Thalassotalea marina sp. nov., isolated from a marine recirculating aquaculture system, reclassification of Thalassomonas eurytherma as Thalassotalea eurytherma comb. nov. and emended description of the genus Thalassotalea

Genome taxonomy of the genus Thalassotalea and proposal of Thalassotalea hakodatensis sp. nov. isolated from sea cucumber larvae

The genus Thalassotalea is ubiquitous in marine environments, and up to 20 species have been described so far. A Gram-staining-negative, aerobic bacterium, designated strain PTE2T was isolated from laboratory-reared larvae of the Japanese sea cucumber Apostichopus japonicus. Phylogenetic analysis based on the 16S rRNA gene nucleotide sequences revealed that PTE2T was closely related to Thalassotalea sediminis N211T (= KCTC 42588T = MCCC 1H00116T) with 97.9% sequence similarity. ANI and in silico DDH values against Thalassotalea species were 68.5-77.0% and 19.7-24.6%, respectively, indicating the novelty of PTE2T. Based on genome-based taxonomic approaches, strain PTE2T (= JCM 34608T = KCTC 82592T) is proposed as a new species, Thalassotalea hakodatensis sp. nov.

Elevated Temperature-Induced Epimicrobiome Shifts in an Invasive Seaweed Gracilaria vermiculophylla

Epibacterial communities on seaweeds are affected by several abiotic factors such as temperature and acidification. Due to global warming, surface seawater temperatures are expected to increase by 0.5-5 °C in the next century. However, how epibacterial communities associated with seaweeds will respond to global warming remains unknown. In this study, we investigated the response of epibacterial communities associated with the invasive Gracilaria vermiculophylla exposed to 3 °C above ambient temperature for 4 months using a benthocosm system in Kiel, Germany, and 16S rRNA gene amplicon sequencing. The results showed that elevated temperature affected the beta-diversity of the epibacterial communities. Some potential seaweed pathogens such as Pseudoalteromonas, Vibrio, Thalassotalea, and Acinetobacter were identified as indicator genera at the elevated temperature level. Thirteen core raw amplicon sequence variants in the elevated temperature group were the same as the populations distributed over a wide geographical range, indicating that these core ASVs may play an important role in the invasive G. vermicullophylla. Overall, this study not only contributes to a better understanding of how epibacterial communities associated with G. vermiculophylla may adapt to ocean warming, but also lays the foundation for further exploration of the interactions between G. vermiculophylla and its epimicrobiota.

Thalassotalea algicola sp. nov., an alginate-utilizing bacterium isolated from a red alga

A facultatively anaerobic bacterium, strain M1531^T, was isolated from a red alga (Porphyra) at coastal water in Weihai, China. Cells of the novel strain were Gram-stain-negative, rod-shaped, motile by means of a single polar flagellum and around 0.6-0.8 × 2.0-3.0 µm in size. Optimum growth occurred at 30 °C, with 2% (w/v) NaCl and at pH 6.5-7.0. On the basis of the result of phylogenetic analysis of the 16S rRNA gene sequence, stain M1531^T had close relative with Thalassotalea euphylliae KCTC 42743^T (96.9%). Genome sequencing revealed a genome size of 4,061,950 bp, a G + C content of 39.1 mol% and four protein-coding genes related to the degradation of alginate. According to the data obtained, strain M1531^T shared ANI value below 95-96%, dDDH value below 23.8% with the closely related type species. Strain M1531^T had Q-8 as the predominant isoprenoid quinone and possessed Summed Features 3 (C_16:1 ω7c/C_16:1 ω6c), C_16:0 and Summed Features 8 (C_18:1 ω7c/C_18:1 ω6c) as the major fatty acids. The polar lipids of strain M1531^T were identified as phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid and four unidentified lipids. According to the results of the phenotypic, chemotaxonomic characterization, phylogenetic properties and genome analysis, strain M1531^T represents a novel specie of the genus Thalassotalea, for which the name Thalassotalea algicola sp. nov. is proposed. The type strain is M1531^T (= MCCC 1H00400^T = KCTC 72865^T).

Genomics Reveals the Metabolic Potential and Functions in the Redistribution of Dissolved Organic Matter in Marine Environments of the Genus Thalassotalea

Members of the bacterial genus Thalassotalea have been isolated recently from various marine environments, including marine invertebrates. A metagenomic study of the Deepwater Horizon oil plume has identified genes involved in aromatic hydrocarbon degradation in the Thalassotalea genome, shedding light on its potential role in the degradation of crude oils. However, the genomic traits of the genus are not well-characterized, despite the ability of the species to degrade complex natural compounds, such as agar, gelatin, chitin, or starch. Here, we obtained a complete genome of a new member of the genus, designated PS06, isolated from marine sediments containing dead marine benthic macroalgae. Unexpectedly, strain PS06 was unable to grow using most carbohydrates as sole carbon sources, which is consistent with the finding of few ABC transporters in the PS06 genome. A comparative analysis of 12 Thalassotalea genomes provided insights into their metabolic potential (e.g., microaerobic respiration and carbohydrate utilization) and evolutionary stability [including a low abundance of clustered regularly interspaced short palindromic repeats (CRISPR) loci and prophages]. The diversity and frequency of genes encoding extracellular enzymes for carbohydrate metabolism in the 12 genomes suggest that members of Thalassotalea contribute to nutrient cycling by the redistribution of dissolved organic matter in marine environments. Our study improves our understanding of the ecological and genomic properties of the genus Thalassotalea.

Thalassotalea mangrovi sp. nov., a bacterium isolated from marine mangrove sediment

A novel Gram-stain-negative, strictly aerobic bacterium that has a rod-like shape with a single polar flagellum in the exponential phase of growth and a spherical or ovoid shape without a flagellum in the stationary phase was isolated from a mangrove wetland sediment sample collected at Beilun Estuary National Nature Reserve, Guangxi Province, PR China and designated strain ZS-4^T. This strain grew optimally at pH 6.0-8.0, at a temperature of 37 °C and in the presence of 3-4 % (w/v) NaCl. Its polar lipid profile included phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid and two uncharacterized lipids. Ubiquinone 8 (Q-8) was the sole respiratory quinone and the cellular fatty acids were dominated by C_17 : 1ω8c and C_16 : 0. A phylogenetic analysis based on the 16S rRNA gene sequence showed that strain ZS-4^T exhibited its highest similarities to the type strains Thalassotalea litorea HMF4135^T (97.8 %) and Thalassotalea ponticola GJSW-36^T (95.9 %). A whole genome-level comparison of strain ZS-4^T with T. litorea MCCC 1K03283^T revealed an average nucleotide identity value of 75.6 % and a calculated DNA-DNA hybridization value of 19.6 %. In addition, the genomic DNA G+C content of strain ZS-4^T was 45.9 mol%. Thus, based on analyses of its morphology, physiology, fatty acid composition and 16S rRNA gene sequence, strain ZS-4^T should be considered a novel species of the genus Thalassotalea, with the proposed name Thalassotaleamangrovi sp. nov. The type strain is ZS-4^T (=KCTC 72399^T=MCCC 1K03630^T).

Effects of water recirculation rate on the microbial community and water quality in relation to the growth and survival of white shrimp (Litopenaeus vannamei)

Background

Microbial community and its management are crucial to the stabilization of culture environment for recirculating aquaculture system (RAS). Although several studies have been carried out for the microbial community of RAS, few studies were on the RAS for shrimp. Water recirculation ratio is an important factor for the microbial community and the management of RAS. Therefore, low (LC), medium (MC) and high (HC) recirculation ratio systems were set to explore the microbial community constitution of RAS for Litopenaeus vannamei and study the effect of water recirculation rate on it.

Results

The bacterial community of bioreactor was mainly dominated by Proteobacteria (41.6–70.7%), followed with Planctomycetes (12.5–31.0%), Bacteroidetes (10.5–26.0%), Actinobacteria (1.1–4.8%) and Verrucomicrobia (1.4–6.8%) phylum. The most dominant family of bioreactor was Rhodobacteraceae or Planctomycetaceae. The bacterial community of culture water was simpler than bioreactor and dominated by Proteobacteria (61.8–96.4%). The dominant bacterial groups of bioreactor and culture water are also different among the three water recirculation rates, and the proportions of dominant groups showed a trend with the variety of water recirculation rate. Water quality indexes including ammonia and nitrite decreased with the increasing of water recirculation rate. According to the growth performance of L. vannamei, shrimp had better performance of growth rate and final weight in MC and HC, however, shrimp had higher survival and yield in LC. Shrimp survival and yield had an inverse correlation with water recirculation rate.

Conclusions

The results demonstrate the microbial community of RAS for shrimp, highlight the importance of further studies on the function of bacterial taxa, and promote the understanding of the effects of water recirculation rate on the microbiota. The findings suggest that water recirculation rate has important impacts on the microbial community, water quality and shrimp growth. Increasing the water recirculation rate could improve the water quality and promote the growth of shrimp. However, the survival rate and yield of L. vannamei are higher under low water recirculation rate. Recirculation rate is an effective method to manage RAS, and its impact on RAS needs further study, especially in the application of low level of water recirculation.

Thalassotalea insulae sp. nov., isolated from tidal flat sediment

A Gram-stain-negative, aerobic, motile and rod-shaped or ovoid bacterial strain, designated JDTF-40^T, was isolated from a tidal flat in Jindo, an island of the Republic of South Korea. Strain JDTF-40^T grew optimally at pH 7.0-8.0, at 30 °C and in the presence of 2 % (w/v) NaCl. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences showed that strain JDTF-40^T fell within the cluster comprising the type strains of Thalassotalea species. Strain JDTF-40^T exhibited 16S rRNA gene sequence similarity values of 93.8-95.7 % to the type strains of Thalassotalea species. Strain JDTF-40^T 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 of strain JDTF-40^T were phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid, one unidentified glycolipid and three unidentified lipids. The DNA G+C content of strain JDTF-40^T was 41.3 mol%. Differential phenotypic properties, together with the phylogenetic distinctiveness, demonstrated that strain JDTF-40^T is distinct from recognized species of the genus Thalassotalea. On the basis of the data presented here, strain JDTF-40^T is considered to represent a novel species of the genus Thalassotalea, for which the name Thalassotalea insulae sp. nov. is proposed. The type strain is JDTF-40^T (=KACC 19433^T=KCTC 62186^T=NBRC 113040^T).

Thalassotalea atypica sp. nov., isolated from seawater, and emended description of Thalassotalea eurytherma

A novel Gram-stain-negative, straight or slightly curved rod-shaped, non-spore-forming, non-flagellated, strictly aerobic strain, designated RZG4-3-1^T, was isolated from coastal seawater of Rizhao, China (119.625° E 35.517° N). The organism grew optimally at 24-28 °C, at pH 7.0 and in the presence of 2.0 % (w/v) NaCl. The strain required seawater or artificial seawater for growth, and NaCl alone did not support growth. Strain RZG4-3-1^T contained ubiquinone 8 (Q-8) as the major respiratory quinone and contained C16 : 1ω7c and/or C16 : 1ω6c and C16 : 0 as the dominant fatty acids. The polar lipids of strain RZG4-3-1^T were phosphatidylethanolamine, phosphatidylglycerol and one unidentified aminophospholipid. The DNA G+C content of strain RZG4-3-1^T was 40.1 mol%. Strain RZG4-3-1^T exhibited the highest 16S rRNA gene sequence similarity value (96.0 %) to Thalassotalea eurytherma JCM 18482^T. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain RZG4-3-1^T belonged to the genus Thalassotalea. On the basis of polyphasic analyses, strain RZG4-3-1^T represents a novel species of the genus Thalassotalea, for which the name Thalassotalea atypica sp. nov. is proposed. The type strain is RZG4-3-1^T (=JCM 31894^T=KCTC 52745^T=MCCC 1K03276^T). An emended description of Thalassotalea eurytherma is also provided.

Thalassotalea coralli sp. nov., isolated from the torch coral Euphyllia glabrescens

Strain Eup a-8^T, isolated from a torch coral Euphyllia glabrescens, was characterized using a polyphasic taxonomy approach. Cells of strain Eup a-8^T were Gram-staining-negative, aerobic, motile by means of a single polar flagellum, poly-β-hydroxybutyrate-containing, rod-shaped and formed white colonies. Optimal growth occurred at 25-30 °C, pH 7-8, and in the presence of 2 % NaCl. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Eup a-8^T belonged to the genus Thalassotalea and showed the highest levels of sequence similarity with respect to Thalassotalea ganghwensis JC2041^T (97.1 %). Strain Eup a-8^T contained C17 : 1ω8c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C14 : 0 and iso-C16 : 0 as the predominant fatty acids. The only isoprenoid quinone was Q-8. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and one uncharacterized phospholipid. Genomic DNA G+C content of strain Eup a-8^T was 41.5 mol%. The DNA-DNA hybridization value for strain Eup a-8^T with Thalassotalea ganghwensis JC2041^T was less than 70 %. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain Eup a-8^T should be classified as a novel species of the genus Thalassotalea, for which the name Thalassotalea coralli sp. nov. is proposed. The type strain is Eup a-8^T (=BCRC 80967^T=LMG 29478^T=KCTC 52169^T).

Thalassotaleaprofundi sp. nov. isolated from a deep-sea seamount

The Gram-stain-negative, rod-shaped, strictly aerobic, motile bacterial strain, designated YM155^T, was isolated from a seamount near the Yap Trench in the tropical western Pacific. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain YM155^T was related to the genus Thalassotalea and had highest 16S rRNA gene sequence similarities with the type strains of Thalassotalea piscium T202^T (97.2 %) and Thalassotalea agariperforans M-M1^T (97.2 %). The predominant cellular fatty acids were C17 : 1ω8c, summed feature 3 (composed of iso-C15 : 0 2-OH and/or C16 : 1ω7c) and iso-C16 : 0. Ubiquinone 8 (Q-8) was the respiratory quinone. The polar lipid profile contained phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and one unidentified lipid. The genomic DNA G+C content of strain YM155^T was 36.1 mol%. On the basis of the evidence presented in this study, strain YM155^T represents a novel species of the genus Thalassotalea, for which we propose the name Thalassotalea profundi sp. nov. (type strain YM155^T=KACC 18563^T=CGMCC 1.15922^T).

Thalassotalea litorea sp. nov., isolated from seashore sand

A novel Gram-stain-negative, aerobic and rod-shaped marine bacterium, designated strain HMF4135T, was isolated from a sand sample which was collected from the seashore of the South Sea, Republic of Korea. It required NaCl for growth and exhibited optimal growth at 30 °C, with 2 % (w/v) NaCl and at pH 7-8. Cellular fatty acids were dominated by C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 1ω9c and C12 : 0 3-OH. The predominant isoprenoid quinone was ubiquinone-8 (Q-8). Polar lipids consisted of phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content was 41.9 mol%. Phylogeny based on 16S rRNA gene sequences showed that strain HMF4135T formed a distinct species-level lineage within the genus Thalassotalea of the class Gammaproteobacteria and was most closely related to Thalassotalea ponticola GJSW-36T (96.4 % similarity). Based on the distinctive phenotypic characteristics and phylogenetic analysis, it is concluded that strain HMF4135T represents a novel species of the genus Thalassotalea, for which the name Thalassotalea litorea sp. nov. is proposed. The type strain is HMF4135T (=KCTC 52154T=NBRC 112672T).

Thalassotalea crassostreae sp. nov., isolated from Pacific oyster

A Gram-staining-negative, aerobic, rod-shaped bacterial strain, designated LPB0090T, was isolated from the Pacific oyster, Crassostreagigas, collected from the Yeongheung Island, Korea (37° 15' 16.1″ N; 126° 29' 46.5″ E). The complete genome sequence of LPB0090T (accession number CP017689) was 3 861 670 bp long with a DNA G+C content of 38.8 mol%. The genome included 3245 protein-coding genes and six copies of rRNA operons. On the basis of the results of 16S rRNA gene sequence analysis, LPB0090T was found to form an independent phyletic line within the genus Thalassotalea, with 94.7-96.0 % sequence similarities to the previously known species of the genus. The isoprenoid quinone (Q-8) and major fatty acids (C16 : 0, C17 : 1 ω8c, and C16 : 1 ω7c and/or C16 : 1 ω6c) of the isolate were similar to those of the other members of the genus Thalassotalea. A number of phenotypic features, however, distinguished LPB0090T from its closest neighbour Thalassotalea ponticola as well as other species of the genus Thalassotalea. On the basis of the phylogenetic, genomic and phenotypic data presented in this study, the strain was classified as representing a novel species of the genus Thalassotalea. Therefore, the name Thalassotalea crassostreae sp. nov. is proposed for the isolate. The type strain is LPB0090T (=KACC 18695T=JCM 31189T).

Thalassotalea euphylliae sp. nov., isolated from the torch coral Euphyllia glabrescens

Strain Eup-16T, isolated from the torch coral Euphyllia glabrescens, was characterized using a polyphasic taxonomy approach. Cells of strain Eup-16T were Gram-staining-negative, aerobic, motile by means of a single polar flagellum, contained poly-β-hydroxybutyrate, rod-shaped and formed pale yellow colonies. Optimal growth occurred at 25-30 °C, pH 7.5-9 and in the presence of 1 % NaCl. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Eup-16T belonged to the genus Thalassotalea and was most closely related to Thalassotalea montiporae CL-22T with sequence similarity of 98.4 %. Strain Eup-16T contained summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C18 : 1ω7c, C16 : 0 and C17 : 1ω8c as the predominant fatty acids. The predominant isoprenoid quinone was Q-8. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The genomic DNA G+C content of strain Eup-16T was 43.2 mol%. The DNA-DNA hybridization value for strain Eup-16T with T. montiporae CL-22T was less than 34 %. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain Eup-16T should be classified as a representative of a novel species of the genus Thalassotalea, for which the name Thalassotalea euphylliae sp. nov. is presented. The type strain is Eup-16T (=BCRC 80910T=LMG 29001T=KCTC 42743T).

Thalassotalea montiporae sp. nov., isolated from the encrusting pore coral Montipora aequituberculata

A bacterial strain, designated CL-22T, was isolated from an encrusting pore coral, Montipora aequituberculata, collected off the coast of Southern Taiwan. Its taxonomic position was investigated using a polyphasic approach. Cells of strain CL-22T were Gram-stain-negative, aerobic, motile by means of a single polar flagellum, rod-shaped and formed yellow colonies. Optimal growth occurred at 30 °C, pH 6.5-7 and in 2 % (w/v) NaCl. A neighbour-joining phylogenetic tree, based on 16S rRNA gene sequences, showed that strain CL-22T fell into the clade comprising the type strains of species of the genus Thalassotalea. Strain CL-22T exhibited 16S rRNA gene sequence similarity values of 94.7-97.1 % to the type strains of species of the genus Thalassotalea. The major fatty acids (>10 %) of strain CL-22T were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The predominant isoprenoid quinone was Q-8. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The genomic DNA G+C content of strain CL-22T was 41.2 mol%. The differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain CL-22T should be classified as a novel species of the genus Thalassotalea; the name Thalassotalea montiporae sp. nov. is proposed. The type strain is CL-22T (=LMG 24827T=BCRC 17940T).

N-Acyl Dehydrotyrosines, Tyrosinase Inhibitors from the Marine Bacterium Thalassotalea sp. PP2-459

Thalassotalic acids A-C and thalassotalamides A and B are new N-acyl dehydrotyrosine derivatives produced by Thalassotalea sp. PP2-459, a Gram-negative bacterium isolated from a marine bivalve aquaculture facility. The structures were elucidated via a combination of spectroscopic analyses emphasizing two-dimensional NMR and high-resolution mass spectrometric data. Thalassotalic acid A (1) displays in vitro inhibition of the enzyme tyrosinase with an IC50 value (130 μM) that compares favorably to the commercially used control compounds kojic acid (46 μM) and arbutin (100 μM). These are the first natural products reported from a bacterium belonging to the genus Thalassotalea.