Thalassospira aquimaris sp. nov. and Winogradskyella marincola sp. nov. two marine bacteria isolated from an agar-degrading co-culture.

Two novel Gram-stain-negative, aerobic, and non-motile strains, designated FZY0004T and YYF002T, were isolated from an agar-degrading co-culture, which was obtained from seawater of the intertidal zone of Yancheng City, the Yellow Sea of China. Strain FZY0004T optimally grew at 28 °C, pH 7.0, and 2-6% NaCl, while strain YYF002T optimally grew at 28 °C, pH 7.5, and 2-4% NaCl. Strain FZY0004T possessed Q-9 as the major respiratory quinone, and its major fatty acids (> 10%) were summed feature 8 (C18:1 ω7c), C16:0, and summed feature 3 (C16:1 ω7c/C16:1 ω6c). The polar lipids identified in strain FZY0004T were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and several unidentified phospholipids (PL) and lipids (L). On the other hand, strain YYF002T had MK-6 as the predominant respiratory quinone and its major fatty acids consisted of iso-C15:0, iso-C15:1 G, and iso-C15:0 3-OH. The polar lipids identified in strain YYF002T were aminolipid (AL), PE, and several unidentified lipids. Strain FZY0004T shared 99.5% 16S rRNA gene sequence similarity and 90.1% average nucleotide identity (ANI) with T. povalilytica Zumi 95T, and strain YYF002T shared 99.2% 16S rRNA gene sequence similarity and 88.2% ANI with W. poriferorum JCM 12885T. The genomic DNA G + C contents of strains FZY0004T and YYF002T were 54.5% and 33.5%, respectively. The phylogenetic, phenotypic, and physiological characteristics permitted the distinction of the two strains from their neighbors, and we thus propose the names Thalassospira aquimaris sp. nov. (type strain FZY0004T = JCM 35895T = MCCC 1K08380T) and Winogradskyella marincola sp. nov. (type strain YYF002T = JCM 35950T = MCCC 1K08382T).

Biodegradation of aliphatic and aromatic hydrocarbons by bacteria isolated from Bahregan area.

Environmental pollution with aromatic and aliphatic hydrocarbons caused by oil and petrochemical industries has very toxic and carcinogenic effects on living organisms and should be removed from the environment. In this research, after analyzing the oil sludge of the Bahregan area, it was found that most aliphatic paraffin compounds are related to octadecane, most liquid aliphatic compounds are related to hexadecane, and most aromatic compounds are related to naphthalene, phenanthrene, fluoranthene, and anthracene. Then, we investigated the ability of native bacteria from this area, such as Thalassospira, Chromohalobacter, and a bacterial consortium, to biodegrade the dominant aromatic and aliphatic hydrocarbons found in oil sludge. The results of Gas Chromatography-Mass Spectrometry analysis showed that among the tested hydrocarbon sources, Thalassospira can completely remove octadecane and hexadecane, and Chromohalobacter can reduce hexadecane from 15.9 to 9.9%. The bacterial consortium can completely remove octadecane and reduce hexadecane from 15.9 to 5.1%, toluene from 25.6 to 0.6%, and phenanthrene from 12.93 to 6%. According to the obtained results, the bacterial consortium effectively plays a role in the biodegradation of aromatic and aliphatic hydrocarbons, making it a viable solution for treating hydrocarbon pollutants in various environments.

Bacterial Community Shifts during Polyp Bail-Out Induction in Pocillopora Corals.

Polyp bail-out constitutes both a stress response and an asexual reproductive strategy that potentially facilitates dispersal of some scleractinian corals, including several dominant reef-building taxa in the family Pocilloporidae. Recent studies have proposed that microorganisms may be involved in onset and progression of polyp bail-out. However, changes in the coral microbiome during polyp bail-out have not been investigated. In this study, we induced polyp bail-out in Pocillopora corals using hypersaline and hyperthermal methods. Bacterial community dynamics during bail-out induction were examined using the V5-V6 region of the 16S-rRNA gene. From 70 16S-rRNA gene libraries constructed from coral tissues, 1,980 OTUs were identified. Gammaproteobacteria and Alphaproteobacteria consistently constituted the dominant bacterial taxa in all coral tissue samples. Onset of polyp bail-out was characterized by increased relative abundance of Alphaproteobacteria and decreased abundance of Gammaproteobacteria in both induction experiments, with the shift being more prominent in response to elevated temperature than to elevated salinity. Four OTUs, affiliated with Thalassospira, Marisediminitalea, Rhodobacteraceae, and Myxococcales, showed concurrent abundance increases at the onset of polyp bail-out in both experiments, suggesting potential microbial causes of this coral stress response. IMPORTANCE Polyp bail-out represents both a stress response and an asexual reproductive strategy with significant implications for reshaping tropical coral reefs in response to global climate change. Although earlier studies have suggested that coral-associated microbiomes likely contribute to initiation of polyp bail-out in scleractinian corals, there have been no studies of coral microbiome shifts during polyp bail-out. In this study, we present the first investigation of changes in bacterial symbionts during two experiments in which polyp bail-out was induced by different environmental stressors. These results provide a background of coral microbiome dynamics during polyp bail-out development. Increases in abundance of Thalassospira, Marisediminitalea, Rhodobacteraceae, and Myxococcales that occurred in both experiments suggest that these bacteria are potential microbial causes of polyp bail-out, shedding light on the proximal triggering mechanism of this coral stress response.

Environmental and Taxonomic Drivers of Bacterial Extracellular Vesicle Production in Marine Ecosystems.

Extracellular vesicles are small (approximately 50 to 250 nm in diameter), membrane-bound structures that are released by cells into their surrounding environment. Heterogeneous populations of vesicles are abundant in the global oceans, and they likely play a number of ecological roles in these microbially dominated ecosystems. Here, we examine how vesicle production and size vary among different strains of cultivated marine microbes as well as explore the degree to which this is influenced by key environmental variables. We show that both vesicle production rates and vesicle sizes significantly differ among cultures of marine Proteobacteria, Cyanobacteria, and Bacteroidetes. Further, these properties vary within individual strains as a function of differences in environmental conditions, such as nutrients, temperature, and light irradiance. Thus, both community composition and the local abiotic environment are expected to modulate the production and standing stock of vesicles in the oceans. Examining samples from the oligotrophic North Pacific Gyre, we show depth-dependent changes in the abundance of vesicle-like particles in the upper water column in a manner that is broadly consistent with culture observations: the highest vesicle abundances are found near the surface, where the light irradiances and the temperatures are the greatest, and they then decrease with depth. This work represents the beginnings of a quantitative framework for describing extracellular vesicle dynamics in the oceans, which is essential as we begin to incorporate vesicles into our ecological and biogeochemical understanding of marine ecosystems. IMPORTANCE Bacteria release extracellular vesicles that contain a wide variety of cellular compounds, including lipids, proteins, nucleic acids, and small molecules, into their surrounding environment. These structures are found in diverse microbial habitats, including the oceans, where their distributions vary throughout the water column and likely affect their functional impacts within microbial ecosystems. Using a quantitative analysis of marine microbial cultures, we show that bacterial vesicle production in the oceans is shaped by a combination of biotic and abiotic factors. Different marine taxa release vesicles at rates that vary across an order of magnitude, and vesicle production changes dynamically as a function of environmental conditions. These findings represent a step forward in our understanding of bacterial extracellular vesicle production dynamics and provide a basis for the quantitative exploration of the factors that shape vesicle dynamics in natural ecosystems.

Identification and implications of a core bacterial microbiome in 19 clonal cultures laboratory-reared for months to years of the cosmopolitan dinoflagellate Karlodinium veneficum.

Identification of a core microbiome (a group of taxa commonly present and consistently abundant in most samples of host populations) is important to capture the key microbes closely associated with a host population, as this process may potentially contribute to further revealing their spatial distribution, temporal stability, ecological influence, and even impacts on their host's functions and fitness. The naked dinoflagellate Karlodinium veneficum is a cosmopolitan and toxic species, which is also notorious in forming harmful algal blooms (HABs) and causing massive fish-kills. Here we reported the core microbiome tightly associated with 19 strains of K. veneficum that were originally isolated from 6 geographic locations along the coast of China and from an estuary of Chesapeake Bay, United States, and have been maintained in the laboratory for several months to over 14 years. Using high-throughput metabarcoding of the partial 16S rRNA gene amplicons, a total of 1,417 prokaryotic features were detected in the entire bacterial microbiome, which were assigned to 17 phyla, 35 classes, 90 orders, 273 families, and 716 genera. Although the bacterial communities associated with K. veneficum cultures displayed heterogeneity in feature (sequences clustered at 100% sequence similarity) composition among strains, a core set of 6 genera were found persistent in their phycospheres, which could contribute up to 74.54% of the whole bacterial microbiome. Three γ-proteobacteria members of the "core," namely, Alteromonas, Marinobacter, and Methylophaga, were the predominant core genera and made up 83.25% of the core bacterial microbiome. The other 3 core genera, Alcanivorax, Thalassospira, and Ponticoccus, are reported to preferably utilize hydrocarbons as sole or major source of carbon and energy, and two of which (Alcanivorax and Ponticoccus) are recognized as obligate hydrocarbonoclastic bacteria (OHCB). Since OHCB generally present in extremely low abundance in marine water and elevate their abundance mostly in petroleum-impacted water, our detection in K. veneficum cultures suggests that the occurrence of obligate and generalist hydrocarbon-degrading bacteria living with dinoflagellates may be more frequent in nature. Our work identified a core microbiome with stable association with the harmful alga K. veneficum and opened a window for further characterization of the physiological mechanisms and ecological implications for the dinoflagellate-bacteria association.

Genomic analysis of Thalassospira sp. SW-3-3 reveals its genetic potential for phthalate pollution remediation.

Thalassospira sp. SW-3-3 is a bacterial strain isolated from deep seawater of the Pacific Ocean at a water depth of 3112 m. It is a Gram-negative, aerobic, and curved rod-shaped bacterium belonging to the family Thalassospiraceae. In this study, we report the complete genome sequence of strain SW-3-3. It has a circular chromosome with a size of 4,764,478 bp and a G + C content of 54.7%. The genome contains 4296 protein-coding genes, 63 tRNA genes, and 12 rRNA genes. Genomic analysis shows that strain SW-3-3 contains genes and catalytic pathways relevant to phthalate metabolism. Phthalates are well-known emerging contaminants that are harmful to environments and human health. They are chemically stable compounds that are widely used in plastic products and are pervasive in our life. With the discharge of plastic pollutants, a huge number of phthalate compounds enter the ocean. The genetic information of strain SW-3-3 suggests that it has the potential to metabolize phthalates. There are 9 key enzymes in the metabolization pathway, and phthalates are finally catalyzed to produce succinyl-CoA which is further degraded through the tricarboxylic acid (TCA) cycle pathway. This genomic analysis will be helpful for further understanding of the applications of strain SW-3-3 in the remediation of phthalate pollution.

Endocarditis caused by Thalassospira sp.

We report a case of an infective endocarditis caused by a Thalassospira sp. in a 53-year-old man with pre-existing valvular lesions and living in French Polynesia as a fisherman. The strain was identified with DNA-sequecing methods while it was not by mass spectrometry.

Thalassospira marina sp. nov., isolated from surface seawater.

Two novel marine bacteria, designated strains CSC3H3T and CSC1P2, were isolated from surface seawater of the South China Sea. Both strains were Gram-negative, oxidase-positive, catalase-positive, curved rods and motile. They grew at 10-40 °C, pH 5-10 and in the presence of 0-15 % (w/v) NaCl. Their 16S rRNA gene sequences were identical to each other. Phylogenetic analysis based on 16S rRNA gene sequences indicated that they belong to the genus Thalassospira, and shared 97.5-98.3 % sequence similarity to all other validly type strains of the genus Thalassospira, and the highest similarity was to the type strain Thalassospira povalilyticaZumi 95T (98.3 %), followed by Thalassospira australica NP3b2T (98.2 %). The digital DNA-DNA hybridization value between the two strains was 80.4 %, while the values with T. povalilyticaZumi 95T and T. australica NP3b2T were only 20.5-20.7 % and 20.4-20.5 %, respectively. The two strains possess similar major cellular fatty acids including C18 : 1ω7c, C16 : 0, C19 : 0ω8c cyclo, C18 : 1 2-OH and C17 : 0 cyclo. The G+C contents of the chromosomal DNA of strains CSC3H3T and CSC1P2 were 54.6 and 54.5 mol%, respectively. The major respiratory quinone was ubiquinone 10. Phosphatidylethanolamine, phosphatidylglycerol and several unidentified phospholipids, aminolipid and lipids were present in both strains. Based on phenotypic and genotypic characteristics, the two strains represent a novel species within the genus Thalassospira, for which the name Thalassospira marina sp. nov. is proposed. The type strain is CSC3H3T (=MCCC 1A11786T=KCTC 62333T).

Enhanced Production of κ-Carrageenase and κ-Carrageenan Oligosaccharides through Immobilization of Thalassospira sp. Fjfst-332 with Magnetic Fe3O4-Chitosan Microspheres.

In this study, immobilized bacteria (IMB) microsphere was prepared by embedding κ-carrageenase-producing Thalassospira sp. Fjfst-332 (TF332) onto a magnetic Fe3O4-chitosan carrier. The performance of Fe3O4-chitosan carrier was optimized by comparing its bacteria immobilization capacity at different Fe3O4:chitosan ratios and temperatures, while the functions of IMB microspheres were characterized by examining their κ-carrageenase production at different temperatures, pH's, and reuse cycles. At the 1:1 (w:w) Fe3O4:chitosan ratio, the Fe3O4-chitosan carriers possessed sufficient anchoring capacity for bacterial immobilization without significant compromise of their magnetism for magnetic separation of IMB from culture media. The spectroscopic analysis of IMB microspheres indicated that the immobilization of TF332 might affect the amide groups in chitosan. Compared to free bacteria, IMB can produce κ-carrageenase at higher temperature, wider pH range, and faster rate. More importantly, the κ-carrageenase-producing activity was sustained for at least seven reuse cycles. The major κ-carrageenan degradation products of IMB-derived κ-carrageenase were the oligosaccharides containing two to six monosaccharide units. Overall, this Fe3O4-chitosan-TF-332 microsphere has the potential to become a stable and reusable platform for large-scale production of κ-carrageenan oligosaccharides.

Medium Optimization and Fermentation Kinetics for κ-Carrageenase Production by Thalassospira sp. Fjfst-332.

Effective degradation of κ-carrageenan by isolated Thalassospira sp. fjfst-332 is reported for the first time in this paper. It was identified by 16S rDNA sequencing and morphological observation using Transmission Electron Microscopy (TEM). Based on a Plackett-Burman design for significant variables, Box-Behnken experimental design and response surface methodology were used to optimize the culture conditions. Through statistical optimization, the optimum medium components were determined as follows: 2.0 g/L κ-carrageenan, 1.0 g/L yeast extract, 1.0 g/L FOS, 20.0 g/L NaCl, 2.0 g/L NaNO3, 0.5 g/L MgSO4·7H2O, 0.1 g/L K2HPO4, and 0.1 g/L CaCl2. The highest activity exhibited by Thalassospira sp. fjfst-332 was 267 U/mL, which makes it the most vigorous wild bacterium for κ-carrageenan production. In order to guide scaled-up production, two empirical models-the logistic equation and Luedeking-Piretequation-were proposed to predict the strain growth and enzyme production, respectively. Furthermore, we report the fermentation kinetics and every empirical equation of the coefficients (α, ß, X0, Xm and µm) for the two models, which could be used to design and optimize industrial processes.

Preliminary characterization of a novel ß-agarase from Thalassospira profundimonas.

BACKGROUND: The objective of this study was to characterize the agarase from a newly isolated agarolytic bacterium Thalassospira profundimaris fst-13007. RESULTS: Agarase-fst was purified to homogeneity which apparent molecular weight was 66.2 kDa. Its activity was optimal at 45 °C and pH 8 and was stable at pH 5-9 or 30-50 °C. Agarase-fst required Mn(2+) for agarase activity and inhibition by Cu(2+), Fe(3+) and EDTA. Tests of hydrolysis pattern and substrate specificity, TLC analysis and mass spectrometry of the hydrolysis products revealed that it is an endo-type ß-agarase hydrolyzing agarose into neoagarobiose, neoagarotetraose and neoagarohexaose. Results of MALDI-TOF-TOF/MS indicate that it lack of homology to previously identified proteins and present conserved domain of ß-agarase. CONCLUSION: Agarase-fst from T. profundimaris fst-13007 was confirmed to be a novel endo-type ß-agarase.

Optimization of Lipase production from a novel strain Thalassospira permensis M35-15 using Response Surface Methodology.

Lipases can catalyze the hydrolysis of glycerol, esters and long chain fatty acids. A lipase producing isolate M35-15 was screened and identified as Thalassospira permensis using 16S rRNA gene sequence analysis. To our knowledge this is the first report on Thalassospira permensis producing lipases. In this paper the optimization of medium composition for the increase in bacterial lipase was achieved using statistical methods. Firstly the key ingredients were selected by Plackett-Burman experimental design, then the levels of the ingredients were optimized using central composite design of Response Surface Methodology. The predicted optimal lipase activity was 11.49 U under the conditions that medium composition were 5.15 g/l glucose, 11.74 g/l peptone, 6.74 g/l yeast powder and 22.90 g/l olive oil emulsifier.

Thalassospira australica sp. nov. isolated from sea water.

Two Gram-negative, non-pigmented, motile bacteria were isolated from a sea water sample collected at St. Kilda Beach, Port Philip Bay, Victoria, Australia. The two strains were found to grow between 4 and 40 °C, pH 5-10 and tolerate up to 10 % NaCl. A phylogenetic study, based on a 16S rRNA gene sequence analysis indicated that strains NP 3b2(T) and H 94 belong to the genus Thalassospira. The sequence similarity of the 16S rRNA gene between the two new isolates is 99.8 % and between these strains and all validly named Thalassospira species was found to be in the range of 95-99.4 %. The DNA-DNA relatedness between the two strains was found to be 80.2 %, while relatedness with other validly named species of the genus Thalassospira was between 53 and 65 %. The average nucleotide identity (ANI) and the in silico genome-to-genome distance (GGD) between the two bacteria and T. profundimaris WP0211(T), T. xiamenensis M-5(T), 'T. permensis' NBRC 106175(T) and T. lucentensis QMT2(T) was 76-82 % and 21-25 %, respectively. The results of phylogenetic and genomic analysis, together with physiological and biochemical properties, indicated that the two strains represent a new species of the genus Thalassospira. Based on these data, a new species, Thalassospira australica, is proposed with strain NP 3b2(T) (=KMM 6365(T) = JCM 31222(T)) as the type strain.

A marine algicidal Thalassospira and its active substance against the harmful algal bloom species Karenia mikimotoi.

The aim of the present study was to obtain a marine bacterium active against Karenia mikimotoi from the East China Sea and to characterize its extracellular algicidal substances. Using preparative high-performance liquid chromatography (prep-HPLC) and electrospray ionization/quadrupole-time of flight mass spectrometer coupled with a high-performance liquid chromatography (LC/MS-Q-TOF) system, we purified the alga-lysing substance produced by strain ZR-2 and determined its molecular structure. Based on morphology and l6S ribosomal DNA (rDNA) sequence analysis, the ZR-2 strain was highly homologous to Thalassospira species. Algicidal activity against K. mikimotoi was detected in the cell-free filtrate but not in bacterial cells. The alga-lysing substance produced by ZR-2 was ethanol-soluble and thermostable, with a retention time of 6.3 min and a measured elemental composition of C7H5O2 ([M-H](-) ion at m/z 121.0295). The alga-lysing substance produced by ZR-2 was determined to be benzoic acid. Compared with the negative control, both purified ZR-2 bacteria-free filtrate and standard benzoic acid promoted K. mikimotoi cell disruption and induced K. mikimotoi cell content leakage. Our study is the first to report benzoic acid activity against K. mikimotoi as well as production of benzoic acid by a Thalassospira species.