Vibrio Populations Research Articles

Analysis on Bacterial Community of Noctiluca scintillans Algal Blooms Near Pingtan Island, China.

Noctiluca scintillans, known as a global red tide species, is a common red tide species found in Pingtan Island. To examine the bacterial community structure in different environments during the red tide period of N. scintillans on Pingtan Island, samples were collected from the Algal Bloom Area (ABA), Transition Area (TA), and Non-Algal Bloom Area (NBA) on 6 April 2022, and the environmental physicochemical factors and bacterial community were determined. The outbreak of N. scintillans red tide significantly impacted the water quality and bacterial community structure in the affected sea area. The water quality in the ABA has deteriorated markedly, with the contents of COD, NH4+-N, and PO43- in the ABA being significantly higher than those in the TA and NBA, while the pH is significantly lower than that in the TA and NBA. The richness, diversity, and evenness of the bacterial community in the ABA are all lower than those of the TA and NBA. For instance, the Shannon index values of the three sampling points are 4.41, 5.41, and 6.37, respectively. At the phylum level, the dominant bacterial phyla in the ABA are Proteobacteria, Firmicutes, and Cyanobacteria; in the TA, they are Proteobacteria, Bacteroidetes, and Firmicutes; and in the NBA, they are Proteobacteria, Bacteroidetes, and Cyanobacteria. At the genus level, the dominant bacterial genera in the ABA are Vibrio, Carnobacterium, Candidatus_Megaira, Planktomarina, and Pseudoalteromonas; in the TA, they are Vibrio, Planktomarina, Lentibacter, Glaciecola, and Jannaschia; and in the NBA, they are Planktomarina, Amylibacter, NS5_marine_group, Aurantivirga, and marine_metagenome. In the ABA, the combined proportion of Vibrio and Carnobacterium exceeds 50%, with Vibrio_splendidus accounting for 93% of the total Vibrio population. These research results can provide a scientific basis for clarifying the environmental characteristics and bacterial composition during the large-scale N. scintillans red tide in Pingtan Island.

Genetic Variation in the Atlantic Bobtail Squid-Vibrio Symbiosis From the Galician Rías.

Symbiotic marine bacteria that are transmitted through the environment are susceptible to abiotic factors (salinity, temperature, physical barriers) that can influence their ability to colonize their specific hosts. Given that many symbioses are driven by host specificity, environmentally transmitted symbionts are more susceptible to extrinsic factors depending on conditions over space and time. In order to determine whether the population structure of environmentally transmitted symbionts reflects host specificity or biogeography, we analysed the genetic structure of Sepiola atlantica (Cephalopoda: Sepiolidae) and their Vibrio symbionts (V. fischeri and V. logei) in four Galician Rías (Spain). This geographical location is characterized by a jagged coastline with a deep-sea entrance into the land, ideal for testing whether such population barriers exist due to genetic isolation. We used haplotype estimates combined with nested clade analysis to determine the genetic relatedness for both S. atlantica and Vibrio bacteria. Analyses of molecular variance (AMOVA) were used to estimate variation within and between populations for both host and symbiont genetic data. Our analyses reveal a low percentage of variation among and between host populations, suggesting that these populations are panmictic. In contrast, Vibrio symbiont populations show certain degree of genetic structure, demonstrating that the hydrology of the rías is driving bacterial distribution (and not host specificity). Thus, for environmentally transmitted symbioses such as the sepiolid squid-Vibrio association, abiotic factors can be a major selective force for determining population structure for one of the partners.

Diversity, virulence and antibiotic resistance of Vibrio Harveyi clade species associated with bivalve aquaculture within marine protected areas

The aim of the present study was to investigate the diversity, distribution of virulence factor genes and antimicrobial resistance phenotypes of Vibrio Harveyi clade species from two distinct and spatially distant near-shore bivalve farming environments located in protected marine reserves of the eastern Adriatic. Tissues of farmed Mediterranean mussel Mytilus galloprovincialis and European flat oyster Ostrea edulis, seawater and sediment samples were collected during six bi-monthly sampling events conducted over one year from farming locations in Lim Bay and Mali Ston Bay, Croatia. Eight distinctive Harveyi subclades, namely, V. harveyi, V. alginolyticus, V. diabolicus, V. jasicida, V. parahaemolyticus, V. rotiferianus, V. campbellii and V. communis, were detected by Phylogenetic Multilocus Sequence Analysis (MLSA) based on rpoD, toxR and rctB concatenated genes sequences. Genomic fingerprinting of MLSA-classified samples revealed substantial diversity of environmental isolates. The virulence-related genes considered typical for the Harveyi clade and their homologues were represented in all subclades with varying frequencies. Of twelve antibiotics commonly used in human and veterinary medicine, the most frequent resistance phenotypes were resistance to ampicillin (90%), erythromycin (39%), imipenem (29%) and streptomycin (22%). >60% of isolates were resistant to at least two classes of antibiotics. Seasonal or site-specific differences were found in the proportion of isolates carrying virulence genes and displaying specific antibiotic resistance phenotype.This study is the first to provide a broader perspective on the properties of Vibrio Harveyi clade species associated with ecosystems under presumably low anthropogenic pressures, such as marine protected areas. New data on virulence and antibiotic resistance are presented of Harveyi clade species coexisting in different environmental compartments, including those that have been largely overlooked or understudied in the context of bivalve aquaculture. Taken together, these results highlight the importance of monitoring the presence of potentially pathogenic strains in the natural Vibrio population of bivalve farming areas to reduce the risk to seafood consumers.

Effects of probiotic supplementary bioflocs (Rhodospirillum rubrum, Bacillus subtilis, Providencia rettgeri) on growth, immunity, and water quality in cultures of Pacific white shrimp (Litopenaeus vannamei)

Biofloc technology is a promising strategy for the super-intensive cultivation of Pacific white shrimp (Litopenaeus vannamei). However, conventional bioflocs originating from pre-existing systems have shown to be inferior to bioflocs with constant probiotic supplementation regarding the stability in yield. Hence we compared bioflocs supplemented with Rhodospirillum rubrum (RR), Bacillus subtilis (BS), and Providencia rettgeri (PR) to the clear water system (CT), in terms of growth performances, immune status, nitrogen substances, and Vibrio populations in cultures of L. vannamei together with microbial profiles in both the midgut and bioflocs. Our findings exhibited increased average daily gain (ADG) and protein efficiency ratio (PER) among shrimp reared in BS and PR while BS also reduced feed conversion ratio (FCR). Gene expression analyses of growth-related markers revealed an upregulation of amylase and peptide transporter 1 in shrimp of PR treatment, whilst the changes did not outperform the BS supplement in growth promotion. Furthermore, PR treatment was found to enhance the expression of immune-related genes toll-like receptor, prophenoloxidase (proPO), and heat shock protein 70 (hsp70). All biofloc treatments effectively reduced NO2-N level and mitigated Vibrio parahaemolyticus proliferation, particularly in the BS and PR groups. The redundant analysis illustrated shrimp growth closely associated with improved water quality instead of the expression of genes participating in digestion, absorption, or immunity. Moreover, microflora sequencing exhibited the supplemental probiotics altered microbial communities in bioflocs and gut, whereas they did not dominate in either environment. In spite of the discrepancies in microbial composition between bioflocs and midgut of shrimp, BS and PR treatments enriched Rhodobacteraceae populations in both environments. In summary, B. subtilis and P. rettgeri supplementary bioflocs promote L. vannamei growth through nutritional supplementation and water environment optimization. Supplementation of P. rettgeri will simultaneously enhance immune responses and stress resistance of L. vannamei via activating proPO cascade and upregulating hsp70. Given the apparent benefits of heterotrophic probiotic supplementary bioflocs, it is imperative to investigate more microbial species or their combinations that can stimulate bioflocs to produce more nutrients.

Probiotic potential of a novel endophytic Streptomyces griseorubens CIBA-NS1 isolated from Salicornia sp. against Vibrio campbellii infection in shrimp

A novel endophytic Streptomyces griseorubens CIBA-NS1 was isolated from a salt marsh plant Salicornia sp. The antagonistic effect of S. griseorubens against Vibrio campbellii, was studied both in vitro and in vivo. The strain was validated for its endophytic nature and characterized through scanning electron microscopy, morphological and biochemical studies and 16SrDNA sequencing. The salinity tolerance experiment has shown that highest antibacterial activity was at 40‰ (16 ± 1.4 mm) and lowest was at 10 ‰ salinity (6.94 ± 0.51 mm). In vivo exclusion of Vibrio by S. griseorubens CIBA-NS1 was studied in Penaeus indicus post larvae and evaluated for its ability to improve growth and survival of P. indicus. After 20 days administration of S. griseorubens CIBA-NS1, shrimps were challenged with V. campbellii. The S. griseorubens CIBA-NS1 reduced Vibrio population in test group when compared to control, improved survival (60.5 ± 6.4%) and growth, as indicated by weight gain (1.8 ± 0.05g). In control group survival and growth were 48.4 ± 3.5% and 1.4 ± 0.03 g respectively. On challenge with V. campbellii, the S. griseorubens CIBA-NS1 administered group showed better survival (85.6 ± 10%) than positive control (64.3 ± 10%). The results suggested that S. griseorubens CIBA-NS1 is antagonistic to V. campbellii, reduce Vibrio population in the culture system and improve growth and survival. This is the first report on antagonistic activity of S. griseorubens isolated from salt marsh plant Salicornia sp, as a probiotic candidate to prevent V. campbellii infection in shrimps.

Biological Function of Prophage-Related Gene Cluster ΔVpaChn25_RS25055~ΔVpaChn25_0714 of Vibrio parahaemolyticus CHN25.

Vibrio parahaemolyticus is the primary foodborne pathogen known to cause gastrointestinal infections in humans. Nevertheless, the molecular mechanisms of V. parahaemolyticus pathogenicity are not fully understood. Prophages carry virulence and antibiotic resistance genes commonly found in Vibrio populations, and they facilitate the spread of virulence and the emergence of pathogenic Vibrio strains. In this study, we characterized three such genes, VpaChn25_0713, VpaChn25_0714, and VpaChn25_RS25055, within the largest prophage gene cluster in V. parahaemolyticus CHN25. The deletion mutants ΔVpaChn25_RS25055, ΔVpaChn25_0713, ΔVpaChn25_0714, and ΔVpaChn25_RS25055-0713-0714 were derived with homologous recombination, and the complementary mutants ΔVpaChn25_0713-com, ΔVpaChn25_0714-com, ΔVpaChn25_RS25055-com, ΔVpaChn25_RS25055-0713-0714-com were also constructed. In the absence of the VpaChn25_RS25055, VpaChn25_0713, VpaChn25_0714, and VpaChn25_RS25055-0713-0714 genes, the mutants showed significant reductions in low-temperature survivability and biofilm formation (p < 0.001). The ΔVpaChn25_0713, ΔVpaChn25_RS25055, and ΔVpaChn25_RS25055-0713-0714 mutants were also significantly defective in swimming motility (p < 0.001). In the Caco-2 model, the above four mutants attenuated the cytotoxic effects of V. parahaemolyticus CHN25 on human intestinal epithelial cells (p < 0.01), especially the ΔVpaChn25_RS25055 and ΔVpaChn25_RS25055-0713-0714 mutants. Transcriptomic analysis showed that 15, 14, 8, and 11 metabolic pathways were changed in the ΔVpaChn25_RS25055, ΔVpaChn25_0713, ΔVpaChn25_0714, and ΔVpaChn25_RS25055-0713-0714 mutants, respectively. We labeled the VpaChn25_RS25055 gene with superfolder green fluorescent protein (sfGFP) and found it localized at both poles of the bacteria cell. In addition, we analyzed the evolutionary origins of the above genes. In summary, the prophage genes VpaChn25_0713, VpaChn25_0714, and VpaChn25_RS25055 enhance V. parahaemolyticus CHN25's survival in the environment and host. Our work improves the comprehension of the synergy between prophage-associated genes and the evolutionary process of V. parahaemolyticus.

Distribution and antibiotic resistance of vibrio population in an urbanized tropical lake-the Vembanad-in the southwest coast of India.

Among the diverse Vibrio spp. autochthonous to coastal ecosystems, V. cholerae, V. fluvialis, V. vulnificus and V. parahaemolyticus are pathogenic to humans. Increasing sea-surface temperature, sea-level rise and water-related disasters associated with climate change have been shown to influence the proliferation of these bacteria and change their geographic distribution. We investigated the spatio-temporal distribution of Vibrio spp. in a tropical lake for 1year at a 20-day interval. The abundance of Vibrio spp. was much higher during the south-west monsoon in 2018, when the lake experienced a once-in-a-century flood. The distribution of Vibrio spp. was influenced by salinity (r = 0.3, p < 0.001), phosphate (r = 0.18, p < 0.01) and nitrite (r = 0.16, p < 0.02) in the water. We isolated 470 colonies of Vibrio-like organisms and 341 could be revived further and identified using 16S rRNA gene sequencing. Functional annotations showed that all the 16 Vibrio spp. found in the lake could grow in association with animals. More than 60% of the isolates had multiple antibiotic resistance (MAR) index greater than 0.5. All isolates were resistant to erythromycin and cefepime. The proliferation of multiple antibiotic-resistant Vibrio spp. is a threat to human health. Our observations suggest that the presence of a diverse range of Vibrio spp. is favoured by the low-saline conditions brought about by heavy precipitation. Furthermore, infections caused by contact with Vibrio-contaminated waters may be difficult to cure due to their multiple antibiotic resistances. Therefore, continuous monitoring of bacterial pollution in the lakes is essential, as is the generation of risk maps of vibrio-infested waters to avoid public contact with contaminated waters and associated disease outbreaks.

Modelled microgravity impacts Vibrio fischeri population structure in a mutualistic association with an animal host.

Perturbations to host-microbe interactions, such as environmental stress, can alter and disrupt homeostasis. In this study, we examined the effects of a stressor, simulated microgravity, on beneficial bacteria behaviours when colonising their host. We studied the bacterium Vibrio fischeri, which establishes a mutualistic association in a symbiosis-specific organ within the bobtail squid, Euprymna scolopes. To elucidate how animal-microbe interactions are affected by the stress of microgravity, squid were inoculated with different bacterial strains exhibiting either a dominant- or sharing-colonisation behaviour in High Aspect Ratio Vessels, which simulate the low-shear environment of microgravity. The colonisation behaviours of the sharing and dominant strains under modelled microgravity conditions were determined by counting light-organ homogenate of squids as well as confocal microscopy to assess the partitioning of different strains within the light organ. The results indicated that although the colonisation behaviours of the strains did not change, the population levels of the sharing strains were at lower relative abundance in single-colonised animals exposed to modelled microgravity compared to unit gravity; in addition, there were shifts in the relative abundance of strains in co-colonised squids. Together these results suggest that the initiation of beneficial interactions between microbes and animals can be altered by environmental stress, such as simulated microgravity.

Cooperation and cheating orchestrate Vibrio assemblages and polymicrobial synergy in oysters infected with OsHV-1 virus.

Polymicrobial infections threaten the health of humans and animals but remain understudied in natural systems. We recently described the Pacific Oyster Mortality Syndrome (POMS), a polymicrobial disease affecting oyster production worldwide. In the French Atlantic coast, the disease involves coinfection with ostreid herpesvirus 1 (OsHV-1) and virulent Vibrio. However, it is unknown whether consistent Vibrio populations are associated with POMS in different regions, how Vibrio contribute to POMS, and how they interact with OsHV-1 during pathogenesis. By connecting field-based approaches in a Mediterranean ecosystem, laboratory infection assays and functional genomics, we uncovered a web of interdependencies that shape the structure and function of the POMS pathobiota. We show that Vibrio harveyi and Vibrio rotiferianus are predominant in OsHV-1-diseased oysters and that OsHV-1 drives the partition of the Vibrio community observed in the field. However only V. harveyi synergizes with OsHV-1 by promoting mutual growth and accelerating oyster death. V. harveyi shows high-virulence potential and dampens oyster cellular defenses through a type 3 secretion system, making oysters a more favorable niche for microbe colonization. In addition, V. harveyi produces a key siderophore called vibrioferrin. This important resource promotes the growth of V. rotiferianus, which cooccurs with V. harveyi in diseased oysters, and behaves as a cheater by benefiting from V. harveyi metabolite sharing. Our data show that cooperative behaviors contribute to synergy between bacterial and viral coinfecting partners. Additional cheating behaviors further shape the polymicrobial consortium. Controlling cooperative behaviors or countering their effects opens avenues for mitigating polymicrobial diseases.

Assessment of Vibrio populations in a transect of Rhizophora mangle in Punta Galeta, Panamá: culture-dependent analyses reveal biotechnological applications.

Rhizophora mangle is considered an ecological niche for microorganisms with potentially novel and complex degrading enzymes. To characterize Vibrio populations using culture-dependent methods, using samples collected from sediments and water along a red mangrove transect composed of three sites. Strains were characterized according to their distribution, capacity to degrade of organic matter and other environmental parameters. Additionally the sequence diversity was assessed using 16S rRNA sequencing. Bacterial densities were strongly associated with temperature and salinity. A total of 87 good-quality sequences representing the isolates from the three sites, were binned into eight OTUs (Operational taxonomic units). Taxonomic assignment indicated that the dominant members were Vibrionaceae. Beta diversity analyses showed that bacterial communities clustered by sample source rather than spatial distribution, and that alpha diversity was found to be higher in water than in sediment. Three percent of the strains from water samples could degrade carboxyl-methyl cellulose with the smallest enzymatic indexes compared to 4 % of the strains from sediment samples that showed the highest enzymatic indexes. Two strains identified as Vibrio agarivorans degraded cellulose and agarose, producing the highest enzymatic indexes. We found higher bacterial densities and diversity in the bacterial communities of the water samples compared to the sediment, with different OTUs including those similar to Ferrimonas, Providencia, or Shewanella which were not isolated in the sediment. Vibrio OTUs were shown to degrade cellulose in both sample types. The results of this study highlight the importance of red mangroves as Vibrio habitats and as reservoirs of potential enzyme sources with biotechnological applications.

The first reporting of prevalence Vibrio species and expression of HSP genes in rayed pearl oyster (Pinctada radiata) under thermal conditions.

The main goal of the present study was to evaluate the influence of thermal exposure on Vibrio population and HSP genes expression (HSP 90, HSP70, and HSP20) in rayed pearl oyster (P. radiata). To this end, the oysters were reared for 30 days at temperatures of 22°C (control), 25°C, 27°C, and 29°C. The results showed that five dominate Vibrio strains including Vibrio hepatarius, V. harveyi, V. alginolyticus, V. parahaemolyticus, and V. rotiferianus were identified. The highest population of V. parahaemolyticus, V. alginolyticus, and V. harveyi, was found in 29οC group. According to real-time PCR, mantle exhibited the highest expression levels of HSP20, HSP70, and HSP90 genes. A higher level of HSP20 expression was observed at high temperatures (25°C, 27°C, and 29°C) in the gonad and mantle compared to the control group (22°C) while decrease in HSP90 expression level was recorded in 25°C, 27°C, and 29°C groups. HSP20 expression level in adductor muscle was remarkably down-regulated in 27°C and 29°C groups. In this tissue, HSP70 was detected at highest levels in the 29οC group. In mantle, HSP90 gene expression was lowest at 22°C water temperature. Several Vibrio strains have been identified from pearl Gulf oyster that haven't been previously reported. The identification of dominant Vibrio species is essential for epidemiological management strategies to control and prevent Vibrio outbreaks in pearl oyster farms. The expression pattern of HSP genes differs in rayed pearl oyster tissues due to differences in their thermal tolerance capability and physiological and biological characteristics. The present study provides useful molecular information for the ecological adaptation of rayed pearl oysters after exposure to different temperature levels.

Environmental Factors Influencing Occurrence of Vibrio parahaemolyticus and Vibrio vulnificus.

Incidence of vibriosis is rising globally, with evidence that changing climatic conditions are influencing environmental factors that enhance growth of pathogenic Vibrio spp. in aquatic ecosystems. To determine the impact of environmental factors on occurrence of pathogenic Vibrio spp., samples were collected in the Chesapeake Bay, Maryland, during 2009 to 2012 and 2019 to 2022. Genetic markers for Vibrio vulnificus (vvhA) and Vibrio parahaemolyticus (tlh, tdh, and trh) were enumerated by direct plating and DNA colony hybridization. Results confirmed seasonality and environmental parameters as predictors. Water temperature showed a linear correlation with vvhA and tlh, and two critical thresholds were observed, an initial increase in detectable numbers (>15°C) and a second increase when maximum counts were recorded (>25°C). Temperature and pathogenic V. parahaemolyticus (tdh and trh) were not strongly correlated; however, the evidence showed that these organisms persist in oyster and sediment at colder temperatures. Salinity (10 to 15 ppt), total chlorophyll a (5 to 25 μg/L), dissolved oxygen (5 to 10 mg/L), and pH (8) were associated with increased abundance of vvhA and tlh. Importantly, a long-term increase in Vibrio spp. numbers was observed in water samples between the two collection periods, specifically at Tangier Sound (lower bay), with the evidence suggesting an extended seasonality for these bacteria in the area. Notably, tlh showed a mean positive increase that was ca. 3-fold overall, with the most significant increase observed during the fall. In conclusion, vibriosis continues to be a risk in the Chesapeake Bay region. A predictive intelligence system to assist decision makers, with respect to climate and human health, is warranted. IMPORTANCE The genus Vibrio includes pathogenic species that are naturally occurring in marine and estuarine environments globally. Routine monitoring for Vibrio species and environmental parameters influencing their incidence is critical to provide a warning system for the public when the risk of infection is high. In this study, occurrence of Vibrio parahaemolyticus and Vibrio vulnificus, both potential human pathogens, in Chesapeake Bay water, oysters, and sediment samples collected over a 13-year period was analyzed. The results provide a confirmation of environmental predictors for these bacteria, notably temperature, salinity, and total chlorophyll a, and their seasonality of occurrence. New findings refine environmental parameter thresholds of culturable Vibrio species and document a long-term increase in Vibrio populations in the Chesapeake Bay. This study provides a valuable foundation for development of predicative risk intelligence models for Vibrio incidence during climate change.

Allium-Derived Compound Propyl Propane Thiosulfonate (PTSO) Reduces Vibrio Populations and Increases Body Weight of European Seabass (Dicentrarchus labrax) Juveniles.

The global demand for fish products is continuously increasing as the population grows, and aquaculture plays an important role in supplying this demand. However, industrial antibiotic misuse has contributed to the spread of antimicrobial resistance among pathogenic bacteria, therefore, several antibiotic alternatives have been proposed. In this study, we have analyzed the effects of Allium-derived propyl propane thiosulfonate (PTSO) in European seabass juveniles' growth and performance. These effects were tested by measuring the body weight and analyzing the gut microbiome of fish after 89 days of feeding trial. The relative abundance of potentially pathogenic Vibrio in the foregut and hindgut of supplemented fish decreased, while Pseudomonas and Kocuria increased significantly. Alpha diversity indices significantly decreased in both gut regions of fish fed with Allium-derived PTSO supplemented diet, as well as between bacterial community composition. These results may indicate a positive effect of the supplementation in the diet with Allium-derived PTSO, reducing potentially pathogenic Vibrio and increasing body weight at the end of the experiment (89 days). However, this supplementation with Allium-derived PTSO produces changes in the diversity and composition of microbial communities, so further experiments would be necessary to explore bacterial community composition and health relationship.

Prevalence, Genomic Characterization, and Risk Assessment of Human Pathogenic Vibrio Species in Seafood

Pathogenic Vibrio species are largely responsible for human diseases associated with consumption of contaminated seafood. The aim of this study was to determine the prevalence, population densities, species diversity, and molecular characteristics of pathogenic Vibrio in various seafood commodities and the health risks associated with consumption of these contaminated commodities. Samples of finfish and shellfish (oysters and sea urchins) were collected from various regions and analyzed for Vibrio with the most-probable-number (MPN) technique. Genomic DNA of putative Vibrio isolates was analyzed by whole genome sequencing for taxonomic identification and identification of virulence and antimicrobial resistance genes. The risk of Vibrio-related illnesses due to the consumption of contaminated seafood was assessed with Risk Ranger. Populations of presumptive Vibrio were 2.6 to 4.4 log MPN/g and correlated with season; Vibrio levels were significantly higher (P < 0.05) in the summer. Fifteen Vibrio isolates were identified as Vibrio alginolyticus (five isolates), Vibrio parahaemolyticus (six isolates), Vibrio harveyi (two isolates), and Vibrio diabolicus (two isolates). Two of the six V. parahaemolyticus isolates (ST 2504 and ST 2505) from oysters harbored either the tdh gene for thermostable direct hemolysin or the trh gene for thermostable direct hemolysin-related hemolysin. In addition to virulence genes, the shellfish isolates also harbored genes encoding resistance to multiple antibiotics, including tetracycline, penicillin, quinolone, and β-lactams, thus arousing concern. The risk assessment predicted that an estimated 21 cases of V. parahaemolyticus-associated gastroenteritis could occur in the general population annually due to consumption of contaminated oysters. This study highlights both the wide prevalence and diversity of Vibrio in seafood and the potential for certain strains to threaten public health.

Characterization of Vibrio Populations from Cultured European Seabass and the Surrounding Marine Environment with Emphasis on V. anguillarum.

Vibrio species are widely distributed and can be potentially pathogenic to aquatic organisms. In this study, we isolated Vibrio spp. from environmental samples (seawater, sediment, and fish swabs) collected over a three-year period from a fish farm in Mali Ston Bay in the Adriatic Sea, Croatia, and assess their distribution. A total of 48 seawater samples and 12 sediment samples, as well as gill and skin swabs from 110 farmed European seabass, were analysed for the presence of Vibrio. Vibrio strains were identified to the species level by MALDI TOF MS. The analysis revealed that V. alginolyticus was the predominant species in European seabass, followed by V. anguillarum. V. alginolyticus was isolated from the sediments, along with V. gigantis and V. pomeroyi, while V. chagasii, V. cyclitrophicus, V. fortis, V. gigantis, V. harveyi, V. pelagius, and V. pomeroyi were isolated from seawater. V. anguillarum was isolated only twice during two different spring seasons, once from a diseased sea bass and the second time from a healthy sea bass. We analysed these two isolates and found that they differ both genetically and in terms of resistance to antibiotics. Our results confirm the seasonality of vibriosis incidence and the presence of the pathogenic V. anguillarum, which increases the risk of vibriosis.

Distinct dynamics of Vibrio parahaemolyticus populations in two farming models.

Despite the recent prosperity of shrimp cultivation in China, very little is known about how different shrimp farming models influence the dynamics of Vibrio parahaemolyticus populations and the antibiotic resistance of this bacterium. To this end, we conducted continuous surveillance of V. parahaemolyticus on four farms over 3years: two traditional shrimp farms with daily water exchange and two farms operated in the recirculating aquaculture systems (RAS). No antibiotics were used in these farms to exclude the potential impacts of antibiotics on the emergence of antibacterial resistance. Multilocus sequence typing was utilized to characterize the dynamics of V. parahaemolyticus populations. Whole-genome sequencing (WGS) was conducted to determine the representative sequence types (STs) at each farm. Results revealed that the population structure of V. parahaemolyticus remained stable over time in both RAS farms, with only nine and four STs observed at each. In contrast, annual replacement of V. parahaemolyticus populations was observed in traditional farms with 26 and 28 STs identified in rearing water. WGS of 50 isolates divided them into five clusters, of which ST917a isolates harboured a genomic island that disrupted the gene recA. Pair-wised genomic comparison of isolates from the same STs showed that they were genetically related but belonged to different clones associated with geographical distribution. These results suggested that RAS presented a specific ecological niche by minimizing the water exchanges with the external environment. In contrast, traditional farming might pose a food safety issue by introducing new V. parahaemolyticus populations with antibiotic resistance genes. Our results expose the potential food safety issue associated with conventional agriculture and should encourage the development of preventive strategies to reduce the emergence of resistant V. parahaemolyticus populations.

Population genetic and evolution analysis of Vibrio isolated from Turkish fish farms

The genus Vibrio includes important pathogenic species for human and aquatic organisms such as Vibrio cholera, V. parahaemolyticus, V. vulnificus, V. anguillarum or V. harveyi. At present, Vibrionaceae family consists of >190 described species, classified into nine genera. Vibrio are widespread in shellfish, finfish and marine ecosystems and show resourceful ecologies, which recognized as one of the most diverse bacterial groups for illuminating the genome evolution. In the present study, to clarify the relationship among aquatic species in the genus, a multilocus sequence analysis (MLSA) and typing (MLST) approach was applied to characterize 51 Vibrio isolates from Turkish fish farms, 146 strains deposited in the PubMLST database and 59 type strains from GenBank. For all studied isolates (n = 256), diversity analysis, population structure, determination of recombination, demographic history and gene flow were performed based on the MLST scheme. Vibrio isolates, subjected to the study, showed a high diversity within the Vibrio population and also genetic interactions into the genus. We found 17 new described sequence types by MLST analysis that were isolated from rainbow trout, sea bream and sea bass in Turkish fish farms, which clearly indicate that the genes underwent recombination frequently. While predominant sequence types were found in the presented study, differences of genotypes need to be evaluated in a disease situation or preventing measurements. The findings about genetic recombination possibly helps to understand differences of Vibrio infections in fish. Furthermore, elucidating of genetic variability within species shed light on providing effective measurements in aquaculture by vaccine production and drug applications.

Analysis of causes of changes in conditions of vannamei shrimp hepatopancreas indicators at PT. Lombang Sumber Rejeki Sumenep

Vannamei shrimp that are cultivated intensively require various steps to support the success of cultivation, one of which is observing the health condition of the shrimp. Shrimp health monitoring is carried out once every 10 days along with sampling activities. One of the parameters in shrimp health monitoring is a microscopic examination of the hepatopancreas using the wet preparation method. The indicators for determining the condition of the hepatopancreas organ that was observed microscopically were wrinkle, lipid, gregarine, necrosis, and microvilli whose results were expressed in percentage form. The purpose of this study was to determine the cause of changes in the condition of the hepatopancreas indicator which has an important role in the health of vannamei shrimp. This research was conducted in intensive ponds of PT. Lombang Sumber Rejeki which is located in Lombang Village, Batang - Batang District, Sumenep Regency. Data processing is done using Regression analysis. The peak increase in increase in the percentage of wrinkles occurred at the 4th sampling or the 40th DOC. Wrinkles increased in intensive ponds were significantly affected by lipid, microvilli, and gregarine conditions. Lipid indicators in hepatopancreas were significantly influenced by the type and amount of feed-in shrimp. Vibrio population combined with the average daily feeding can significantly affect the gregarine population. The microvilli are affected by the incidence of necrosis in the hepatopancreas tubules, the cause of the necrosis is thought to be due to factors other than the Vibrio population in the hepatopancreas.

Cholera in Haiti

The cholera epidemic that hit Haiti from October 2010 to February 2019 was the world's deadliest of the last 25 years. Officially, the successive waves caused 9789 deaths, although numerous additional casualties could not be recorded. The origin of this epidemic has been the subject of a controversy involving two opposing theories. The first hypothesis, put forward by renowned American academics, was that the cholera epidemic originated from the environment, due to the proliferation and transmission of aquatic Vibrio cholerae bacteria driven by a confluence of circumstances, i.e., the earthquake followed by a hot summer and, ultimately, heavy rainfall and flooding. The alternative hypothesis, which was subsequently confirmed by epidemiological and genomic studies, attributed the epidemic to the recent importation of cholera by UN peacekeepers recently arrived from Nepal, and to a river polluted with sewage. In late 2016, the Secretary General of the United Nations finally begged the Haitian people for forgiveness. This implicit recognition of the role of the UN in the cholera epidemic helped to fund the ongoing fight against it. Case-area targeted interventions aimed at interrupting cholera transmission were reinforced, which resulted in the extinction of the epidemic within two years. In the meantime, several phylogenetic studies on Vibrio cholerae during the seventh cholera pandemic demonstrated that local environmental and global epidemic Vibrio populations were distinct. These studies also showed that epidemics arose when the bacterium had diversified and that it had spread during transmission events associated with human travel.

Diversity and fluctuation of cultivable Vibrio bacteria populations in an integrated multi-trophic aquaculture (IMTA) system of Holothuria scabra, Chanos chanos and Gracillaria sp

Sea cucumber is one of the vital aquaculture commodities in the global market. Progressive demand and limiting the supply of sea cucumber from natural sources drove sea cucumber aquaculture development. An integrated multi-trophic aquaculture system (IMTA) was a polyculture system in aquaculture to improve production by promoting nutrient utilisation through different tropical levels. This system combined sea cucumber (Holothuria scabra), milkfish (Chanos chanos), and seaweed (Gracillaria sp.) in a rearing tank system. Several factors affect the success of IMTA processes, including microorganisms. Microorganisms in the aquaculture environment play a crucial role in elements cycling, energy flow and farmed-species health. Diseases caused by the bacteria, mainly from the Vibrionaceae family, were often chronic than acute and may cause a high mortality percentage. This study aimed to investigate the Vibrio bacterial diversity and fluctuation in the water of IMTA rearing tanks. The result indicated that the Vibrio bacterial diversity from the polyculture system (IMTA) was generally higher than the monoculture system. Vibrio bacteria populations from different culture systems have been found to consist of varied bacterial species. However, the predominant species was the same. The polyculture system is suggested as a sustainable and eco-friendly culture system.