Hwangdonia lutea sp. nov., isolated from the Haima cold seep, South China Sea.

A Gram-stain-negative, orange-yellow, rod-shaped bacterium, designated strain SCSIO 19198T, was isolated from sediment of the Haima cold seep in the South China Sea, PR China. The strain was aerobic and non-motile. Growth of strain SCSIO 19198T occurred at pH 7-9 (optimum, pH 7), 15-37 °C (optimum, 25-32 °C) and with 3-8 % (w/v) NaCl (optimum, 3-6 % NaCl). Phylogenetic analyses based on 16S rRNA sequences revealed that strain SCSIO 19198T belonged to the genus Hwangdonia, having the highest similarity to Hwangdonia seohaensis HD-3T (98.35 %), followed by Algibacter aquimarinus KYW589T (95.17 %) and Gelatiniphilus marinus GYP-24T (94.89 %). The DNA G+C content was 35.92 mol%. The average nucleotide identity value between the genome of strain SCSIO 19198T and that of H. seohaensis HD-3T was 88.49 %. The digital DNA-DNA hybridization value between strain SCSIO 19198T and H. seohaensis HD-3T was 36 %. The major fatty acids (>10 %) of strain SCSIO 19198T were iso-C15 : 0, iso-C15 : 1 G, summed feature 3 (C16 : 1 ω6c/C16 : 1 ω7c) and anteiso-C15 : 0. MK-6 was the only detected respiratory quinone. The polar lipids of strain SCSIO 19198T included phosphatidylethanolamine, two aminolipids, glycolipid and two unidentified lipids. The phenotypic, phylogenetic, chemotaxonomic and genomic data clearly suggest that strain SCSIO 19198T represents a novel species of the genus Hwangdonia, for which the name Hwangdonia lutea sp. nov. is proposed. The type strain is SCSIO 19198T (=MCCC 1K08674T=KCTC 102078T).

Bacterial carbonic anhydrase-induced carbonates mitigate soil erosion in biological soil crusts.

Soil erosion is a significant environmental issue worldwide, particularly in island regions where land resources are exceedingly scarce. Biological soil crusts play a crucial role in mitigating soil erosion, yet the precise effect and mechanism of biological soil crusts against erosion remain ambiguous. In this study, biological soil crusts at various developmental stages from a tropical coral island in the South China Sea were chosen to investigate the role of carbonic anhydrase in mitigating erosion. A cohesive strength meter, real-time quantitative PCR, and 16S rRNA gene high-throughput sequencing were employed to assess variations in soil antiscouribility as well as bacterial abundance and composition during the formation and development of biological soil crusts. Scanning electron microscopy was utilized to detect carbonates induced by bacterial carbonic anhydrase and elucidate their role in the solidification of sand particles. The findings indicate that the formation and development of biological soil crusts significantly enhance anti-scouribility. Comparison to those of bare coral sand, the shear stress increased from 0.35 to 1.11 N/m2 in the dark biocrusts. Moreover, significantly elevated carbonic anhydrase activity was observed in biological soil crusts, demonstrating a positive correlation with antiscouribility. In addition, there was a significant increase in bacterial abundance within the biological soil crusts. The enrichment of Cyanobacteriales and Chloroflexales potentially contributed to the increased carbonic anhydrase activity and antiscouribility. Furthermore, three cyanobacterial strains with carbonic anhydrase activity were isolated from biological soil crusts and subsequently confirmed to enhance sand solidification through microbial carbonate precipitation. This study presents initial evidence for the role of microbial carbonic anhydrase in enhancing the antiscouribility of biological soil crusts during their formation and development. These findings offer novel insights into the functional and mechanistic dimensions underlying the mitigation of soil erosion facilitated by biological soil crusts, which are valuable for implementing sustainable biorestoration and environmental management technologies to prevent soil erosion.

m6A-regulated tumor glycolysis: new advances in epigenetics and metabolism.

Glycolytic reprogramming is one of the most important features of cancer and plays an integral role in the progression of cancer. In cancer cells, changes in glucose metabolism meet the needs of self-proliferation, angiogenesis and lymphangiogenesis, metastasis, and also affect the immune escape, prognosis evaluation and therapeutic effect of cancer. The n6-methyladenosine (m6A) modification of RNA is widespread in eukaryotic cells. Dynamic and reversible m6A modifications are widely involved in the regulation of cancer stem cell renewal and differentiation, tumor therapy resistance, tumor microenvironment, tumor immune escape, and tumor metabolism. Lately, more and more evidences show that m6A modification can affect the glycolysis process of tumors in a variety of ways to regulate the biological behavior of tumors. In this review, we discussed the role of glycolysis in tumor genesis and development, and elaborated in detail the profound impact of m6A modification on different tumor by regulating glycolysis. We believe that m6A modified glycolysis has great significance and potential for tumor treatment.

Advances in Synthetic-Biology-Based Whole-Cell Biosensors: Principles, Genetic Modules, and Applications in Food Safety.

A whole-cell biosensor based on synthetic biology provides a promising new method for the on-site detection of food contaminants. The basic components of whole-cell biosensors include the sensing elements, such as transcription factors and riboswitches, and reporting elements, such as fluorescence, gas, etc. The sensing and reporting elements are coupled through gene expression regulation to form a simple gene circuit for the detection of target substances. Additionally, a more complex gene circuit can involve other functional elements or modules such as signal amplification, multiple detection, and delay reporting. With the help of synthetic biology, whole-cell biosensors are becoming more versatile and integrated, that is, integrating pre-detection sample processing, detection processes, and post-detection signal calculation and storage processes into cells. Due to the relative stability of the intracellular environment, whole-cell biosensors are highly resistant to interference without the need of complex sample preprocessing. Due to the reproduction of chassis cells, whole-cell biosensors replicate all elements automatically without the need for purification processing. Therefore, whole-cell biosensors are easy to operate and simple to produce. Based on the above advantages, whole-cell biosensors are more suitable for on-site detection than other rapid detection methods. Whole-cell biosensors have been applied in various forms such as test strips and kits, with the latest reported forms being wearable devices such as masks, hand rings, and clothing. This paper examines the composition, construction methods, and types of the fundamental components of synthetic biological whole-cell biosensors. We also introduce the prospect and development trend of whole-cell biosensors in commercial applications.

Applications of the Whole-Cell System in the Efficient Biosynthesis of Heme.

Heme has a variety of functions, from electronic reactions to binding gases, which makes it useful in medical treatments, dietary supplements, and food processing. In recent years, whole-cell system-based heme biosynthesis methods have been continuously explored and optimized as an alternative to the low-yield, lasting, and adverse ecological environment of chemical synthesis methods. This method relies on two biosynthetic pathways of microbial precursor 5-aminolevulinic acid (C4, C5) and three known downstream biosynthetic pathways of heme. This paper reviews the genetic and metabolic engineering strategies for heme production in recent years by optimizing culture conditions and techniques from different microorganisms. Specifically, we summarized and analyzed the possibility of using biosensors to explore new strategies for the biosynthesis of heme from the perspective of synthetic biology, providing a new direction for future exploration.

Description of Prasinibacter corallicola gen. nov., sp. nov., a zeaxanthin-producing bacterium isolated from stony coral Porites lutea.

Thermal stress is considered one of the main causes of mass scleractinian coral degradation; however, it is still unknown how corals can adapt to future global warming. In this study, 11 strains of coral-associated Flavobacteria were shown to produce zeaxanthin, a carotenoid antioxidant, which may help coral holobionts to alleviate thermal stress. In addition, a novel zeaxanthin-producing Flavobacterium, designated R38T, was identified using polyphasic taxonomy. Although strain R38T shared a maximum 16S rRNA gene sequence similarity of 93% with Mesoflavibacter aestuarii KYW614T, phylogenetic analyses based on whole genome and 16S rRNA gene sequences revealed that strain R38T forms a distinct branch in a robust cluster composed of strain R38T and Leptobacterium flavescens KCTC 22160T under the family Flavobacteriaceae. Strain R38T exhibited average nucleotide identities of 70.2% and 72.5% for M. aestuarii KYW614T and L. flavescens KCTC 22160T, respectively. The only detected respiratory quinone was menaquinone 6 (MK-6). The genomic DNA G + C content was 33.2 mol%. The major polar lipids were phosphatidylmethylethanolamine, phosphatidylethanolamine, one unidentified ninhydrin phospholipid, three unidentified ninhydrin-positive lipids, and three unidentified lipids. The major cellular fatty acids were iso - C15: 0, iso - C15: 0 ω6c, C16:2 DMA, and C13:1 ω3c. The distinct biochemical, chemotaxonomic, phylogenetic, and phylogenomic differences from validly published taxa suggest that strain R38T represents a new species of a new genus, for which Prasinibacter corallicola gen. nov., sp. nov. is proposed. The type strain R38T (= MCCC 1K03889T = KCTC 72444T).

Use of a purified ß-glucosidase from coral-associated microorganisms to enhance wine aroma.

BACKGROUND: ß-Glucosidases (3.2.1.21) play essential roles in the removal of nonreducing terminal glucosyl residues from saccharides and glycosides. However, the full potential and different applications of recombinant high-yield microbial ß-glucosidase-producing systems remain to be tackled. RESULTS: A ß-glucosidase gene designated as Mg132 was isolated from a coral microorganism by high-throughput sequencing and functional screening. The deduced amino acid sequences of Mg132 showed a highest identity of 97% with ß-glucosidase predicted in the GenBank database. This gene was cloned and overexpressed in Escherichia coli BL21 (DE3) for the first time. The optimal pH and temperature of purified recombinant Mg132 were 8.0 and 50 °C respectively. It exhibited a high level of stability at high concentration of glucose and ethanol, and glucose concentrations below 300 mmol L-1 distinctly stimulated p-nitrophenyl-ß-d-glucopyranoside hydrolysis, reaching 200% at 15% ethanol. The Km and Vmax values were 0.293 mmol L-1 and 320 µmol min-1  mg-1 respectively while using p-nitrophenyl-ß-d-glucopyranoside as a substrate. Wine treated with Mg132 had an obvious positive catalytic specificity for glycosides, which give a pleasant flavor of temperate fruity and floral aromas. The total concentration of fermentative volatiles was 201.42 ± 10.22 µg L-1 following Mg132 treatment and 99.21 ± 7.72 µg L-1 in control samples. CONCLUSION: Good tolerance of winemaking and aroma fermentative properties suggest that Mg132 has potential application in aroma enhancement in wine and warrants further study. © 2021 Society of Chemical Industry.

Gestational bisphenol A exposure induces fatty liver development in male offspring mice through the inhibition of HNF1b and upregulation of PPARγ.

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) associated with non-alcoholic fatty liver disease (NAFLD). The effects of gestational BPA exposure on hepatic lipid accumulation in offspring are not fully understood. Here, we investigate the sex-dependent effects of gestational BPA exposure on hepatic lipid and glucose metabolism in the offspring of mice to reveal the mechanisms underlying gestational BPA exposure-associated NAFLD. Pregnant mice were administered gavage with or without 1 µg kg-1 day-1 BPA at embryonic day 7.5 (E7.5)-E16.5. Hepatic glucose and lipid metabolism were evaluated in these models. Both male and female offspring mice exhibited hepatic fatty liver after BPA treatment. Lipid accumulation and dysfunction of glucose metabolism were observed in male offspring. We revealed abnormal expression of lipid regulators in the liver and that inhibition of peroxisome proliferator-activated receptor γ (PPARγ) repressed hepatic lipid accumulation induced by gestational BPA exposure. We also found a sex-dependent decrease of hepatocyte nuclear factor 1b (HNF1b) expression in male offspring. The transcriptional repression of PPARγ by HNF1b was confirmed in L02 cells. Downregulation of HNF1b, upregulation of PPARγ, and subsequent upregulation of hepatic lipid accumulation were essential for NAFLD development in male offspring gestationally exposed to BPA as well as BPA-exposed adult male mice. Dysregulation of the HNF1b/PPARγ pathway may be involved in gestational BPA exposure-induced NAFLD in male offspring. These data provide new insights into the mechanism of gestational BPA exposure-associated sex-dependent glucose and lipid metabolic dysfunction. Graphical abstract Schematic of the mechanism of gestational BPA exposure-induced glucose and lipid metabolic dysfunction.

The Main Alkaloids in Uncaria rhynchophylla and Their Anti-Alzheimer's Disease Mechanism Determined by a Network Pharmacology Approach.

Alzheimer's disease (AD) is a growing concern in modern society, and effective drugs for its treatment are lacking. Uncaria rhynchophylla (UR) and its main alkaloids have been studied to treat neurodegenerative diseases such as AD. This study aimed to uncover the key components and mechanism of the anti-AD effect of UR alkaloids through a network pharmacology approach. The analysis identified 10 alkaloids from UR based on HPLC that corresponded to 90 anti-AD targets. A potential alkaloid target-AD target network indicated that corynoxine, corynantheine, isorhynchophylline, dihydrocorynatheine, and isocorynoxeine are likely to become key components for AD treatment. KEGG pathway enrichment analysis revealed the Alzheimers disease (hsa05010) was the pathway most significantly enriched in alkaloids against AD. Further analysis revealed that 28 out of 90 targets were significantly correlated with Aß and tau pathology. These targets were validated using a Gene Expression Omnibus (GEO) dataset. Molecular docking studies were carried out to verify the binding of corynoxine and corynantheine to core targets related to Aß and tau pathology. In addition, the cholinergic synapse (hsa04725) and dopaminergic synapse (hsa04728) pathways were significantly enriched. Our findings indicate that UR alkaloids directly exert an AD treatment effect by acting on multiple pathological processes in AD.

High Diversity of ß-Glucosidase-Producing Bacteria and Their Genes Associated with Scleractinian Corals.

ß-Glucosidase is a microbial cellulose multienzyme that plays an important role in the regulation of the entire cellulose hydrolysis process, which is the rate-limiting step in bacterial carbon cycling in marine environments. Despite its importance in coral reefs, the diversity of ß-glucosidase-producing bacteria, their genes, and enzymatic characteristics are poorly understood. In this study, 87 ß-glucosidase-producing cultivable bacteria were screened from 6 genera of corals. The isolates were assigned to 21 genera, distributed among three groups: Proteobacteria, Firmicutes, and Actinobacteria. In addition, metagenomics was used to explore the genetic diversity of bacterial ß-glucosidase enzymes associated with scleractinian corals, which revealed that these enzymes mainly belong to the glycosidase hydrolase family 3 (GH3). Finally, a novel recombinant ß-glucosidase, referred to as Mg9373, encompassing 670 amino acids and a molecular mass of 75.2 kDa, was classified as a member of the GH3 family and successfully expressed and characterized. Mg9373 exhibited excellent tolerance to ethanol, NaCl, and glucose. Collectively, these results suggest that the diversity of ß-glucosidase-producing bacteria and genes associated with scleractinian corals is high and novel, indicating great potential for applications in the food industry and agriculture.

Aliikangiella coralliicola sp. nov., a bacterium isolated from coral Porites lutea, and proposal of Pleioneaceae fam. nov. to accommodate Pleionea and Aliikangiella.

A novel Gram-stain-negative, non-endospore-forming, motile, and aerobic bacterial strain, M105T, was isolated from coral Porites lutea, and was subjected to a polyphasic taxonomic study. Global alignment based on 16S rRNA gene sequences indicated that M105T shares the highest sequence identity of 94.5 % with Aliikangiella marina GYP-15T. The average nucleotide identity (ANI) and average amino acid identity (AAI) between M105T and A. marina GYP-15T was 69.8 and 71.6 %, respectively. On the basis of the results of phenotypic, chemotaxonomic, phylogenetic, phylogenomic, and comparative genomic analyses, it is concluded that M105T should represent a novel species in the genus Aliikangiella, for which the name Aliikangiella coralliicola sp. nov. is proposed. The type strain is M105T (=MCCC 1K03773T= KCTC 72442T). Furthermore, the family Kangiellaceae was classified into two families on the basis of phylogenetic, phylogenomic, polar lipid profile and motility variations. The novel family Pleioneaceae fam. nov. is proposed to accommodate the genera Aliikangiella and Pleionea.

Denitrobaculum tricleocarpae gen. nov., sp. nov., a marine bacterium from coralline algae Tricleocarpa sp.

A Gram-stain-negative, non-spore-forming, aerobic, motile, curved rod-shaped bacterium, designed strain R148T was isolated from a coralline algae Tricleocarpa sp. collected from Weizhou island, PR China. The optimal growth of R148T occurred at 25 °C, pH 8-9 in the presence of 0.5 % (w/v) NaCl on the basis of amended marine broth 2216. The genomic DNA G+C content was 59.5 mol%. The only detected respiratory quinone was Q-10. The major polar lipids were phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and three unidentified ninhydrin-positive lipids. The major cellular fatty acids were C18 : 1ω7c, C16 : 1ω7c, C19 : 0cyclo 9, 10 DMA and C18 : 0. The results of 16S rRNA gene-based global alignment indicated that the closest neighbour of strain R148T was Pelagibius litoralis DSM 21314T (93.1 % similarity), the second is Limibacillus halophilus KCTC 42420T (92.2 %). The results of phylogenetic analysis indicated that R148T forms a distinct branch in the robust clade of R148T and P. litoralis DSM 21314T, while the taxonomic position of this clade in the family Rhodospirillaceae is ambiguous among phylogenetic approaches. The low 16S rRNA gene similarity and distinct polar lipid and cellular fatty acid profile could readily distinguish R148T from closely related type strains. So R148T is suggested to represent a novel species in a novel genus, for which the name Denitrobaculum tricleocarpae gen. nov., sp. nov. is proposed. The type strain is R148T (=MCCC 1K03781T=KCTC 72137T).

Exilibacterium tricleocarpae gen. nov., sp. nov., a marine bacterium from coralline algae Tricleocarpa sp.

A Gram-stain-negative, non-spore-forming, aerobic, curved rod-shaped bacterium, designed strain R142T, was isolated from a coralline algae Tricleocarpa sp. in the Beibu Gulf, China. Optimal growth occurred with 0-0.5 % (w/v) NaCl, at 25 °C and at pH 8. Global alignment based on 16S rRNA gene sequences indicated that strain R142T shared 93.8 % similarity with its closest type strain, Pseudomaricurvus alkylphenolicus KU14GT. Phylogenetic analyses showed that strain R142T forms a distinct branch alongside Maricurvus nonylphenolicus KU41ET, Pseudoteredinibacter isoporae SW-11T, Pseudomaricurvus alkylphenolicus KU14GT, Pseudomaricurvus alcaniphilus MEBiC06469T and Aestuariicella hydrocarbonica SM-6T. The major polar lipids of strain R142T were phosphatidylethanolamine and phosphatidylglycerol. The primary cellular fatty acids were C16 : 0, C16 : 1ω7c, C18 : 1ω7c, C18 : 0 and C14 : 0. The genome DNA G+C ratio was 56.4 mol%. The only detected respiratory quinone was ubiquinone 8. The low 16S rRNA gene sequence similarity and differences in cellular fatty acids readily distinguished strain R142T from all validly published type strains. Strain R142T is therefore suggested to represent a novel species of a new genus, for which the name Exilibacterium tricleocarpae gen. nov., sp. nov. is proposed. The type strain of Exilibacterium tricleocarpae is R142T (=MCCC 1K03816T=KCTC 72138T).

Poritiphilus flavus gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from coral Porites lutea.

A novel Gram-stain-negative, non-endospore-forming, non-motile, aerobic bacterium (strain R33T) was isolated from coral Porites lutea and subjected to a polyphasic taxonomic study. The G+C content was 44.5 mol%. The only detected respiratory quinone was menaquinone 6 (MK-6). The major cellular fatty acids were iso-C15 : 0 and iso-C15 : 1 ω6c. The major polar lipids were phosphatidylethanolamine and two unidentified lipids. Global alignment based on 16S rRNA gene sequences indicated that strain R33T shares the highest sequence identity of 93.2 % with Muriicola marianensis A6B8T in the family Flavobacteriaceae. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R33T forms a distinct branch in a stable clade comprising strain R33T and members of the genera Muriicola, Robiginitalea, Eudoraea and Zeaxanthinibacter. The phylogenomic analysis also supported this 16S rRNA gene-based phylogenetic result. Comparative genomic analysis indicated that strain R33T is rich in AraC-type DNA-binding domain-containing protein-coding genes, which means the regulation of carbon utilization is very complex. Low 16S rRNA gene identity, different polar lipids and/or cellular fatty acid profiles could readily distinguish strain R33T from any validly published type strains. Therefore, strain R33T is suggested to represent a new species in a new genus, for which the name Poritiphilus flavus gen. nov., sp. nov. is proposed. The type strain is R33T (=MCCC 1K03853T=KCTC 72443T).

Characterization of ssDNA aptamers specifically directed against Trachinotus ovatus NNV (GTONNV)-infected cells with antiviral activities.

Nervous necrosis virus (NNV), is one of the most fatal viruses in marine fish aquaculture, and is capable of infecting over 50 different fish species. Trachinotus ovatus NNV (GTONNV) was isolated from diseased golden pompano. This T. ovatus strain was isolated from Guangxi, China. Single-stranded DNA (ssDNA) aptamers with high specificity for GTONNV-infected T. ovatus cerebellum cells (TOCC) were produced by Systematic Evolution of Ligands by Exponential Enrichment (SELEX). The characterization of these aptamers was performed using flow cytometry and laser scanning confocal microscopy. The selected aptamers showed significant specificity for GTONNV-infected cells. Based on MFOLD prediction, aptamers formed distinct stem-loop structures that could form the basis for the aptamers' specific binding to their cellular targets. Protease treatment results revealed that the target molecules for aptamers TNA1, TNA4 and TNA19 within GTONNV-infected cells may be membrane proteins that were trypsin-sensitive. Specific endocytosis of aptamer TNA1, TNA4 and TNA19 into GTONNV-infected cells was also shown. The selected aptamers demonstrated antiviral effects against GTONNV both in vitro and in vivo. This is the first time that aptamers targeting GTONNV-infected T. ovatus cells have been selected and characterized. These aptamers hold promise as rapid diagnostic reagents or targeted therapeutic drugs against GTONNV.

Proposal of Parashewanella gen. nov. to accommodate Parashewanella curva sp. nov. and Parashewanella spongiae comb. nov. in the Shewanellaceae.

A Gram-stain-negative, non-spore-forming, motile, aerobic, curved rod shaped bacterium, designed strain C51T, was isolated from coral (genus Porites) sampled at Weizhou Island, China. The optimal growth occurred in 2-3 % NaCl (w/v), at 25 °C and pH 8. Phylogenetic analyses based on the 16S rRNA gene, the gyrB gene and the Up-to-date Bacterial Core Gene set (92 genes) indicated that strain C51T forms a stable cluster with Shewanella spongiae KCTC 22492T, and had 94 % 16S rRNA gene similarity to its closest type strain S. spongiae KCTC 22492T. The only detected respiratory quinone was Q-8 and it could not produce menaquinone. The genome DNA G+C content was 40.1 mol%. The major cellular fatty acids were iso-C11:0 3-OH, iso-C15:0, C16:0, C16:1ω7c/ω6c, C18:0 and iso-C13:0 3-OH. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, three unidentified aminolipids and three unidentified polar lipids. Its low genome DNA G+C content, lack of an aminolipid and a difference in its substrate oxidation ability indicated that strain C51T should represent a new species. Furthermore, its distinct phylogeny, Shewanella-specific FISH probe SHEW227 mismatch, lower cellular G+C content and inability to produce menaquinones indicated that the C51T clade should represent a new genus in the Shewanellaceae, for which the name Parashewanella gen. nov. is proposed, the type species is Parashewanella spongiae comb. nov., and another species is Parashewanella curva sp. nov. The type strains of Parashewanella spongiae and Parashewanella curva are HJ039T (=KCTC 22492T=KCCM 42304T=JCM 13830T) and C51T (=MCCC 1K03463T=KCTC 62318T), respectively.

Histidinibacterium lentulum gen. nov., sp. nov., a marine bacterium from the culture broth of marine microalga Picochlorum sp. 122.

A Gram-stain-negative, non-spore-forming, aerobic, motile, ovoid or short rod shaped bacterium, designed strain B17T, was isolated from the culture broth of Picochlorum sp. 122. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain B17T forms a stable cluster with Oceanicolagranulosus MCCC 1A10589T (with the highest 16S rRNA gene similarity of 95.8 %) and Roseisalinusantarcticus DSM 11466T in the family Rhodobacteraceae. The only detected respiratory quinone was Q-10. The major cellular fatty acids were C18 : 1 ω7c/ω6c, C17 : 1iso I/anteiso B and C16 : 0. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid and two unidentified lipids. The genome G+C content was 69 mol%. Characteristics, such as a long lag phase, being motile with single polar flagellum, no aminolipid content, and little or no C18 : 1ω7c11-methyl and C19 : 0cyclo ω8c content could significantly distinguish strain B17T from its closely related type strains. Therefore strain B17T is suggested to represent a new species in a new genus, for which Histidinibacterium lentulum gen. nov., sp. nov. is proposed. The type strain B17T (=MCCC 1K03225T=KCTC 52553T).

The inhibitory activities and antiviral mechanism of Viola philippica aqueous extracts against grouper iridovirus infection in vitro and in vivo.

Grouper iridovirus (GIV) is one of the most serious pathogens in mariculture and causes high mortality rates in cultured groupers; then, effective medicines for controlling GIV infections are urgently needed. Viola philippica is a well-known medicinal plant, and the application of V. philippica aqueous extracts against GIV infection was assessed by different methods in this study. The results showed that the working concentration of V. philippica aqueous extracts was 10 mg/ml. V. philippica aqueous extracts below 10 mg/ml have no significant cytotoxic effects on cell viability, while extracts over 15 mg/ml decreased cell viability and showed cytotoxic activity. V. philippica aqueous extracts had excellent inhibitory effects against GIV infection in vitro and in vivo. The possible antiviral mechanism of V. philippica was further analysed, which indicated that V. philippica did no damages to GIV particles, but it could disturb GIV binding, entry and replication in host cells. V. philippica had the best inhibitory effects against GIV during viral infection stage of binding and replication in host cells. Overall, the results suggest that appropriate concentration of V. philippica aqueous extracts has great antiviral effects, making it an interesting candidate for developing effective medicines for preventing and controlling GIV infection in farmed groupers.

Selection and characterization of ssDNA aptamers specifically recognizing pathogenic Vibrio alginolyticus.

Vibrio alginolyticus (V. alginolyticus) is a major opportunistic pathogen to both marine animals and humans, which has also caused heavy economic losses to mariculture. The aim of this study was to develop highly specific aptamers for V. alginolyticus. Single-stranded DNA (ssDNA) aptamers with high binding affinity to viable V. alginolyticus were generated by Systematic Evolution of Ligands by Exponential Enrichment (SELEX) and identified by flow cytometric analysis in this study. The selected aptamers showed high specificity for V. alginolyticus and low apparent binding for other bacteria. The aptamers formed distinct stem-loop structures, which could form the basis of aptamers' specific binding to the target V. alginolyticus. Aptamer VA2 and VA8 showed particularly high binding affinity constant (Kd) of 14.31 ± 4.26 and 90.00 ± 13.51 nM, respectively. The aptamers produced no cytotoxic effects in vitro and in vivo. ssDNA aptamers were successfully selected against the viable bacteria pathogen V. alginolyticus by SELEX. The aptamers selected in this study could be not only applied as specific chemical molecular probes for studying V. alginolyticus pathogenesis to Trachinotus ovatus, but also developing rapid convenient diagnosis assay for V. alginolyticus infection, even when applied to the complex sample matrix, such as food and environment samples.

Motiliproteus coralliicola sp. nov., a bacterium isolated from coral.

A Gram-stain-negative, non-spore-forming, aerobic, motile, ovoid or rod-shaped bacterium, designated strain C34T, was isolated from a Porites species coral on Weizhou Island, China. Optimal growth occurred in 4 % NaCl (w/v), at 30 °C and pH 8. The only detected respiratory quinone was Q-8. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified ninhydrin-positive lipids, one ninhydrin-positive unidentified phospholipid and two unidentified polar lipids. The genome DNA G+C content was 56.7 mol%. The major cellular fatty acids were C16 : 1ω7c/iso-C15 : 0 2-OH, C16 : 0, C18 : 1ω7c/ω6c, C18 : 0 and iso-C11 : 0 3-OH. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain C34T forms a stable cluster with Motiliproteus sediminis CICC 10858T (with the highest sequence similarity of 95.7 %). Strain C34T was also physiologically and chemical taxonomically similar to M. sediminis CICC 10858T, although they could be distinguished by colony colour on 2216E agar, the flagellum position and the diphosphatidylglycerol content in the cellular polar lipid. Thus, strain C34T is suggested to represent a new species in the genus Motiliproteus, for which the name Motiliproteus coralliicola is proposed. The type strain is C34T (=MCCC 1K03462T=KCTC 62319T).