Genus Aquimarina Research Articles

Aquimarina aquimarini sp. nov. and Aquimarina spinulae sp. nov., novel bacterial species with versatile natural product biosynthesis potential isolated from marine sponges.

This study describes two Gram-negative, flexirubin-producing, biofilm-forming, motile-by-gliding and rod-shaped bacteria, isolated from the marine sponges Ircinia variabilis and Sarcotragus spinosulus collected off the coast of Algarve, Portugal. Both strains, designated Aq135T and Aq349T, were classified into the genus Aquimarina by means of 16S rRNA gene sequencing. We then performed phylogenetic, phylogenomic and biochemical analyses to determine whether these strains represent novel Aquimarina species. Whereas the closest 16S rRNA gene relatives to strain Aq135T were Aquimarina macrocephali JAMB N27T (97.8 %) and Aquimarina sediminis w01T (97.1 %), strain Aq349T was more closely related to Aquimarina megaterium XH134T (99.2 %) and Aquimarina atlantica 22II-S11-z7T (98.1 %). Both strains showed genome-wide average nucleotide identity scores below the species level cut-off (95 %) with all Aquimarina type strains with publicly available genomes, including their closest relatives. Digital DNA-DNA hybridization further suggested a novel species status for both strains since values lower than 70 % hybridization level with other Aquimarina type strains were obtained. Strains Aq135T and Aq349T grew from 4 to 30°C and with between 1-5 % (w/v) NaCl in marine broth. The most abundant fatty acids were iso-C17 : 03-OH and iso-C15 : 0 and the only respiratory quinone was MK-6. Strain Aq135T was catalase-positive and β-galactosidase-negative, while Aq349T was catalase-negative and β-galactosidase-positive. These strains hold unique sets of secondary metabolite biosynthetic gene clusters and are known to produce the peptide antibiotics aquimarins (Aq135T) and the trans-AT polyketide cuniculene (Aq349T), respectively. Based on the polyphasic approach employed in this study, we propose the novel species names Aquimarina aquimarini sp. nov. (type strain Aq135T=DSM 115833T=UCCCB 169T=ATCC TSD-360T) and Aquimarina spinulae sp. nov. (type strain Aq349T=DSM 115834T=UCCCB 170T=ATCC TSD-361T).

Insights into the Antimicrobial Activities and Metabolomes of Aquimarina (Flavobacteriaceae, Bacteroidetes) Species from the Rare Marine Biosphere.

Two novel natural products, the polyketide cuniculene and the peptide antibiotic aquimarin, were recently discovered from the marine bacterial genus Aquimarina. However, the diversity of the secondary metabolite biosynthetic gene clusters (SM-BGCs) in Aquimarina genomes indicates a far greater biosynthetic potential. In this study, nine representative Aquimarina strains were tested for antimicrobial activity against diverse human-pathogenic and marine microorganisms and subjected to metabolomic and genomic profiling. We found an inhibitory activity of most Aquimarina strains against Candida glabrata and marine Vibrio and Alphaproteobacteria species. Aquimarina sp. Aq135 and Aquimarina muelleri crude extracts showed particularly promising antimicrobial activities, amongst others against methicillin-resistant Staphylococcus aureus. The metabolomic and functional genomic profiles of Aquimarina spp. followed similar patterns and were shaped by phylogeny. SM-BGC and metabolomics networks suggest the presence of novel polyketides and peptides, including cyclic depsipeptide-related compounds. Moreover, exploration of the ‘Sponge Microbiome Project’ dataset revealed that Aquimarina spp. possess low-abundance distributions worldwide across multiple marine biotopes. Our study emphasizes the relevance of this member of the microbial rare biosphere as a promising source of novel natural products. We predict that future metabologenomics studies of Aquimarina species will expand the spectrum of known secondary metabolites and bioactivities from marine ecosystems.

Aquimarina algicola sp. nov., isolated from the surface of a marine red alga.

A bacterial strain, designated M625T, was isolated from the surface of a marine red alga. Phylogenetic trees were reconstructed based on the 16S rRNA gene and RpoB protein sequences, which indicated that the strain belongs to the genus Aquimarina within the family Flavobacteriaceae. Strain M625T showed high sequence similarities to A. aggregata RZW4-3-2T (95.7%), A. seongsanensis CBA3208T (95.3%) and A. versatilis CBA3207T (95.0%). The AAI and POCP values between strain M625T and A. muelleri DSM 19832T were 71.8% and 57.9% respectively. The dDDH and ANI values between strain M625T and A. aggregata were 19.5% and 74.6% respectively. The strain was Gram-stain negative, strictly aerobic, non-motile and long rod-shaped, and positive for hydrolysis of starch, cellulose, alginate, DNA and Tween 20. The dominant respiratory quinone was MK-6. The major fatty acids were iso-C15:0, iso-C17:0 3-OH, and iso-C15:1 G, and the polar lipids consisted of phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminolipids, and seven unidentified lipids. Based on the polyphasic comparisons, strain M625T is proposed to represent a novel species within the genus Aquimarina, for which the name Aquimarina algicola sp. nov. (type strain M625T = MCCC 1H00399T = KCTC 72685T) was proposed.

Functional metagenomics reveals differential chitin degradation and utilization features across free-living and host-associated marine microbiomes

BackgroundChitin ranks as the most abundant polysaccharide in the oceans yet knowledge of shifts in structure and diversity of chitin-degrading communities across marine niches is scarce. Here, we integrate cultivation-dependent and -independent approaches to shed light on the chitin processing potential within the microbiomes of marine sponges, octocorals, sediments, and seawater.ResultsWe found that cultivatable host-associated bacteria in the genera Aquimarina, Enterovibrio, Microbulbifer, Pseudoalteromonas, Shewanella, and Vibrio were able to degrade colloidal chitin in vitro. Congruent with enzymatic activity bioassays, genome-wide inspection of cultivated symbionts revealed that Vibrio and Aquimarina species, particularly, possess several endo- and exo-chitinase-encoding genes underlying their ability to cleave the large chitin polymer into oligomers and dimers. Conversely, Alphaproteobacteria species were found to specialize in the utilization of the chitin monomer N-acetylglucosamine more often. Phylogenetic assessments uncovered a high degree of within-genome diversification of multiple, full-length endo-chitinase genes for Aquimarina and Vibrio strains, suggestive of a versatile chitin catabolism aptitude. We then analyzed the abundance distributions of chitin metabolism-related genes across 30 Illumina-sequenced microbial metagenomes and found that the endosymbiotic consortium of Spongia officinalis is enriched in polysaccharide deacetylases, suggesting the ability of the marine sponge microbiome to convert chitin into its deacetylated—and biotechnologically versatile—form chitosan. Instead, the abundance of endo-chitinase and chitin-binding protein-encoding genes in healthy octocorals leveled up with those from the surrounding environment but was found to be depleted in necrotic octocoral tissue. Using cultivation-independent, taxonomic assignments of endo-chitinase encoding genes, we unveiled previously unsuspected richness and divergent structures of chitinolytic communities across host-associated and free-living biotopes, revealing putative roles for uncultivated Gammaproteobacteria and Chloroflexi symbionts in chitin processing within sessile marine invertebrates.ConclusionsOur findings suggest that differential chitin degradation pathways, utilization, and turnover dictate the processing of chitin across marine micro-niches and support the hypothesis that inter-species cross-feeding could facilitate the co-existence of chitin utilizers within marine invertebrate microbiomes. We further identified chitin metabolism functions which may serve as indicators of microbiome integrity/dysbiosis in corals and reveal putative novel chitinolytic enzymes in the genus Aquimarina that may find applications in the blue biotechnology sector.4kjGuZRPCftKy_HwBHqQX8Video abstract

Characterization of Aquimarina hainanensis isolated from diseased mud crab Scylla serrata larvae in a hatchery.

Mass mortality due to necrosis signs occurred in hatchery-reared zoea stage larvae of the mud crab Scylla serrata in Okinawa, Japan, and a causative bacterium was isolated. In this study, we identified and characterized the bacterium by genome analysis, biochemical properties and pathogenicity. The bacterium was a Gram-negative, non-motile, long rod, forming yellow colonies on a marine agar plate. It grew at 20-33°C (not at 37°C) and degraded chitin and gelatin. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Aquimarina hainanensis. Genome sequence data obtained from Illumina MiSeq generated 29 contigs with 3.56Mbp in total length and a G+C content of 32.5%. The predicted 16 chitinase genes, as putative virulence factors, had certain homologies with those of genus Aquimarina. Experimental infection with the bacterium conducted on larvae of four crustacean species, brine shrimp Artemia franciscana, freshwater shrimp Caridina multidentata, swimming crab Portunus trituberculatus and mud crab S.serrata, revealed that this bacterium was highly virulent to these species. The present study suggests that the bacterium caused mass mortality in mud crab seed production was A.hainanensis and can be widely pathogenic to crustaceans.

Comparative genomics reveals complex natural product biosynthesis capacities and carbon metabolism across host-associated and free-living Aquimarina (Bacteroidetes, Flavobacteriaceae) species.

This study determines the natural product biosynthesis and full coding potential within the bacterial genus Aquimarina. Using comprehensive phylogenomics and functional genomics, we reveal that phylogeny instead of isolation source [host-associated (HA) vs. free-living (FL) habitats] primarily shape the inferred metabolism of Aquimarina species. These can be coherently organized into three major functional clusters, each presenting distinct natural product biosynthesis profiles suggesting that evolutionary trajectories strongly underpin their secondary metabolite repertoire and presumed bioactivities. Aquimarina spp. are highly versatile bacteria equipped to colonize HA and FL microniches, eventually displaying opportunistic behaviour, owing to their shared ability to produce multiple glycoside hydrolases from diverse families. We furthermore uncover previously underestimated, and highly complex secondary metabolism for the genus by detecting 928 biosynthetic gene clusters (BGCs) across all genomes, grouped in 439 BGC families, with polyketide synthases (PKSs), terpene synthases and non-ribosomal peptide synthetases (NRPSs) ranking as the most frequent BGCs encoding drug-like candidates. We demonstrate that the recently described cuniculene (trans-AT PKS) BGC is conserved among, and specific to, the here delineated A. megaterium-macrocephali-atlantica phylogenomic clade. Our findings provide a timely and in-depth perspective of an under-explored yet emerging keystone taxon in the cycling of organic matter and secondary metabolite production in marine ecosystems.

Aquimarina sediminis sp. nov., isolated from coastal sediment.

A strictly aerobic, Gram-stain negative, long rod-shaped, motile by gliding and yellow pigmented bacterium, designated strain w01T, was isolated from marine sediment. The strain was characterised to determine its taxonomic position by using a polyphasic approach. Strain w01T was observed to grow optimally in the presence of 3.0% (w/v) NaCl, at 30°C and to hydrolyse Tweens 20, 40 and 80, starch, casein and alginate. Carotenoid pigments were found to be produced but not flexirubin-type pigments. On the basis of 16S rRNA gene sequence similarities, strain w01T is phylogenetically affiliated with the genus Aquimarina and is closely related to Aquimarina macrocephali JCM 15542T (97.4% sequence similarity) and Aquimarina muelleri KCTC 12285T (97.0%). Lower sequence similarities (< 97.0%) were found with the other currently recognised members of the genus Aquimarina. The predominant fatty acids were identified as iso-C15:0 (33.7%), C18:0 3-OH (16.8%) and C17:1ω7c (10.6%). The polar lipid profile was found to contain phosphatidylethanolamine, an unidentified aminolipid and two unidentified polar lipids. MK-6 was identified as the sole respiratory quinone. The G + C content of the genomic DNA was determined to be 33.3mol%. Strain w01T can be differentiated genotypically and phenotypically from recognised species of the genus Aquimarina. The isolate is therefore concluded to represent a novel species, for which the name Aquimarina sediminis sp. nov. is proposed, with the type strain w01T (= KCTC 62350T = MCCC 1H00287T).

Aquimarina celericrescens sp. nov., isolated from seawater.

An orange-coloured, slender rod-shaped, gliding bacterium, designated NS08T, was isolated from coastal water of Xiaoshi Island, Weihai, China (37° 31' 36'' N 122° 00' 58'' E). Cells were Gram-stain-negative, non-spore-forming, non-flagellated, aerobic, catalase-positive and oxidase-negative. Growth occurred at 10-37 °C (optimum 30 °C), in the presence of 1.0-5.0 % (w/v) NaCl (optimum 2.0-3.0 %) and at pH 6.5-9.0 (optimum pH 7.0-7.5). Carotenoid pigments were produced but flexirubin-type pigments were not. The major fatty acids (>10 %) were iso-C15 : 0 and iso-C17 : 0 3-OH. The sole isoprenoid quinone of strain NS08T was menaquinone MK-6 and the DNA G+C content was 39.4 mol%. The polar lipid compositions of strain NS08T and the type strain of the type species of the genus Aquimarina, Aquimarina muelleri KCTC 12285T, were very similar with phosphatidylethanolamine, an unidentified aminolipid and two unknown polar lipids as the major components. A phylogenetic tree based on 16S rRNA gene sequences showed that strain NS08T formed an evolutionary lineage within the genus Aquimarina and shared the highest level of similarity to A. versatilis JCM 19528T (96.0 %) while level to A. muelleri KCTC 12285T was 95.0 %. Phenotypic characteristics distinguished strain NS08T from described members of the genus Aquimarina. On the basis of the evidence presented in this study, strain NS08T represents a novel species of the genus Aquimarina, for which the name Aquimarina celericrescens sp. nov. is proposed. The type strain is NS08T (=KCTC 52897T=MCCC 1H00191T).

Aquimarina spongiicola sp. nov., isolated from spongin.

A Gram-reaction-negative, aerobic, motile by gliding, non-spore-forming, rod-shaped bacterial strain, designated 122CH820-2T, was isolated from spongin. This bacterium was characterized to determine its taxonomic position by using a polyphasic approach. Strain 122CH820-2T grew well at 25-30 °C on marine agar. On the basis of 16S rRNA gene sequence similarity, strain 122CH820-2T belonged to the family Flavobacteriaceae and was closely related to Aquimarina mytili PSC33T (96.8 % sequence similarity) and A. penaei P3-1T (96.7 %). Lower sequence similarities (<96.5 %) were found with all of the other recognized members of the genus Aquimarina. The G+C content of the genomic DNA was 35.2 mol%. The major respiratory quinone was menaquinone MK-6 and the major fatty acids were C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 1 G and iso-C15 : 0 3-OH. The polar lipids were phosphatidylethanolamine, one aminophospholipid and five unidentified polar lipids. Strain 122CH820-2T could be differentiated genotypically and phenotypically from recognized species of the genus Aquimarina. The isolate therefore represents a novel species, for which the name Aquimarina spongiicola sp. nov. is proposed, with the type strain 122CH820-2T (=KACC 19274T=LMG 30078T).

Aquimarina algiphila sp. nov., a chitin degrading bacterium isolated from the red alga Tichocarpus crinitus.

A strictly aerobic, Gram-stain-negative, rod-shaped, motile by gliding and yellow-orange pigmented flavobacterium, designated strain 9Alg 151T, was isolated from the Pacific red alga Tichocarpus crinitus. Phylogenetic analysis based on 16S rRNA gene sequences showed that the novel strain fell into the genus Aquimarina of the family Flavobacteriaceae with a 16S rRNA gene sequence similarity range of 94.2-98.2 % to the recognized species of the genus. Strain 9Alg 151T grew in the presence of 0.5-5 % NaCl and at 5-34 °C, and hydrolysed aesculin, agar, gelatin, starch, Tween 40, DNA and chitin. The predominant fatty acids were iso-C17 : 0 3-OH, iso-C15 : 0, iso-C15 : 1 G, iso-C15 : 0 3-OH, iso-C16 : 0, iso-C17 : 1ω8c and summed feature 3. The polar lipid profile comprised phosphatidylethanolamine, three unidentified aminolipids and three unidentified lipids. The major respiratory quinone was MK-6. The genomic DNA G+C content was 32.6 mol%. On the basis of 16S rRNA gene sequence data, and chemotaxonomic and phenotypic characteristics, strain 9Alg 151T represents a novel species of the genus Aquimarina, for which the name Aquimarina algiphila sp. nov. is proposed. The type strain is 9Alg 151T (=KCTC 23622T=KMM 6462T).

Aquimarina rubra sp. nov., isolated from sediment of a sea cucumber culture pond.

A Gram-stain-negative, non-motile, rod-shaped, red-pigmented, facultatively anaerobic bacterium, designated SS2-9T, was isolated from sediment collected from a sea cucumber culture pond located in Rongcheng, Shandong province, China. Cells of strain SS2-9T were approximately 0.3-0.5 µm in width and 1.5-6.0 µm in length. The strain was able to grow at 10-37 °C, at pH 6.5-8.5 and in the presence of 0.5-6.0 % (w/v) NaCl. It grew optimally at 28 °C and in the presence of 2.0 % (w/v) NaCl. The DNA G+C content was 34.5 mol% and the sole respiratory quinone was menaquinone 6 (MK-6). The predominant cellular fatty acids were C15 : 0, iso-C15 : 1 G, iso-C15 : 0 and iso-C17 : 0 3-OH. The major polar lipids were phosphatidylethanolamine, an unidentified phospholipid, two unidentified aminolipids and four unidentified lipids. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain SS2-9T was phylogenetically related to members of the genus Aquimarina and was closely related to Aquimarina amphilecti 92VT (97.29 % similarity). On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain SS2-9T was considered to represent a novel species of the genus Aquimarina, for which the name Aquimarina rubra sp. nov. is proposed. The type strain is SS2-9T (=KCTC 52274T=MCCC 1H00142T).

Aquimarina seongsanensis sp. nov., isolated from sea water.

An orange, rod-shaped, gliding bacterium, designated strain CBA3208T, was isolated from sea water of Jeju Island, Republic of Korea. Cells were observed to be Gram-stain negative, strictly aerobic, catalase positive and oxidase negative and to hydrolyse starch, gelatin, and Tweens 40 and 80. The major fatty acids were identified as iso-C15:0, iso-C17:0 3-OH, and iso-C15:1 G. The only isoprenoid quinone was found to be menaquinone-6 (MK-6) and the major polar lipids were identified as phosphatidylethanolamine, two aminolipids and four unidentified polar lipids. The DNA G+C content of strain CBA3208T was determined to be 34.9mol%. Strain CBA3208T is considered to represent a novel species of the genus Aquimarina, for which the name Aquimarina seongsanensis sp. nov. is proposed based on this polyphasic taxonomic analysis. The type strain is CBA3208T (=KACC 17667T =JCM 19529T).

Aquimarina versatilis sp. nov., isolated from seashore sand, and emended description of the genus Aquimarina.

Strain CBA3207T, a novel Gram-stain-negative, aerobic and rod-shaped bacterium, was isolated from the seashore sand of Jeju island in South Korea. Strain CBA3207T grew optimally at 25-30 °C and pH 7.0-7.5 with 3.0-4.0 % (w/v) NaCl. It was catalase-positive, oxidase-negative, and hydrolysed starch, gelatin, and Tweens 20, 40 and 80. The 16S rRNA gene sequence of strain CBA3207T showed 96.0, 95.6, 95.6, 95.5 and 95.5 % similarity to that of Aquimarinamytili PSC33T, Aquimarinaagarivorans HQM9T, Aquimarinalatercula DSM 2041T, Aquimarinaintermedia KMM 6258T and Aquimarinaamphilecti 92VT, respectively. The major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 1 G and summed feature 9 (10-methyl C16 : 0 and/or iso-C17 : 1ω9c). The major respiratory quinone was menaquinone-6, and the major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and six unidentified lipids. The G+C content of the genomic DNA was 38.8 mol%. Based on phenotypic, genotypic and phylogenetic analyses, strain CBA3207T represents a novel species in the genus Aquimarina, for which the name Aquimarinaversatilissp. nov. is proposed. The type strain is CBA3207T (=KACC 17666T=JCM 19528T).

Aquimarina aggregata sp. nov., isolated from seawater.

A novel Gram-stain-negative, agarolytic, rod-shaped, non-flagellated, strictly aerobic strain with gliding motility, designated RZW4-3-2T, was isolated from coastal seawater of the Yellow Sea in China (119.625° E 35.517° N). The organism grew optimally at 28 °C, at pH 7.0 and in the presence of 2.0-3.0 % (w/v) NaCl. The strain required seawater or artificial seawater for growth, and NaCl alone did not support growth. Strain RZW4-3-2T contained MK-6 as the major respiratory quinone and iso-C17 : 0 3-OH, iso-C15 : 0, iso-C15 : 1 G and iso-C15 : 0 3-OH as the dominant fatty acids. The polar lipids of strain RZW4-3-2T comprised phosphatidylethanolamine, five unknown phospholipids and one unknown lipid. The DNA G+C content of strain RZW4-3-2T was 32.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the novel strain was related most closely to Aquimarina pacifica SW150T, Aquimarina macrocephali JCM 15542T and Aquimarina muelleri LMG 22569T with 98.1, 97.4 and 97.1 % sequence similarities, respectively. The estimated DNA-DNA hybridization values were 20.00±2.31 %, 20.70±2.33 % and 20.70±2.32 % between strain RZW4-3-2T and A. pacifica SW150T, A. macrocephali JCM 15542T and A. muelleri LMG 22569T, respectively. On the basis of results of polyphasic analyses, strain RZW4-3-2T represents a novel species of the genus Aquimarina, for which the name Aquimarinaaggregata sp. nov. is proposed. The type strain is RZW4-3-2T (=JCM 30824T=MCCC 1K00698T).

Aurantiacicella marina gen. nov., sp. nov., a myxol-producing bacterium from surface seawater.

A Gram-stain-negative, non-motile, mesophilic, aerobic, rod-shaped bacterium, strain 2A-8T, was isolated from surface seawater at Muroto city, Kochi prefecture, Japan. The strain produced myxol as a major carotenoid. Phylogenetic analyses based on 16S rRNA gene sequences showed that the strain fell within the family Flavobacteriaceae and was related most closely to the genus Aquimarina (91.0-94.4 % 16S rRNA gene sequence similarity to the type strains of species of this genus). The DNA G+C content was 35 mol%. The major fatty acids were iso-C15 : 0 and iso-C17 : 0 3-OH. The major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and five unidentified lipids. Menaquinone 6 was detected as the sole isoprenoid quinone. On the basis of phenotypic, genotypic and chemotaxonomic data, strain 2A-8T represents a novel genus and species, for which the name Aurantiacicella marina gen. nov., sp. nov. is proposed. The type strain of Aurantiacicella marina is 2A-8T ( = NBRC 111187T = KCTC 42676T).

Aquimarina hainanensis sp. nov., isolated from diseased Pacific white shrimp Litopenaeus vannamei larvae.

One novel Gram-stain-negative, long rod-shaped, non-spore-forming, non-motile, non-flagellated and strictly aerobic strain, designated M124T, was isolated from diseased Pacific white shrimp Litopenaeus vannamei larvae. Growth occurred at 16-37 °C (optimum 28 °C), in the presence of 2-5 % (w/v) NaCl (optimum 3 %) and at pH 7-8 (optimum pH 7). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain M124T belonged to the genus Aquimarina and showed highest sequence similarity to Aquimarina penaei P3-1T (96.4 %). The dominant fatty acids of the isolate were iso-C15 : 0 and iso-C17 : 0 3-OH. The major polar lipids comprised phosphatidylethanolamine, one unknown aminolipid, three unknown phospholipids, two unknown glycolipids and one unknown polar lipid. The major respiratory quinone was menaquinone 6 (MK-6). The DNA G+C content of strain M124T was 33.7 mol%. Based on the polyphasic analyses in this study, strain M124T is considered to represent a novel species of the genus Aquimarina, for which the name Aquimarina hainanensis sp. nov. is proposed. The type strain is M124T ( = KCTC 42423T = MCCC 1K00498T).

Aquimarina penaei sp. nov., isolated from intestinal tract contents of Pacific white shrimp, Penaeus vannamei.

A novel bacterial strain designated P3-1(T) was isolated from the intestinal tract contents of Pacific white shrimp (Penaeus vannamei) in Zhangpu, Fujian province, China. The isolate was found to be Gram-negative, long rod shaped, oxidase- and catalase- positive. Growth was observed at 1-7 % sea salt (w/v, optimum, 3 %), at pH 7.0-9.0 (optimum, pH 7.0) and at 10-37 °C (optimum, 28 °C). The isolate was capable of hydrolysing gelatin, casein, starch and DNA but unable to degrade Tween 20, 40, 80 and cellulose. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain P3-1(T) belongs to the genus Aquimarina, with highest sequence similarity to Aquimarina gracilis PSC32(T) (96.2 %), followed by Aquimarina intermedia KMM 6258(T) (96.1 %), Aquimarina spongiae A6(T) (95.9 %) and Aquimarina muelleri KMM 6020(T) (95.8 %). The principal cellular fatty acids were identified as iso-C15:0, iso-C17:0 3OH, C16:1 ω7c/ω6c, iso-C15:1 G, iso-C15:0 3OH, iso-C17:1 ω9c/C16:0 10-methyl and C16:0. The G+C content of the chromosomal DNA was determined to be 33.3 mol%. The respiratory quinone was determined to be MK-6 (100 %). The combined genotypic and phenotypic data show that strain P3-1(T) represents a novel species within the genus Aquimarina, for which the name Aquimarina penaei sp. nov. is proposed, with the type strain P3-1(T) (=MCCC 1A09871(T) = LMG 27943(T)).

Aquimarina atlantica sp. nov., isolated from surface seawater of the Atlantic Ocean.

A taxonomic study was carried out on strain 22II-S11-z7(T), which was isolated from the surface seawater of the Atlantic Ocean. The bacterium was found to be Gram-negative, oxidase negative and catalase positive, long-rod shaped, and gliding. Growth was observed at salinities of 1-5% and at temperatures of 10-41°C. The isolate was capable of hydrolysing gelatin and Tween 80 and able to reduce nitrate to nitrite, but unable to degrade aesculin. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 22II-S11-z7(T) belongs to the genus Aquimarina, with highest sequence similarity to Aquimarina megaterium XH134(T) (98.31%), followed by Aquimarina macrocephali JAMB N27(T) (96.59%); other species of the genus Aquimarina shared 93.63-96.08% sequence similarity. The ANI value between strain 22II-S11-z7(T) and A. megaterium XH134(T) was found to be 91.86-91.81%. The DNA-DNA hybridization estimated value between strain 22II-S11-z7(T) and A. megaterium XH134(T) was 47.7±2.6%. The principal fatty acids were identified as Summed Feature 3 (C16:1 ω7c/ω6c, as defined by the MIDI system; 8.1%), SummedFeature 9 (iso-C17:1 ω7c/C16:110-methyl; 6.8%), iso-C15:0 G (11.3%), iso-C15:0 (24.9%), iso-C16:0 (5.7%), C16:0 (5.2%), iso-C15:0 3OH (6.4%) and iso-C17:0 3OH (21.5%). The G+C content of the chromosomal DNA was determined to be 32.99mol%. The respiratory quinone was determined to be MK-6 (100%). Phosphatidylethanolamine, two unidentified aminolipids, five unidentified phospholipids and two unidentified lipids were found to be present. The combined genotypic and phenotypic data show that strain 22II-S11-z7(T) represents a novel species within the genus Aquimarina, for which the name Aquimarina atlantica sp. nov. is proposed, with the type strain 22II-S11-z7(T) (=MCCC 1A09239(T)=KCTC 42003(T)).

Molecular richness and biotechnological potential of bacteria cultured from Irciniidae sponges in the north-east Atlantic

Several bioactive compounds originally isolated from marine sponges have been later ascribed or suggested to be synthesized by their symbionts. The cultivation of sponge-associated bacteria provides one possible route to the discovery of these metabolites. Here, we determine the bacterial richness cultured from two irciniid sponge species, Sarcotragus spinosulus and Ircinia variabilis, and ascertain their biotechnological potential. A total of 279 isolates were identified from 13 sponge specimens. These were classified into 17 genera - with Pseudovibrio, Ruegeria and Vibrio as the most dominant - and 3 to 10 putatively new bacterial species. While 16S rRNA gene sequencing identified 29 bacterial phylotypes at the 'species' level (97% sequence similarity), whole-genome BOX-PCR fingerprinting uncovered 155 genotypes, unveiling patterns of specimen-dependent occurrence of prevailing bacterial genomes across sponge individuals. Among the BOX-PCR genotypes recovered, 34% were active against clinically relevant strains, with Vibrio isolates producing the most active antagonistic effect. Several Pseudovibrio genotypes showed the presence of polyketide synthase (PKS) genes, and these were for the first time detected in isolates of the genus Aquimarina (Bacteroidetes). Our results highlight great biotechnological potential and interest for the Irciniidae sponge family and their diversified bacterial genomes.

Dysbiosis in Epizootic Shell Disease of the American Lobster (Homarus americanus)

Epizootic shell disease (ESD) in the American lobster (Homarus americanus) is continuing to affect the southern New England lobster population, and the etiology of the disease has not been well defined. We hypothesized that a dysbiotic shift in the shell microbial biofilm played a key part in the etiology of the disease. We analyzed the community structure of the surface microflora of apparently healthy and diseased lobsters using multitag pyrosequencing to correlate the abundance of key taxa within the lesions. Discriminant analysis (DA) was used to identify taxa in the microbial community that were associated with diseased and healthy states. Among the 170 bacterial taxa that were identified, 58 were helpful in determining the diseased and healthy states. The remaining 112 were not significantly different between the 2 states. The genus Aquimarina was present in high abundance in both healthy and diseased lobsters, but had a significantly higher abundance on animals in the diseased state. However, DA demonstrated that this genus does not strongly discriminate between the diseased and healthy state. Phylogenetic analysis indicated that there was significant strain diversity of this genus in all the samples analyzed. Our results indicate that the lesions seen in ESD may be viewed as being correlated with a polymicrobial component rather than being caused by a discrete pathogen.