Colwellia maritima sp. nov. and Polaribacter marinus sp. nov., isolated from seawater

Two Gram-stain-negative, catalase- and oxidase-positive, and aerobic bacteria, strains MSW7^T and MSW13^T, were isolated from seawater. Cells of strains MSW7^T and MSW13^T are motile and non-motile rods, respectively. Strain MSW7^T optimally grew at 25 °C and pH 7.0 and in the presence of 3 % (w/v) NaCl, whereas strain MSW13^T optimally grew at 25 °C and pH 6.0-7.0 and in the presence of 2 % NaCl. As the sole respiratory quinone and the major fatty acids and polar lipids, strain MSW7^T contained ubiquinone-8, C_16 : 0, C_15 : 1  ω8c, C_17 : 1  ω8c and summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), and phosphatidylethanolamine and phosphatidylglycerol, respectively, whereas strain MSW13^T contained menaquinone-6, C_15 : 1  ω6c, iso-C_15 : 0, anteiso-C_15 : 0, and iso-C_15 : 0 3-OH, and phosphatidylethanolamine, respectively. The DNA G+C contents of strains MSW7^T and MSW13^T were 37.3 and 29.9 %, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains MSW7^T and MSW13^T were most closely related to Colwellia echini A3^T and Polaribacter atrinae WP25^T with 98.8 and 98.1 % sequence similarities, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between strain MSW7^T and C. echini A3^T and between strain MSW13^T and P. atrinae KACC 17473^T were 73.6 and 22.6 % and 80.4 and 23.8 %, respectively. Based on phenotypic, chemotaxonomic and phylogenetic data, strains MSW7^T and MSW13^T represent novel species of the genera Colwellia and Polaribacter, respectively, for which the names Colwellia maritima sp. nov. and Polaribacter marinus sp. nov. are proposed, respectively. The type strains of C. maritima sp. nov. and P. marinus sp. nov. are MSW7^T (=KACC 22339^T=JCM 35001^T) and MSW13^T (=KACC 22341^T=JCM 35021^T), respectively.

A Review of Asteroid Biology in the Context of Sea Star Wasting: Possible Causes and Consequences

AbstractSea star wasting-marked in a variety of sea star species as varying degrees of skin lesions followed by disintegration-recently caused one of the largest marine die-offs ever recorded on the west coast of North America, killing billions of sea stars. Despite the important ramifications this mortality had for coastal benthic ecosystems, such as increased abundance of prey, little is known about the causes of the disease or the mechanisms of its progression. Although there have been studies indicating a range of causal mechanisms, including viruses and environmental effects, the broad spatial and depth range of affected populations leaves many questions remaining about either infectious or non-infectious mechanisms. Wasting appears to start with degradation of mutable connective tissue in the body wall, leading to disintegration of the epidermis. Here, we briefly review basic sea star biology in the context of sea star wasting and present our current knowledge and hypotheses related to the symptoms, the microbiome, the viruses, and the associated environmental stressors. We also highlight throughout the article knowledge gaps and the data needed to better understand sea star wasting mechanistically, its causes, and potential management.

Effects of microbial community and disease resistance against Vibrio splendidus of Yesso scallop (Patinopecten yessoensis) fed supplementary diets of tussah immunoreactive substances and antimicrobial peptides

This study was conducted to investigate the effects of dietary supplementation of tussah immunoreactive substances (TIS) and antimicrobial peptides (AMPs) on microbial community and resistance against Vibrio splendidus of Yesso scallop Patinopecten yessoensis. Scallops were fed with the basal diets supplemented with TIS (T group), AMPs (A group), or both of the two (TA group). After the feeding trial, the microbial community changes were evaluated, and the challenge test with V. splendidus was conducted, as well as the immune parameters and digestive enzyme activities were determined. The results revealed that the TA group was more capable of modulating the bacterial community composition of scallops by increasing the potentially beneficial bacteria and suppressing the pathogenic microorganism during the feeding trial. After injection, the cumulative mortality rate in TA group was notably lower than others. In addition, the TA group showed better digestive and immune parameters involved in digestive capacity, phagocyte function, phosphatase-responsiveness, and oxidation resistance. These results collectively confirmed that dietary TIS and AMPs in diet could effectively modulate the microflora structure and improve disease resistance against V. splendidus of scallop, and the positive effects were more obvious when dietary supplementation of them in combination.

Colwellia ponticola sp. nov., isolated from seawater

A Gram-stain-negative, aerobic, motile and rod-shaped bacterial strain, designated OISW-25^T, was isolated from seawater in Republic of Korea. Strain OISW-25^T grew optimally at 25 °C and in the presence of 2.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain OISW-25^T fell within the clade comprising the type strains of Colwellia species. Strain OISW-25^T exhibited 16S rRNA gene sequence similarity values of 97.5, 97.2 and 97.1 % to the type strains of C. piezophila, C. maris and C. psychrerythraea, respectively, and of 93.6-96.6 % to the type strains of the other Colwellia species. The average nucleotide identity values between strain OISW-25^T and C. piezophila ATCC BAA-637^T and two non-type strains of C. psychrerythraea were 78.16-79.35 % and DNA-DNA relatedness value of strain OISW-25^T with the type strain of C. maris was 17 %. The DNA G+C content of strain OISW-25^T was 39.2 mol% (HPLC) or 38.7 mol% (genome data). Strain OISW-25^T contained Q-8 as the predominant ubiquinone and summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c) and C_16 : 0 as the major fatty acids. The major polar lipids of strain OISW-25^T were phosphatidylethanolamine and phosphatidylglycerol. Distinguished phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that strain OISW-25^T is distinct from Colwellia species. On the basis of the data presented, strain OISW-25^T is considered to represent a novel species of the genus Colwellia, for which the name Colwellia ponticola sp. nov. is proposed. The type strain is OISW-25^T (=KCTC 62426^T=NBRC 113187^T).

Bacterial biofilm development during experimental degradation of Melicertus kerathurus exoskeleton in seawater

Chitinolytic bacteria are widespread in marine and terrestrial environment, and this is rather a reflection of their principle growth substrate's ubiquity, chitin, in our planet. In this paper, we investigated the development of naturally occurring bacterial biofilms on the exoskeleton of the shrimp Melicertus kerathurus during its degradation in sea water. During a 12-day experiment with exoskeleton fragments in batch cultures containing only sea water as the growth medium at 18 °C in darkness, we analysed the formation and succession of biofilms by scanning electron microscopy and 16S rRNA gene diversity by next generation sequencing. Bacteria belonging to the γ- and α-Proteobacteria and Bacteroidetes showed marked (less or more than 10%) changes in their relative abundance from the beginning of the experiment. These bacterial taxa related to known chitinolytic bacteria were the Pseudolateromonas porphyrae, Halomonasaquamarina, Reinekea aestuarii, Colwellia asteriadis and Vibrio crassostreae. These bacteria could be considered as appropriate candidates for the degradation of chitinous crustacean waste from the seafood industry as they dominated in the biofilms developed on the shrimp's exoskeleton in natural sea water with no added substrates and the degradation of the shrimp exoskeleton was also evidenced.

Colwellia echini sp. nov., an agar- and carrageenan-solubilizing bacterium isolated from sea urchin

A novel bacterial strain, A3^T, was isolated from the intestines of the sea urchin Strongylocentrotus droebachiensis collected in Øresund, Denmark. The strain was Gram-reaction-negative, rod-shaped and facultatively anaerobic, and displayed growth at 5-25 °C (optimum 20 °C), pH 7-9 (optimum at pH 7) and 1-6 % (w/v) NaCl (optimum 3 %). Furthermore, strain A3^T grew on agar, agarose, κ-carrageenan, alginate and laminarin as sole carbon source. Complete liquefaction of agar and κ-carrageenan was observed on solid plate media as a result of enzymatic activities. Major fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The respiratory quinones were determined to be ubiquinones Q-8 (92 %) and Q-7 (8 %), and polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The DNA G+C content was 36.9 mol%. Phylogenetical analyses based on the 16S rRNA gene showed that the bacterium was affiliated with the genus Colwellia within the Alteromonadaceae of the Gammaproteobacteria. The level of 16S rRNA gene sequence similarity between strain A3^T and its closest relatives in the genus Colwellia (C. psychrerythraea ATCC 27364^T and C. asteriadis KMD 002^T) was 97.5 %. The average nucleotide identity between strain A3^T and other members of Colwellia was 78.6-80.5 %, and DNA-DNA hybridization prediction revealed values of less than 23 % relatedness between strain A3^T and other Colwellia species. The phenotypic, phylogenetic and genomic analyses support the hypothesis that strain A3^T represents a novel species of the genus Colwellia, for which the name Colwellia echini sp. nov. is proposed. The type strain is A3^T (=LMG 30125^T=NCIMB 15095^T).

Colwellia mytili sp. nov., isolated from mussel Mytilus edulis

A Gram-stain-negative, aerobic, motile and rod-shaped bacterial strain, designated RA2-7T, was isolated from a mussel (Mytilus edulis) collected from the South Sea, South Korea, and subjected to a taxonomic study using a polyphasic approach. Strain RA2-7T grew optimally at 20 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain RA2-7T belonged to the genus Colwellia. Strain RA2-7T exhibited 16S rRNA gene sequence similarity values of 98.3, 98.0 and 97.5 % to the type strains of Colwellia sediminilitoris, Colwellia aestuarii and Colwellia polaris, respectively, and of 94.5-96.5 % to the type strains of the other species of the genus Colwellia. Strain RA2-7T contained Q-8 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0 as the major fatty acids. The major polar lipids detected in strain RA2-7T were phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain RA2-7T was 39.0±0.04 mol% and its DNA-DNA relatedness values with the type strains of C. sediminilitoris, C. aestuarii and C. polaris were 14-19 %. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain RA2-7T is separated from recognized species of the genus Colwellia. On the basis of the data presented, strain RA2-7T is considered to represent a novel species of the genus Colwellia, for which the name Colwellia mytili sp. nov. is proposed. The type strain is RA2-7T (=KCTC 52417T=NBRC 112381T).

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

A Gram-stain-negative, aerobic, motile and rod-shaped or ovoid bacterial strain, designated YSM-23T, was isolated from a tidal flat on the South Sea in South Korea, and subjected to a polyphasic taxonomic study. Strain YSM-23T grew optimally at 30 °C, at pH 7.0-8.0 and in the presence of 1.0-2.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain YSM-23T represented a member of the genus Colwellia. Strain YSM-23T exhibited 16S rRNA gene sequence similarity values of 98.0, 97.4 and 97.3 % to the type strains of Colwellia aestuarii, Colwellia polaris and Colwellia chukchiensis, respectively, and of 94.5-96.8 % to the type strains of the other species of the genus Colwellia. Strain YSM-23T contained Q-8 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) as the major fatty acid. The major polar lipids detected in strain YSM-23T were phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain YSM-23T was 43.8±0.08 mol% and its DNA-DNA relatedness values with the type strain of C. aestuarii, C. polaris and C. chukchiensis were 10±3.5-22±4.9 %. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain YSM-23T is separated from species of the genus Colwelliawith validly published names. On the basis of the data presented, strain YSM-23T is considered to represent a novel species of the genus Colwellia, for which the name Colwellia sediminilitoris sp. nov. is proposed. The type strain is YSM-23T (=KCTC 52213T=NBRC 111994T).

Identification of Associations between Bacterioplankton and Photosynthetic Picoeukaryotes in Coastal Waters

Photosynthetic picoeukaryotes are significant contributors to marine primary productivity. Associations between marine bacterioplankton and picoeukaryotes frequently occur and can have large biogeochemical impacts. We used flow cytometry to sort cells from seawater to identify non-eukaryotic phylotypes that are associated with photosynthetic picoeukaryotes. Samples were collected at the Santa Cruz wharf on Monterey Bay, CA, USA during summer and fall, 2014. The phylogeny of associated microbes was assessed through 16S rRNA gene amplicon clone and Illumina MiSeq libraries. The most frequently detected bacterioplankton phyla within the photosynthetic picoeukaryote sorts were Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) and Bacteroidetes. Intriguingly, the presence of free-living bacterial genera in the photosynthetic picoeukaryote sorts could suggest that some of the photosynthetic picoeukaryotes were mixotrophs. However, the occurrence of bacterial sequences, which were not prevalent in the corresponding bulk seawater samples, indicates that there was also a selection for specific OTUs in association with photosynthetic picoeukaryotes suggesting specific functional associations. The results show that diverse bacterial phylotypes are found in association with photosynthetic picoeukaryotes. Taxonomic identification of these associations is a prerequisite for further characterizing and to elucidate their metabolic pathways and ecological functions.

Colwellia aquaemaris sp. nov., isolated from the Cynoglossus semilaevis culture tank in a recirculating mariculture system

A Gram-staining-negative, heterotrophic, facultatively anaerobic bacterium, designated S1T, was isolated from the Cynoglossus semilaevis culture pond in a recirculating mariculture system in Tianjin, China. The taxonomy of strain S1T was studied by using a polyphasic approach. Cells of strain S1T were non-spore-forming, curved rods, 0.4–0.6 µm wide and 1.2–2.0 µm long, and motile by means of a single polar flagellum. The strain was positive for oxidase and catalase activities. Strain S1T was able to grow at 4–30 °C (optimum, 25 °C), at pH 5.5–10.0 (optimum, pH 6.5–7.5) and in the presence of 1–5 % (w/v) NaCl (optimum, 2 %). Strain S1T contained Q-8 as the sole respiratory quinone and C16 : 1ω7c/C16 : 1ω6c and C16 : 0 as the predominant cellular fatty acids. The genomic DNA G+C content was 40.1 mol% (T m). Phylogenetic analysis based on 16S rRNA gene sequences placed strain S1T in the genus Colwellia , and it formed a distinct lineage in the phylogenetic tree together with Colwellia meonggei MA1-3T, Colwellia aestuarii SMK-10T, Colwellia polaris 537T and Colwellia chukchiensis BCw111T, with 97.7, 96.1, 95.9 and 95.0 % 16S rRNA gene sequence similarity to these strains, respectively. DNA–DNA relatedness of strain S1T to Colwellia meonggei MA1-3T was 23.5±3.6 %. On the basis of the phylogenetic and phenotypic evidence, strain S1T is considered to represent a novel species of the genus Colwellia , for which the name Colwellia aquaemaris sp. nov. is proposed. The type strain is S1T ( = CGMCC 1.12165T = JCM 18479T).

Microbial life in a fjord: metagenomic analysis of a microbial mat in Chilean patagonia

The current study describes the taxonomic and functional composition of metagenomic sequences obtained from a filamentous microbial mat isolated from the Comau fjord, located in the northernmost part of the Chilean Patagonia. The taxonomic composition of the microbial community showed a high proportion of members of the Gammaproteobacteria, including a high number of sequences that were recruited to the genomes of Moritella marina MP-1 and Colwelliapsycherythraea 34H, suggesting the presence of populations related to these two psychrophilic bacterial species. Functional analysis of the community indicated a high proportion of genes coding for the transport and metabolism of amino acids, as well as in energy production. Among the energy production functions, we found protein-coding genes for sulfate and nitrate reduction, both processes associated with Gammaproteobacteria-related sequences. This report provides the first examination of the taxonomic composition and genetic diversity associated with these conspicuous microbial mat communities and provides a framework for future microbial studies in the Comau fjord.

Neiella marina gen. nov., sp. nov., isolated from the sea cucumber Apostichopus japonicus

A novel strain, designated J221(T), was isolated from the intestine of a sea cucumber, Apostichopus japonicus, collected from earthen ponds in Qingdao, China. The strain was Gram-negative, oxidase-positive, aerobic, rod-shaped and motile by means of one to several polar flagella. Growth of strain J221(T) was observed at temperatures between 10 and 40 °C with optimum growth between 25 and 28 °C. The pH range for growth was 5.0-9.0 with optimum growth at pH 7.5-8.0. The dominant fatty acids were summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c, 29.04 %), C16 : 0 (28.93 %) and C18 : 1ω7c (26.15 %). The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. Diphosphatidylglycerol, an unknown aminolipid and an unknown aminophospholipid were present in moderate to minor amounts in the polar lipid profile. Strain J221(T) had Q-8 as the major respiratory quinone. The DNA G+C content of strain J221(T) was 46.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain J221(T) is a member of the Gammaproteobacteria. It formed a distinct phyletic line with less than 91 % sequence similarity to any species within previously recognized genera. On the basis of this polyphasic taxonomic study, strain J221(T) should be classified as a representative of a novel species of a new genus, for which the name Neiella marina gen. nov., sp. nov. is proposed. The type strain of Neiella marina is J221(T) ( = CGMCC 1.10130(T) = NRRL B-51319(T)).

Colwellia chukchiensis sp. nov., a psychrotolerant bacterium isolated from the Arctic Ocean

A novel psychrotolerant bacterial strain, BCw111(T), was isolated from seawater samples from the Chukchi Sea in the Arctic Ocean. Cells of strain BCw111(T) were Gram-negative, motile, facultatively anaerobic, curved rods and were able to grow at 0-30 °C (optimum 23-25 °C). Strain BCw111(T) had Q-8 as the major respiratory quinone and contained iso-C(15 : 0) 2-OH and/or C(16 : 1)ω7c (28.13 %), C(16 : 0) (13.28 %) and C(17 : 1) (12.90 %) as the major cellular fatty acids. The genomic DNA G+C content was 41.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BCw11(T) formed a distinct lineage within the genus Colwellia and exhibited the highest 16S rRNA gene sequence similarity with Colwellia polaris 537(T) (97.8 %) and Colwellia aestuarii SMK-10(T) (97.1 %). Based on phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness, a novel species, Colwellia chukchiensis sp. nov., is proposed. The type strain is BCw111(T) ( = CGMCC 1.9127(T)  = LMG 25329(T)  = DSM 22576(T)).