Functional and mechanistic studies of a phytogenic formulation, Shrimp Best, in growth performance and vibriosis in whiteleg shrimp.

Climate change and disease threaten shrimp farming. Here, we studied the beneficial properties of a phytogenic formulation, Shrimp Best (SB), in whiteleg shrimp. Functional studies showed that SB dose-dependently increased shrimp body weight and decreased feed conversion ratio. We found that SB protected against Vibrio parahaemolyticus as evidenced by survival rate, bacterial load, and hepatopancreatic pathology in shrimp. Finally, we explored the likely mechanism by which SB affects growth performance and vibriosis in shrimp. The 16S rRNA sequencing data showed that SB increased 6 probiotic genera and decreased 6 genera of pathogenic bacteria in shrimp. Among these, SB increased the proportion of Lactobacillus johnsonii and decreased that of V. parahaemolyticus in shrimp guts. To dissect the relationship among SB, Lactobacillus and Vibrio, we investigated the in vitro regulation of Lactobacillus and Vibrio by SB. SB at ≥ 0.25 µg/mL promoted L. johnsonii growth. Additionally, L. johnsonii and its supernatant could inhibit V. parahaemolyticus. Furthermore, SB could up-regulate five anti-Vibrio metabolites of L. johnsonii, which caused bacterial membrane destruction. In parallel, we identified 3 fatty acids as active compounds from SB. Overall, this work demonstrated that SB improved growth performance and vibriosis protection in shrimp via the regulation of gut microbiota.

Identification of toll-like receptor family and the immune function of new Sptlr-6 gene of Scylla paramamosain.

As a crucial member of pattern-recognition receptors (PRRs), the Tolls/Toll-like receptors (TLRs) gene family has been proven to be involved in innate immunity in crustaceans. In this study, nine members of TLR gene family were identified from the mud crab (Scylla paramamosain) transcriptome, and the structure and phylogeny of different SpTLRs were analyzed. It was found that different SpTLRs possessed three conserved structures in the TIR domain. Meanwhile, the expression patterns of different Sptlr genes in examined tissues detected by qRT-PCR had wide differences. Compared with other Sptlr genes, Sptlr-6 gene was significantly highly expressed in the hepatopancreas and less expressed in other tissues. Therefore, the function of Sptlr-6 was further investigated. The expression of the Sptlr-6 gene was up-regulated by Poly I: C, PGN stimulation and Vibrio parahaemolyticus infection. In addition, the silencing of Sptlr-6 in hepatopancreas mediated by RNAi technology resulted in the significant decrease of several conserved genes involved in innate immunity in mud crab after V. parahaemolyticus infection, including relish, myd88, dorsal, anti-lipopolysaccharide factor (ALF), anti-lipopolysaccharide factor 2 (ALF-2) and glycine-rich antimicrobial peptide (glyamp). This study provided new knowledge for the role of the Sptlr-6 gene in defense against V. parahaemolyticus infection in S. paramamosain.

Preparation of valine-curcumin conjugate and its in vitro antibacterial and antitumor activity and in vivo biological effects on American eels (Anguilla rostrata).

Curcumin (Cur) exhibits diverse natural pharmacological activities, despite its limited water solubility (hydrophobicity) and low bioavailability. In this investigation, a valine-curcumin conjugate (Val-Cur) was synthesized through amino acid side chain modification, and its solubility increased to 1.78 mg/mL. In vitro experimental findings demonstrated that the antibacterial activity of Val-Cur against Escherichia coli, Staphylococcus aureus, Aeromonas hydrophila, and Vibrio parahaemolyticus was significantly superior to that of Cur. The inhibition rate of Val-Cur against HepG2 (human hepatocellular carcinoma) cells was higher than that of Cur at low concentrations (below 25 µmol/L), although the IC50 value of Val-Cur did not differ significantly from that of Cur. In vivo biological effects of Val-Cur were assessed by adding it into the feed (150 mg/kg) of American eels (Anguilla rostrata). Val-Cur significantly improved the growth performance (↑weight gain rate, ↑specific growth rate, and ↓feed conversion rate) and activities of intestinal digestive enzymes (amylase and lipase) and antioxidant enzymes (superoxide dismutase) in American eels. Additionally, Val-Cur significantly improved serum biochemical indices (↑high-density lipoprotein cholesterol, ↓low-density lipoprotein cholesterol, ↓aspartate and alanine aminotransferases). Furthermore, Val-Cur increased intestinal microbial diversity, reduced the abundance of potentially pathogenic bacteria (Spiroplasma, Clostridium, and Pseudomonas), and elevated the abundance of beneficial digestion-promoting bacteria (Romboutsia, Phyllobacterium, Romboutsia sedimentorum, and Clostridium butyricum) conducive to glucose metabolism (P < 0.05). To the best of our knowledge, this study is the first to explore water-soluble curcumin in aquaculture, and the findings will lay the groundwork for the potential application of water-soluble curcumin in the field of aquaculture.

Identification and function analysis of BCL2 in immune response of Pteria penguin.

B-cell lymphoma/leukemia-2 (BCL2), an anti-apoptotic factor in the mitochondrial regulatory pathway of apoptosis, is critically important in immune defenses. In this study, a novel BCL2 gene was characterized from Pteria penguin (P. penguin). The PpBCL2 was 1482 bp long, containing an open reading frame (ORF) of 588 bp encoding 195 amino acids. Four highly conserved BCL-2 homology (BH) domains were found in PpBCL2. Amino acid alignment and phylogenetic tree showed that PpBCL2 had the highest similarity with BCL2 of Crassostrea gigas at 65.24 %. Tissue expression analysis showed that PpBCL2 had high constitutive expression in gill, digestive diverticulum and mantle, and was significantly increased 72 h of Vibrio parahaemolyticus (V. parahaemolyticus) challenge in these immune tissues. Furthermore, PpBCL2 silencing significantly inhibited antimicrobial activity of hemolymph supernatant by 1.4-fold, and significantly reduced the survival rate by 51.7 % at 72 h post infection in P. penguin. These data indicated that PpBCL2 played an important role in immune response of P. penguin against V. parahaemolyticus infection.

Isolation and characterization of an antimicrobial Bacillus subtilis strain O-741 against Vibrio parahaemolyticus.

Vibrio parahaemolyticus is a marine bacterium that can infect and cause the death of aquatic organisms. V. parahaemolyticus can also cause human foodborne infection via contaminated seafood, with clinical syndromes which include diarrhea, abdominal cramps, nausea and so on. Since controlling V. parahaemolyticus is important for aquaculture and human health, various strategies have been explored. This study investigates the application of antagonistic microorganisms to inhibit the growth of V. parahaemolyticus. We screened aquaculture environment samples and identified a Bacillus subtilis strain O-741 with potent antimicrobial activities. This strain showed a broad spectrum of antagonistic activities against V. parahaemolyticus and other Vibrio species. Application of the O-741 bacterium significantly increased the survival of Artemia nauplii which were infected with V. parahaemolyticus. Furthermore, the cell-free supernatant (CFS) of O-741 bacterium exhibited inhibitory ability against V. parahaemolyticus, and its activity was stable to heat, acidity, UV, enzymes, and organic solvents. Next, the O-741 CFS was extracted by ethyl acetate, and analyzed by ultra-performance liquid chromatography-mass-mass spectrometry (UPLC-MS/MS), and the functional faction was identified as an amicoumacin A compound. The organic extracts of CFS containing amicoumacin A had bactericidal effects on V. parahaemolyticus, and the treated V. parahaemolyticus cells showed disruption of the cell membrane and formation of cell cavities. These findings indicate that B. subtilis strain O-741 can inhibit the V. parahaemolyticus in vitro and in vivo, and has potential for use as a biocontrol agent for preventing V. parahaemolyticus infection.

Characterization of a secondary hydroxy-acyltransferase for lipid A in Vibrio parahaemolyticus.

Lipid A plays a crucial role in Vibrio parahaemolyticus. Previously we have reported the diversity of secondary acylation of lipid A in V. parahaemolyticus and four V. parahaemolyticus genes VP_RS08405, VP_RS01045, VP_RS12170, and VP_RS00880 exhibiting homology to the secondary acyltransferases in Escherichia coli. In this study, the gene VP_RS12170 was identified as a specific lipid A secondary hydroxy-acyltransferase responsible for transferring a 3-hydroxymyristate to the 2'-position of lipid A. Four E. coli mutant strains WHL00, WHM00, WH300, and WH001 were constructed, and they would synthesize lipid A with different structures due to the absence of genes encoding lipid A secondary acyltransferases or Kdo transferase. Then V. parahaemolyticus VP_RS12170 was overexpressed in W3110, WHL00, WHM00, WH300, and WH001, and lipid A was isolated from these strains and analyzed by using thin-layer chromatography and high-performance liquid chromatography-tandem mass spectrometry. The detailed structural changes of lipid A in these mutant strains with and without VP_RS12170 overexpression were compared and conclude that VP_RS12170 can specifically transfer a 3-hydroxymyristate to the 2'-position of lipid A. This study also demonstrated that the function of VP_RS12170 is Kdo-dependent and its favorite substrate is Kdo-lipid IVA. These findings give us better understanding the biosynthetic pathway and the structural diversity of V. parahaemolyticus lipid A.

Antibacterial and antibiofilm activity of halogenated phenylboronic acids against Vibrio parahaemolyticus and Vibrio harveyi.

Vibrios are associated with live seafood because they are part of the indigenous marine microflora. In Asia, foodborne infections caused by Vibrio spp. are common. In recent years, V. parahaemolyticus has become the leading cause of all reported food poisoning outbreaks. Therefore, the halogenated acid and its 33 derivatives were investigated for their antibacterial efficacy against V. parahaemolyticus. The compounds 3,5-diiodo-2-methoxyphenylboronic acid (DIMPBA) and 2-fluoro-5-iodophenylboronic acid (FIPBA) exhibited antibacterial and antibiofilm activity. DIMPBA and FIPBA had minimum inhibitory concentrations of 100 µg/mL for the planktonic cell growth and prevented biofilm formation in a dose-dependent manner. Both iodo-boric acids could diminish the several virulence factors influencing the motility, agglutination of fimbria, hydrophobicity, and indole synthesis. Consequently, these two active halogenated acids hampered the proliferation of the planktonic and biofilm cells. Moreover, these compounds have the potential to effectively inhibit the presence of biofilm formation on the surface of both squid and shrimp models.

Antibacterial and antibiofilm activities of iodinated hydrocarbons against Vibrio parahaemolyticus and Staphylococcus aureus.

Food-related illnesses have become a growing public concern due to their considerable socioeconomic and medical impacts. Vibrio parahaemolyticus and Staphylococcus aureus have been implicated as causative organisms of food-related infections and poisoning, and both can form biofilms which confer antibiotic resistance. Hence, the need for continuous search for compounds with antibiofilm and antivirulence properties. In this study, 22 iodinated hydrocarbons were screened for their antibiofilm activity, and of these, iodopropynyl butylcarbamate (IPBC) was found to effectively control biofilm formation of both pathogens with a MIC of 50 µg/mL which was bactericidal to V. parahaemolyticus and S. aureus. Microscopic studies confirmed IPBC inhibits biofilm formation of both bacteria and also disrupted their mixed biofilm formation. Furthermore, IPBC suppressed virulence activities such as motility and hemolytic activity of V. parahaemolyticus and the cell surface hydrophobicity of S. aureus. It exhibited a preservative potential against both pathogens in a shrimp model. IPBC disrupted the cell membrane of S. aureus and V. parahaemolyticus and differentially affected gene expressions related to biofilm formation and virulence. Additionally, it displayed broad-spectrum antibiofilm activities against other clinically relevant pathogens. These findings indicate IPBC offers a potential means of controlling infections mediated by Vibrio and Staphylococcus biofilms.

Epidemiological and Genomic analysis of Vibrio parahaemolyticus isolated from imported travelers at the port of Shanghai, China (2017-2019).

BACKGROUND: Vibrio parahaemolyticus is the predominant etiological agent of seafood-associated foodborne illnesses on a global scale. It is essential to elucidate the mechanisms by which this pathogen disseminates. Given the existing research predominantly concentrates on localized outbreaks, there is a pressing necessity for a comprehensive investigation to capture strains of V. parahaemolyticus cross borders. RESULTS: This study examined the frequency and genetic attributes of imported V. parahaemolyticus strains among travelers entering Shanghai Port, China, between 2017 and 2019.Through the collection of 21 strains from diverse countries and regions, Southeast Asia was pinpointed as a significant source for the emergence of V. parahaemolyticus. Phylogenetic analysis revealed clear delineation between strains originating from human and environmental sources, emphasizing that underlying genome data of foodborne pathogens is essential for environmental monitoring, food safety and early diagnosis of diseases. Furthermore, our study identified the presence of virulence genes (tdh and tlh) and approximately 120 antibiotic resistance-related genes in the majority of isolates, highlighting their crucial involvement in the pathogenesis of V. parahaemolyticus. CONCLUSIONS: This research enhanced our comprehension of the worldwide transmission of V. parahaemolyticus and its antimicrobial resistance patterns. The findings have important implications for public health interventions and antimicrobial stewardship strategies, underscoring the necessity for epidemiological surveillance of pathogen at international travel hubs.

Glycosaminoglycan lyase: A new competition between bacteria and the pacific white shrimp Litopenaeus vannamei.

Horizontal gene transfer (HGT) is an important evolutionary force in the formation of prokaryotic and eukaryotic genomes. In recent years, many HGT genes horizontally transferred from prokaryotes to eukaryotes have been reported, and most of them are present in arthropods. The Pacific white shrimp Litopenaeus vannamei, an important economic species of arthropod, has close relationships with bacteria, providing a platform for horizontal gene transfer (HGT). In this study, we analyzed bacteria-derived HGT based on a high-quality genome of L. vannamei via a homology search and phylogenetic analysis, and six HGT genes were identified. Among these six horizontally transferred genes, we found one gene (LOC113799989) that contains a bacterial chondroitinase AC structural domain and encodes an unknown glycosaminoglycan (GAG) lyase in L. vannamei. The real-time quantitative PCR results showed that the mRNA expression level of LOC113799989 was highest in the hepatopancreas and heart, and after stimulation by Vibrio parahaemolyticus, its mRNA expression level was rapidly up-regulated within 12 h. Furthermore, after injecting si-RNA and stimulation by V. parahaemolyticus, we found that the experimental group had a higher cumulative mortality rate in 48 h than the control group, indicating that the bacteria-derived GAG lyase can reduce the mortality of shrimp with respect to infection by V. parahaemolyticus and might be related to the resistance of shrimp to bacterial diseases. Our findings contribute to the study of the function of GAGs and provide new insights into GAG-related microbial pathogenesis and host defense mechanisms in arthropods.

Tracking Vibrio: population dynamics and ecology of Vibrio parahaemolyticus and V. vulnificus in an Alabama estuary.

Vibrio is a genus of halophilic, gram-negative bacteria found in estuaries around the globe. Integral parts of coastal cultures often involve contact with vectors of pathogenic Vibrio spp. (e.g., consuming raw shellfish). High rates of mortality from certain Vibrio spp. infections demonstrate the need for an improved understanding of Vibrio spp. dynamics in estuarine regions. Our study assessed meteorological, hydrographic, and biological correlates of Vibrio parahaemolyticus and V. vulnificus at 10 sites in the Eastern Mississippi Sound System (EMSS) from April to October 2019. During the sampling period, median abundances of V. parahaemolyticus and V. vulnificus were 2.31 log MPN/L and 2.90 log MPN/L, respectively. Vibrio spp. dynamics were largely driven by site-based variation, with sites closest to freshwater inputs having the highest abundances. The E-W wind scalar, which affects Ekman transport, was a novel Vibrio spp. correlate observed. A potential salinity effect on bacterial-particle associations was identified, where V. vulnificus was associated with larger particles in conditions outside of their optimal salinity. Additionally, V. vulnificus abundances were correlated to those of harmful algal species that did not dominate community chlorophyll. Correlates from this study may be used to inform the next iteration of regionally predictive Vibrio models and may lend additional insight to Vibrio spp. ecology in similar systems. IMPORTANCE: Vibrio spp. are bacteria found in estuaries worldwide; some species can cause illness and infections in humans. Relationships between Vibrio spp. abundance, salinity, and temperature are well documented, but correlations to other environmental parameters are less understood. This study identifies unique correlates (e.g., E-W wind scalar and harmful algal species) that could potentially inform the next iteration of predictive Vibrio models for the EMSS region. Additionally, these correlates may allow existing environmental monitoring efforts to be leveraged in providing data inputs for future Vibrio risk models. An observed correlation between salinity and V. vulnificus/particle-size associations suggests that predicted environmental changes may affect the abundance of Vibrio spp. in certain reservoirs, which may alter which vectors present the greatest vibrio risk.

Identification, diversity, and evolution analysis of Commd gene family in Haliotis discus hannai and immune response to biotic and abiotic stresses.

The Commd (Copper Metabolism gene MURR1 Domain) family genes play crucial roles in various biological processes, including copper and sodium transport regulation, NF-κB activity, and cell cycle progression. Their function in Haliotis discus hannai, however, remains unclear. This study focused on identifying and analyzing the Commd genes in H. discus hannai, including their gene structure, phylogenetic relationships, expression profiles, sequence diversity, and alternative splicing. The results revealed significant homology between H. discus hannai's Commd genes and those of other mollusks. Both transcriptome quantitative analysis and qRT-PCR demonstrated the responsiveness of these genes to heat stress and Vibrio parahaemolyticus infection. Notably, alternative splicing analysis revealed that COMMD2, COMMD4, COMMD5, and COMMD7 produce multiple alternative splice variants. Furthermore, sequence diversity analysis uncovered numerous missense mutations, specifically 9 in COMMD5 and 14 in COMMD10. These findings contribute to expanding knowledge on the function and evolution of the Commd gene family and underscore the potential role of COMMD in the innate immune response of H. discus hannai. This research, therefore, offers a novel perspective on the molecular mechanisms underpinning the involvement of Commd genes in innate immunity, paving the way for further explorations in this field.

Molecular characterization of a short-chained pentraxin gene from kuruma shrimp Marsupenaeus japonicus hemocytes.

Pentraxins (PTXs) are a family of pattern recognition proteins (PRPs) that play a role in pathogen recognition during infection via pathogen-associated molecular patterns (PAMPs). Here, we characterized a short-chained pentraxin isolated from kuruma shrimp (Marsupenaeus japonicus) hemocytes (MjPTX). MjPTX contains the pentraxin signature HxCxS/TWxS (where x can be any amino acid), although the second conserved residue of this signature differed slightly (L instead of C). In the phylogenetic analysis, MjPTX clustered closely with predicted sequences from crustaceans (shrimp, lobster, and crayfish) displaying high sequence identities exceeding 52.67 %. In contrast, MjPTX showed minimal sequence identity when compared to functionally similar proteins in other animals, with sequence identities ranging from 20.42 % (mouse) to 28.14 % (horseshoe crab). MjPTX mRNA transcript levels increased significantly after artificial infection with Vibrio parahaemolyticus (48 h), White Spot Syndrome Virus (72 h) and Yellow Head Virus (24 and 48 h). Assays done in vitro revealed that recombinant MjPTX (rMjPTX) has an ability to agglutinate Gram-negative and Gram-positive bacteria and to bind microbial polysaccharides and bacterial suspensions in the presence of Ca2+. Taken together, our results suggest that MjPTX functions as a classical pattern recognition protein in the presence of calcium ions, that is capable of binding to specific moieties present on the surface of microorganisms and facilitating their clearance.

Recent advances in understanding the fitness and survival mechanisms of Vibrio parahaemolyticus.

The presence of Vibrio parahaemolyticus (Vp) in different production stages of seafood has generated negative impacts on both public health and the sustainability of the industry. To further better investigate the fitness of Vp at the phenotypical level, a great number of studies have been conducted in recent years using plate counting methods. In the meantime, with the increasing accessibility of the next generation sequencing and the advances in analytical chemistry techniques, omics-oriented biotechnologies have further advanced our knowledge in the survival and virulence mechanisms of Vp at various molecular levels. These observations provide insights to guide the development of novel prevention and control strategies and benefit the monitoring and mitigation of food safety risks associated with Vp contamination. To timely capture these recent advances, this review firstly summarizes the most recent phenotypical level studies and provide insights about the survival of Vp under important in vitro stresses and on aquatic products. After that, molecular survival mechanisms of Vp at transcriptomic and proteomic levels are summarized and discussed. Looking forward, other newer omics-biotechnology such as metabolomics and secretomics show great potential to be used for confirming the cellular responses of Vp. Powerful data mining tools from the field of machine learning and artificial intelligence, that can better utilize the omics data and solve complex problems in the processing, analysis, and interpretation of omics data, will further improve our mechanistic understanding of Vp.

Genome-based characterization of a novel prophage of Vibrio parahaemolyticus, VPS05ph1, a novel member of Peduoviridae.

Vibrio parahaemolyticus is a globally important bacterium related to climate warming and health threat to human and marine animals. Yet, there is limited knowledge about its polylysogeny harboring multiple prophages and the genetic information. In this study, two prophages (VPS05ph1 and VPS05ph2) were identified in a V. parahaemolyticus isolate through genomic and transcriptional analyses. Both prophages were determined as HP1-like phages, located in a novel phylogenetic lineage of Peduoviridae. They shared a moderate genome-wide sequence similarity with each other and high synteny with the closest relatives, but showed low identities to the repressor counterparts of the representative phages within the family. In addition, no bacterial virulence genes, antibiotic resistance genes and known phage-encoded lytic proteins were identified on both prophage genomes. Moreover, the V. parahaemolyticus isolate was induced with mitomycin, which caused aberrant cellular morphology and nonviability of bacterial cells and excision of prophage VPS05ph1, accompanied by the respective inhibition and promotion of transcriptions of the cI-like and cox-like regulator genes for phage decision making. Results in this study provide the genetic context of polylysogeny in the V. parahaemolyticus isolate, support the diversity and prevalence of HP1-like phages in vibrios, and promote to explore interactions between the HP1-like prophage and its vibrio host.

Genome-wide identification of toll-like receptors in Octopus sinensis and expression analysis in response to different PAMPs stimulation.

Toll-like receptors (TLRs) are one of the extensively studied pattern recognition receptors (PRRs) and play crucial roles in the immune responses of vertebrates and invertebrates. In this study, 14 TLR genes were identified from the genome-wide data of Octopus sinensis. Protein structural domain analysis showed that most TLR proteins had three main structural domains: extracellular leucine-rich repeats (LRR), transmembrane structural domains, and intracellular Toll/IL-1 receptor domain (TIR). The results of subcellular localization prediction showed that the TLRs of O. sinensis were mainly located on the plasma membrane. The results of quantitative real-time PCR (qPCR) showed that the detected TLR genes were differentially expressed in the hemolymph, white bodies, hepatopancreas, gills, gill heart, intestine, kidney, and salivary gland of O. sinensis. Furthermore, the present study investigated the expression changes of O. sinensis TLR genes in hemolymph, white bodies, gills, and hepatopancreas in different phases (6 h, 12 h, 24 h, 48 h) after stimulation with PGN, poly(I: C) and Vibrio parahaemolyticus. The expression of most of the TLR genes was upregulated at different time points after infection with pathogens or stimulation with PAMPs, a few genes were unchanged or even down-regulated, and many of the TLR genes were much higher after V. parahaemolyticus infection than after PGN and poly(I:C) stimulation. The results of this study contribute to a better understanding of the molecular immune mechanisms of O. sinensis TLRs genes in resistance to pathogen stimulation.

Morinda citrifolia fruit extract enhances the resistance of Penaeus vannamei to Vibrio parahaemolyticus infection.

Vibrio parahaemolyticus is a gram-negative facultative anaerobic bacterium implicated as the causative agent of several shrimp diseases. As part of the effort to provide biocontrol and cost-effective treatments, this research was designed to elucidate the effect of Morinda citrifolia fruit extract on the immunity of Penaeus vannamei postlarvae (PL) to V. parahaemolyticus. The methanol extract of M. citrifolia was vacuum evaporated, and the bioactive compounds were detected using gas chromatography‒mass spectrometry (GC‒MS). Thereafter, P. vannamei PL diets were supplemented with M. citrifolia at different concentrations (0, 10, 20, 30, 40, and 50 mg/g) and administered for 30 days before 24 h of exposure to the bacterium V. parahaemolyticus. A total of 45 bioactive compounds were detected in the methanol extract of M. citrifolia, with cyclononasiloxane and octadecamethyl being the most abundant. The survival of P. vannamei PLs fed the extract supplement was better than that of the control group (7.1-26.7% survival greater than that of the control group) following V. parahaemolyticus infection. Shrimp fed 50 mg/g M. citrifolia had the highest recorded survival. The activities of digestive and antioxidant enzymes as well as hepatopancreatic cells were significantly reduced, except for those of lipase and hepatopancreatic E-cells, which increased following challenge with V. parahaemolyticus. Histological assessment of the hepatopancreas cells revealed reduced cell degeneration following the administration of the plant extracts (expecially those fed 50 mg/g M. citrifolia) compared to that in the control group. Therefore, the enhanced immunity against V. parahaemolyticus infection in P. vannamei could be associated with the improved hepatopancreas health associated with M. citrifolia fruit extract supplementation.

ZntA maintains zinc and cadmium homeostasis and promotes oxidative stress resistance and virulence in Vibrio parahaemolyticus.

Although metals are essential for life, they are toxic to bacteria in excessive amounts. Therefore, the maintenance of metal homeostasis is critical for bacterial physiology and pathogenesis. Vibrio parahaemolyticus is a significant food-borne pathogen that mainly causes acute gastroenteritis in humans and acute hepatopancreatic necrosis disease in shrimp. Herein, we report that ZntA functions as a zinc (Zn) and cadmium (Cd) homeostasis mechanism and contributes to oxidative stress resistance and virulence in V. parahaemolyticus. zntA is remarkably induced by Zn, copper, cobalt, nickel (Ni), and Cd, while ZntA promotes V. parahaemolyticus growth under excess Zn/Ni and Cd conditions via maintaining Zn and Cd homeostasis, respectively. The growth of ΔzntA was inhibited under iron (Fe)-restricted conditions, and the inhibition was associated with Zn homeostasis disturbance. Ferrous iron supplementation improved the growth of ΔzntA under excess Zn, Ni or Cd conditions. The resistance of ΔzntA to H2O2-induced oxidative stress also decreased, and its virulence was attenuated in zebrafish models. Quantitative real-time PCR, mutagenesis, and ß-galactosidase activity assays revealed that ZntR positively regulates zntA expression by binding to its promoter. Collectively, the ZntR-regulated ZntA is crucial for Zn and Cd homeostasis and contributes to oxidative stress resistance and virulence in V. parahaemolyticus.

Vibrio Species and Cyanobacteria: Understanding Their Association in Local Shrimp Farm Using Canonical Correspondence Analysis (CCA).

In aquatic environments, Vibrio and cyanobacteria establish varying relationships influenced by environmental factors. To investigate their association, this study spanned 5 months at a local shrimp farm, covering the shrimp larvae stocking cycle until harvesting. A total of 32 samples were collected from pond A (n = 6), pond B (n = 6), effluent (n = 10), and influent (n = 10). Vibrio species and cyanobacteria density were observed, and canonical correspondence analysis (CCA) assessed their correlation. CCA revealed a minor correlation (p = 0.847, 0.255, 0.288, and 0.304) between Vibrio and cyanobacteria in pond A, pond B, effluent, and influent water, respectively. Notably, Vibrio showed a stronger correlation with pH (6.14-7.64), while cyanobacteria correlated with pH, salinity (17.4-24 ppt), and temperature (30.8-31.5 °C), with salinity as the most influential factor. This suggests that factors beyond cyanobacteria influence Vibrio survival. Future research could explore species-specific relationships, regional dynamics, and multidimensional landscapes to better understand Vibrio-cyanobacteria connections. Managing water parameters may prove more efficient in controlling vibriosis in shrimp farms than targeting cyanobacterial populations.