. The strain was Gram-stain-negative, motile, strictly aerobic, and oxidase- and catalase-positive. It grew optimally at 35 °C, at pH 6.0 and in the presence of 3.5 % (w/v) NaCl. Its major isoprenoid quinone was ubiquinone-8 (Q-8) and summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0 and C18 : 1ω7c were the major cellular fatty acids. The DNA G+C content was 46.1 mol%. 16S rRNA gene sequence analysis suggested that strain 5.12T is a member of the genus Alteromonas. Strain 5.12T exhibited close 16S rRNA gene sequence similarity to Alteromonas lipolytica JW12T (96.1 %), Alteromonas hispanica F-32T (95.9 %), Alteromonas confluentis DSSK2-12T (95.9 %), Alteromonas litorea TF-22T (95.6 %) and Alteromonas mediterranea DET (95.5 %). Strain 5.12T contained phosphatidylethanolamine and phosphatidylglycerol as the major polar lipids. Owing to significant differences in the 16S rRNA gene sequences, as well as the phenotypic and chemotaxonomic characteristics, the novel isolate described here merits classification as a representative of a novel species of the genus Alteromonas, for which the name Alteromonas pelagimontana sp. nov. is proposed. The type strain of this species is 5.12T (LMG 29661T= MCC 3250T).

Alteromonas aestuariivivens sp. nov., isolated from a tidal flat.

A Gram-stain-negative, aerobic, non-spore-forming, motile and ovoid or rod-shaped bacterial strain, JDTF-113T, was isolated from a tidal flat in Jindo, an island of South Korea. Strain JDTF-113T grew optimally at 30 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree, based on 16S rRNA gene sequences, revealed that strain JDTF-113T fell within the clade enclosing the type strains of species of the genus Alteromonas. Strain JDTF-113T exhibited 16S rRNA gene sequence similarity values of 97.1-98.1 % to the type strains of Alteromonaslipolytica, Alteromonaslitorea, Alteromonasmediterranea, Alteromonasconfluentis, Alteromonas hispanica, Alteromonasgenovensis and Alteromonasmarina, and of 94.8-96.9 % to those of the other species of the genus Alteromonas. Strain JDTF-113T contained Q-8 as the predominant ubiquinone and C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C18 : 1ω7c as the major fatty acids. The major polar lipids of strain JDTF-113T were phosphatidylethanolamine, phosphatidylglycerol and one unidentified glycolipid. The DNA G+C content of strain JDTF-113T was 51.1 mol% and its mean DNA-DNA relatedness values with the type strains of seven closely phylogenetically related species of the genus Alteromonaswere was 10-23 %. The differential phenotypic properties and phylogenetic and genetic distinctiveness support strain JDTF-113T being separated from species of the genus Alteromonaswith validly publishednames. On the basis of the data presented, strain JDTF-113T is considered to represent a novel species of the genus Alteromonas, for which the name Alteromonas aestuariivivens sp. nov. is proposed. The type strain is JDTF-113T (=KCTC 52655T=NBRC 112708T).

Alteromonas lipolytica sp. nov., a poly-beta-hydroxybutyrate-producing bacterium isolated from surface seawater.

Strain JW12T, isolated from surface seawater of the Arabian Sea, was subjected to characterization by a polyphasic taxonomic approach. Cells of the isolate were Gram-stain-negative, aerobic and rod-shaped. It accumulated poly-ß-hydroxybutyrate. On the basis of 16S rRNA gene sequence analysis, strain JW12T was closely related to Alteromonas confluentis, with 16S rRNA gene sequence similarity of 98.0 %. Phylogenetic analysis revealed that it fell within the cluster of the genus Alteromonas and represented one independent lineage with A. confluentis. The average nucleotide identity (ANI) value and the genome-to-genome distance between strain JW12T and A. confluentis KCTC 42603T were 70.0 and 21.3 %, respectively. The sole respiratory quinone was ubiquinone-8 (Q8). The principal fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and C18 : 1ω7c. The major polar lipids included phosphatidylethanolamine, phosphatidylglycerol, two unidentified glycolipids and one aminophospholipid. The DNA G+C content was 48.4 mol%. Differential phylogenetic distinctiveness and chemotaxonomic differences, together with phenotypic properties obtained in this study, revealed that strain JW12T could be differentiated from the closely related species. Therefore, it is proposed that strain JW12T represents a novel species in the genus Alteromonas, for which the name Alteromonas lipolytica sp. nov. (type strain, JW12T=CGMCC 1.15735T=KCTC 52408T=MCCC 1K03175T), is proposed.

Response of bacterial communities from California coastal waters to alginate particles and an alginolytic Alteromonas macleodii strain.

Alginate is a major cell wall polysaccharide from marine macroalgae and nutrient source for heterotrophic bacteria. Alginate can form gel particles in contact with divalent cations as found in seawater. Here, we tested the hypothesis that alginate gel particles serve as carbon source and microhabitat for marine bacteria by adding sterile alginate particles to microcosms with seawater from coastal California, a habitat rich in alginate-containing macroalgae. Alginate particles were rapidly colonized and degraded, with three- to eightfold higher bacterial abundances and production among alginate particle-associated (PA) bacteria. 16S rRNA gene amplicon sequencing showed that alginate PA bacteria were enriched in OTUs related to Cryomorphaceae, Saprospiraceae (Bacteroidetes) and Phaeobacter (Alphaproteobacteria) towards the end of the experiment. In microcosms amended with alginate particles and the proficient alginolytic bacterium Alteromonas macleodii strain 83-1, this strain dominated the community and outcompeted Cryomorphaceae, Saprospiraceae and Phaeobacter, and PA hydrolytic activities were over 50% higher. Thus, alginolytic activity by strain 83-1 did not benefit non-alginolytic strains by cross-feeding on alginate hydrolysis or other metabolic products. Considering the global distribution and extensive biomass of alginate-containing macroalgae, the observed bacterial dynamics associated with the utilization and remineralization of alginate microhabitats promote the understanding of carbon cycling in macroalgae-rich waters worldwide.

Different utilization of alginate and other algal polysaccharides by marine Alteromonas macleodii ecotypes.

The marine bacterium Alteromonas macleodii is a copiotrophic r-strategist, but little is known about its potential to degrade polysaccharides. Here, we studied the degradation of alginate and other algal polysaccharides by A. macleodii strain 83-1 in comparison to other A. macleodii strains. Cell densities of strain 83-1 with alginate as sole carbon source were comparable to those with glucose, but the exponential phase was delayed. The genome of 83-1 was found to harbour an alginolytic system comprising five alginate lyases, whose expression was induced by alginate. The alginolytic system contains additional CAZymes, including two TonB-dependent receptors, and is part of a 24 kb genomic island unique to the A. macleodii 'surface clade' ecotype. In contrast, strains of the 'deep clade' ecotype contain only a single alginate lyase in a separate 7 kb island. This difference was reflected in an eightfold greater efficiency of surface clade strains to grow on alginate. Strain 83-1 furthermore hydrolysed laminarin, pullulan and xylan, and corresponding polysaccharide utilization loci were detected in the genome. Alteromonas macleodii alginate lyases were predominantly detected in Atlantic Ocean metagenomes. The demonstrated hydrolytic capacities are likely of ecological relevance and represent another level of adaptation among A. macleodii ecotypes.

Alteromonas confluentis sp. nov., isolated from the junction between the ocean and a freshwater spring.

A Gram-stain-negative, aerobic, non-spore-forming, non-flagellated and coccoid, ovoid or rod-shaped bacterial strain, DSSK2-12T, was isolated from the place where the ocean and a freshwater spring meet at Jeju island, South Korea. Strain DSSK2-12T grew optimally at 30 °C, at pH 7.0­8.0 and in the presence of 2.0 % (w/v) NaCl. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain DSSK2-12T fell within the clade comprising the type strains of species of the genus Alteromonas. Strain DSSK2-12T exhibited 16S rRNA gene sequence similarity values of 97.2­98.1 % to the type strains of Alteromonas litorea, Alteromonas marina, Alteromonas hispanica and Alteromonas genovensis and of 95.39­96.98 % to those of other species of the genus Alteromonas. Strain DSSK2-12T contained Q-8 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c as the major fatty acids. The major polar lipids of strain DSSK2-12T were phosphatidylethanolamine, phosphatidylglycerol and one unidentified aminolipid. The DNA G+C content of strain DSSK2-12T was 48.6 mol% and its mean DNA­DNA relatedness values with the type strains of A. litorea, A. marina, A. hispanica and A. genovensis were 9­21 %. The differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain DSSK2-12T is separated from other species of the genus Alteromonas. On the basis of the data presented, strain DSSK2-12T is considered to represent a novel species of the genus Alteromonas, for which the name Alteromonas confluentis sp. nov. is proposed. The type strain is DSSK2-12T ( = KCTC 42603T = CECT 8870T).

Alteromonas naphthalenivorans sp. nov., a polycyclic aromatic hydrocarbon-degrading bacterium isolated from tidal-flat sediment.

A Gram-staining-negative and halotolerant bacterium, designated SN2T, capable of biodegrading polycyclic aromatic hydrocarbons, was isolated from a tidal flat contaminated with crude oil in Korea. Cells were strictly aerobic, catalase- and oxidase-positive, motile rods, with a single polar flagellum. Growth was observed at 4-37 °C (optimum, 25-30 °C) at pH 6.0-9.0 (optimum, pH 7.0-7.5) and in the presence of 0.5-9.0% (w/v) NaCl (optimum, 2.0%). Only ubiquinone 8 was detected as the isoprenoid quinone, and summed feature 3 (comprising C16:1ω7c and/or iso-C15:0 2-OH), C16:0, C18:1ω7c and C12:0 were observed as the major cellular fatty acids. The major polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, a glycolipid, an aminolipid and three unidentified lipids. The DNA G+C content was 43.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SN2T formed a phylogenetic lineage with Alteromonas stellipolaris and Alteromonas addita within the genus Alteromonas, which was consistent with multilocus phylogenetic and MALDI-TOF MS analyses. Strain SN2T was most closely related to the type strains of A. stellipolaris, A. addita and Alteromonas macleodii, with 16S rRNA gene sequence similarities of 99.5, 99.3 and 98.4% and DNA-DNA relatedness of 48.7 ± 6.6, 24.9 ± 7.5 and 27.9 ± 8.4%, respectively. In conclusion, strain SN2T represents a novel species of the genus Alteromonas, for which the name Alteromonas naphthalenivorans sp. nov. is proposed. The type strain is SN2T ( = KCTC 11700BPT = JCM 17741T =KACC 18427T).

Alteromonas gracilis sp. nov., a marine polysaccharide-producing bacterium.

A novel exopolysaccharide-producing bacterium, designated strain 9a2(T), was isolated from Pacific Ocean sediment. The strain was Gram-stain-negative, motile, strictly aerobic, oxidase- and catalase-positive, and required NaCl for growth. Its major isoprenoid quinone was ubiquinone-8 (Q-8), and its cellular fatty acid profile consisted mainly of C16 : 1ω7c, C18 : 1ω9c and C16 : 0. The DNA G+C content was 46.6 mol%. 16S rRNA gene sequence analysis suggested that strain 9a2(T) is a member of the genus Alteromonas . Strain 9a2(T) exhibited closest phylogenetic affinity to Alteromonas macleodii NBRC 102226(T) (99.3% 16S rRNA gene sequence similarity), A. marina SW-47(T) (99.3%), A. litorea TF-22(T) (99.0%), A. australica H17(T) (98.7%), A. simiduii BCRC 17572(T) (98.5%), A. stellipolaris LMG 21861(T) (98.3%) and A. hispanica F-32(T) (98.2%). The DNA-DNA reassociation values between strain 9a2(T) and A. macleodii JCM 20772(T), A. marina JCM 11804(T), A. litorea JCM 12188(T), A. australica CIP 109921(T), A. simiduii JCM 13896(T), A. stellipolaris LMG 21861(T) and A. hispanica LMG 22958(T) were below 70%. Strain 9a2(T) contained phosphatidylethanolamine, phosphatidylglycerol and an unidentified polar lipid. Owing to differences in phenotypic and chemotaxonomic characteristics, phylogenetic analysis based on 16S rRNA gene sequences and DNA-DNA relatedness data, the isolate merits classification as representing a novel species, for which the name Alteromonas gracilis sp. nov. is proposed. The type strain of this species is 9a2(T) ( =JCM 30236(T) =NCIMB 14947(T)).

Exopolysaccharide biosynthesis and biodegradation by a marine hydrothermal Alteromonas sp. strain.

Alteromonas macleodii subsp. fijiensis biovar deepsane is a deep-sea ecotype exopolysaccharide-producing bacteria isolated from the polychaete annelid Alvinella pompejana. The high molecular weight biopolymer HYD657 produced by this strain, is the first marine exopolysaccharide (EPS) to be commercialized for cosmetic use. Depolymerization methods are necessary to elucidate the complete structure of this EPS and to generate potentially bioactive oligosaccharides. Enzymatic methods are useful for elucidating polysaccharide structure because they specifically cleave glycosidic bonds and do not require harsh chemical conditions. The HYD657 EPS is structurally complex and no commercially available enzymes are able to effectively degrade it. Here, we present the first results on the endogenous enzymatic depolymerization of a marine EPS of biotechnological interest by the producing strain. Enzymatic activity was detected in the bacterial lysate and was able to decrease the apparent molecular size of the EPS, releasing mainly oligosaccharides. The reduced form of the native polysaccharide showed a slightly modified osidic composition, particularly in terms of molar ratio. Several exoglycosidase activities were measured in the bacterial lysate using paranitrophenyl-osides.

[FATTY ACID COMPOSITION ALTEROMONAS-LIKE BACTERIA ISOLATED FROM THE BLACK SEA WATER].

Alteromonas macleodii strains isolated from the Black sea water were similar in their fatty acids composition with the type strain of this species. Analysis of lipid composition of 10 A. macleodii strains isolated from the deep and surface water layers in different World ocean regions including the Black sea water has shown that the deep and surface isolates of this species formed two groups different in their fatty acids profiles. The Black sea isolates of Pseudoalteromonas haloplanktis, P. citrea, P. flavipulchra conformed to these species type strains in their fatty acids composition. On the basis of the fatty acids spectra similarity of three Pseudoalteromonas species strains with Plipolytica described in 2010 has been established. Presence of three isomers C16:1ψ7, C 16:1ψ9 and C16:1ψ6--components of hexadecenic acid in the Black sea isolates of Shewanella baltica has been shown.