Vibrio Campbellii Research Articles

Amphi-enterobactin commonly produced among Vibrio campbellii and Vibrio harveyi strains can be taken up by a novel outer membrane protein FapA that also can transport canonical Fe(III)-enterobactin.

Vibrio campbellii BAA-1116 (formerly Vibrio harveyi) is a model organism for quorum sensing study and produces the siderophores anguibactin and amphi-enterobactin. This study examined the mechanisms and specificity of siderophore uptake in V. campbellii and V. harveyi, and surveyed the diversity of siderophore production in V. campbellii and V. harveyi strains. The amphi-enterobactin gene cluster of BAA-1116 harbors a gene, named fapA, that is a homologue of genes encoding Fe(III)-siderophore-specific outer membrane receptors. Another strain, V. campbellii HY01, a strain pathogenic to shrimp, also carries this cluster including fapA. Our siderophore bioassay results using HY01-derived indicator strains show that the FapA protein localized in the outer membrane fraction of V. campbellii HY01 is essential for the uptake of Fe(III)-amphi-enterobactin as well as exogenous siderophores, including enterobactin from E. coli, but not vanchrobactin from V. anguillarum RV22 while Fe(III)-amphi-enterobactin can be utilized by V. anguillarum. Electrospray ionization mass spectrometry as well as bioassay revealed that various V. campbellii and V. harveyi strains produce a suite of amphi-enterobactins with various fatty acid appendages, including several novel amphi-enterobactins, and these amphi-enterobactins can be taken up by V. campbellii HY01 via FapA, indicating that amphi-enterobactin production is a common phenotype among V. campbellii and V. harveyi, whereas our previous work, confirmed herein, showed that anguibactin is only produced by V. campbellii strains. These results along with the additional finding that a 2,3-dihydroxybenzoic acid biosynthesis gene, aebA, located in the amphi-enterobactin gene cluster, is essential for both anguibactin and amphi-enterobactin biosynthesis, suggest the possibility that amphi-enterobactin is a native siderophore of V. campbellii and V. harveyi, while the anguibactin system has been acquired by V. campbellii during evolution.

PirA & B toxins discovered in archived shrimp pathogenic Vibrio campbellii isolated long before EMS/AHPND outbreaks

Toxins PirvpA and PirvpB were first described in 2014 from Vibrio parahaemolyticus (VP) isolates discovered in 2013 as the cause of acute hepatopancreatic necrosis disease (AHPND) that emerged as a new disease of Chinese cultivated shrimp in 2009. It was subsequently reported from Thailand in 2012. By using PirvpA and PirvpB specific monoclonal antibodies (MAbs) together with reference VPAHPND isolates to screen archived bacterial cultures, we discovered 3 isolates of Vibrio (previously identified as V. harveyi) including VH 639, VH 1526 and VH Surat that were positive for both PirA and PirB toxins, even though the isolates were collected in Thailand over 10 years prior to reported Thai AHPND outbreaks. Western blot analysis revealed that the PirA/B toxins from these Vibrio isolates matched the molecular masses of the PirvpA/B toxins of previously described VPAHPND isolates. PCR analysis using VPAHPND detection methods that target the PirvpA and PirvpB toxin genes (AP4 and TUMSAT-Vp3) gave amplicons of the expected size from the 3 Vibrio isolates, and sequence analysis of the amplicons revealed 99% identity with the sequences of the PirvpA and PirvpB genes of previously described VPAHPND isolates. Pathogenicity tests performed by reverse gavage and immersion challenge tests demonstrated the pattern of AHPND pathology. Species confirmation of these 3 Vibrio isolates by multilocus sequence analysis (MLSA) of 16S rRNA, rpoD, rctB, and toxR genes revealed that they belong to V. campbellii clade. The results revealed that V. campbellii isolates capable of producing PirA and PirB toxins were present in Thailand up to 7 years before AHPND was reported from China and up to a decade before it was reported from Thailand. The plasmid or chromosomal location of the PirA and PirB toxin genes in these archived V. campbellii isolates and their phylogenetic relationship to current VPAHPND isolates are being determined.

Complete Genome Sequences of Two Bioluminescent Vibrio campbellii Strains Isolated from Biofouling Communities in the Bay of Bengal.

ABSTRACTVibrio campbellii is a pathogen of aquatic animals and has been proposed as a bacterial partner in the formation of bioluminescent milky seas. We present here the complete genome sequences assembled from Illumina and Oxford Nanopore data for two bioluminescent Vibrio campbellii strains (BoB-53 and BoB-90) isolated from biofouled moorings in the Bay of Bengal.

Phylogenetic Analysis of Atypical Hemolysin Gene in Vibrio campbellii and Effects of Cultivation Salinity and pH on Hemolytic Activity and Virulence

The purposes of this study were to analyze the atypical hemolysin gene of V. campbellii isolates, and to evaluate the effects of cultivation salinity (0.5, 1.5, and 3.0 % NaCl) and pH (5.0, 7.3, and 8.6) on the hemolytic activity and virulence of V. campbellii. Phylogenetic analysis of atypical hemolysin gene sequences obtained from V. campbellii demonstrated 84 - 85 % identity with the hlyA of V. cholerae. V. campbellii grown at 1.5 or 3.0 % NaCl, which exhibited significant higher hemolytic activity compared to those previously grown at 0.5 % NaCl. Maximum hemolytic activity was observed among acid-adapted V. campbellii which was previously grown at pH 5.0 for 5 h. Likewise, its virulence against Galleria mellonella was enhanced (~20 times) in comparison to that of non-adapted V. campbellii. Based on our results, it seems that V. campbellii might have acquired hemolysin gene from V. cholerae. Moreover, both cultivation salinity and pH are deemed important for the hemolytic activity and virulence of V. campbellii. This will be useful for the environmental control of this pathogen in aquaculture.

A Case Report on the Survivability of Marine Luminous Bacteria Vibrio campbellii STF1 under Starvation Conditions

Recently luminous Vibrio campbellii has been recognised as a cosmopolitan pathogen in seafood and aquaculture industry. The significance of this study is to present the findings derived from longer-term starvation experiment on intense luminescence producing bacteria Vibrio campbellii strain STF1. This strain was isolated from surface swab of Synanceia verrucosa (stone fish) and subjected to the starvation-survival procedure. The viability rate of this culture was determined following spread plate method by counting viable cells in starter inoculum and in the same starvation culture. It was observed that 90 to 95% of luminous bacteria could remain viable for over 4 years under nutrient deficiency condition. This study also determines the effectiveness of the preservation of luminous bacteria in sterile sweater.

High amorphous poly-beta-hydroxybutyrate (PHB) content in a probiotic Bacillus strain displays better protective effects in Vibrio-challenged gnotobiotic Artemia

In this study, the Bacillus sp. JL47, a superior PHB-accumulating Bacillus strain identified from the previous work, was tested for its protective effects in gnotobiotic Artemia franciscana during a pathogenic Vibrio campbellii challenge. The utilization of gnotobiotic Artemia is important in this experiment because any possible microbial interference (which are naturally present in conventional culture system) are eliminated in this model culture system, hence the interpretation of the results in this mechanistic study can be more conclusive. The survival of the Artemia fed the Bacillus sp. JL47 at 1×107cellsmL−1 was significantly higher as compared with the challenged control and the survival was almost doubled when the dose was increased to 5×107cellsmL−1. However, feeding the Artemia at 106cellsmL−1 or lower showed no significant protective effects. Based on these densities, the estimated concentration of amorphous PHB showing a significant protection in Artemia was c. 2.44mgL−1 and the effects were even better when the amorphous PHB level was increased to 12.19mgL−1. Furthermore, feeding Bacillus sp. JL47 containing 55% amorphous PHB (on CDW) to Artemia showed a significantly higher survival in a Vibrio challenge relative to Bacillus containing 29% PHB. The data suggest that the amorphous PHB accumulated in the Bacillus sp. JL47 strain is an important determinant for the increased survival of challenged Artemia.

Bacterial Succession on Sinking Particles in the Ocean's Interior.

Sinking particles formed in the photic zone and moving vertically through the water column are a main mechanism for nutrient transport to the deep ocean, and a key component of the biological carbon pump. The particles appear to be processed by a microbial community substantially different from the surrounding waters. Single cell genomics and metagenomics were employed to describe the succession of dominant bacterial groups during particle processing. Sinking particles were extracted from sediment traps at Station Aloha in the North Pacific Subtropical Gyre (NPSG) during two different trap deployments conducted in July and August 2012. The microbial communities in poisoned vs. live sediment traps differed significantly from one another, consistent with prior observations by Fontanez et al. (2015). Partial genomes from these communities were sequenced from cells belonging to the genus Arcobacter (commensalists potentially associated with protists such as Radiolaria), and Vibrio campbellii (a group previously reported to be associated with crustacea). These bacteria were found in the particle-associated communities at specific depths in both trap deployments, presumably due to their specific host-associations. Partial genomes were also sequenced from cells belonging to Idiomarina and Kangiella that were enriched in live traps over a broad depth range, that represented a motile copiotroph and a putatively non-motile algicidal saprophyte, respectively. Planktonic bacterial cells most likely caught in the wake of the particles belonging to Actinomarina and the SAR11 clade were also sequenced. Our results suggest that similar groups of eukaryote-associated bacteria are consistently found on sinking particles at different times, and that particle remineralization involves specific, reproducible bacterial succession events in oligotrophic ocean waters.

Cytotoxic and Antibacterial Compounds from the Coral-Derived Fungus Aspergillus tritici SP2-8-1.

Three novel compounds, 4-methyl-candidusin A (1), aspetritone A (2) and aspetritone B (3), were obtained from the culture of a coral-derived fungus Aspergillus tritici SP2-8-1, together with fifteen known compounds (4–18). Their structures, including absolute configurations, were assigned based on NMR, MS, and time-dependent density functional theory (TD-DFT) ECD calculations. Compounds 2 and 5 exhibited better activities against methicillin-resistant strains of S. aureus (MRSA) ATCC 43300 and MRSA CGMCC 1.12409 than the positive control chloramphenicol. Compound 5 displayed stronger anti-MRSA and lower cytotoxic activities than 2, and showed stronger antibacterial activities against strains of Vibrio vulnificus, Vibrio rotiferianus, and Vibrio campbellii than the other compounds. Compounds 2 and 10 exhibited significantly stronger cytotoxic activities against human cancer cell lines HeLa, A549, and Hep G2 than the other compounds. Preliminary structure–activity relationship studies indicated that prenylation of terphenyllin or candidusin and the tetrahydrobenzene moiety in anthraquinone derivatives may influence their bioactivity.

Complete Genome Sequence of Vibrio campbellii LMB 29 Isolated from Red Drum with Four Native Megaplasmids

Vibrio spp. are the most common pathogens for animals reared in aquaculture. Vibrio campbellii, which is often involved in shrimp, fish and mollusks diseases, is widely distributed in the marine environment worldwide, but our knowledge about its pathogenesis and antimicrobial resistance is very limited. The existence of this knowledge gap is at least partially because that V. campbellii was originally classified as Vibrio harveyi, and the detailed information of its comparative genome analysis to other Vibrio spp. is currently lacking. In this study, the complete genome of a V. campbellii predominant strain, LMB29, was determined by MiSeq in conjunction with PacBio SMRT sequencing. This genome consists of two circular DNA chromosomes and four megaplasmids. Comparative genome analysis indicates that LMB29 shares a 96.66% similarity (average nucleotide identity) with the V. campbellii ATCC strain BAA-1116 based on a 75% AF (average fraction) calculations, and its functional profile is very similar to V. campbellii E1 and V. campbellii CAIM115. Both type III secretion system (T3SS) and type VI secretion system (T6SS), along with the tlh gene which encodes a thermolabile hemolysin, are present in LMB29 which may contribute to the bacterial pathogenesis. The virulence of this strain was experimental confirmed by performing a LDH assay on a fish cell infection model, and cell death was observed as early as within 3 h post infection. Thirty-seven antimicrobial resistance genes (>45% identity) were predicted in LMB29 which includes a novel rifampicin ADP ribosyltransferase, arr-9, in plasmid pLMB157. The gene arr-9 was predicted on a genomic island with horizontal transferable potentials which may facilitate the rifampicin resistance dissemination. Future researches are needed to explore the pathogenesis of V. campbellii LMB29, but the availability of this genome sequence will certainly aid as a basis for further analysis.

Complete Genome Sequence of Acute Hepatopancreatic Necrosis Disease-Causing Vibrio campbellii LA16-V1, Isolated from Penaeus vannamei Cultured in a Latin American Country.

ABSTRACTWe report here the complete genome sequence of Vibrio campbellii, isolated from Penaeus vannamei cultured in a Latin American country. The Tn3-like transposon and pirAB genes were encoded on the plasmid pLA16-2. These data support the geographical variations in the virulence plasmid found among acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio isolates from Latin America and Asia.

A probiotic Bacillus strain containing amorphous poly-beta-hydroxybutyrate (PHB) stimulates the innate immune response of Penaeus monodon postlarvae

In this study, the PHB-accumulating Bacillus sp. JL47 strain (capable of accumulating 55% PHB on cell dry weight) was investigated for its effects on the immune response of giant tiger shrimp (Penaeus monodon) postlarvae (PL) before and after the Vibrio campbellii challenge. Briefly, shrimp PL were cultured and fed with Artemia nauplii enriched with Bacillus sp. JL47. Shrimp receiving the Artemia nauplii without JL47 enrichment were used as control. After 15 days of feeding, the shrimp were challenged with pathogenic V. campbellii LMG 21363 at 106 cells mL−1 by immersion. Relative expression of the immune related genes encoding for prophenoloxidase (proPO), transglutaminase (TGase) and heat shock protein 70 (Hsp70) in the shrimp were measured before (0 h) and after (3, 6, 9, 12, 24 h) the Vibrio challenge by quantitative real-time PCR using β-actin as the reference gene. The expressions of TGase and proPO were significantly up-regulated (p < 0.05) within 9 h and 12 h, respectively after challenge in shrimp receiving the Bacillus sp. JL47 as compared to the challenged and non-challenged controls. Hsp70 expression was significantly increased (p < 0.05) at 3 h post-challenge in all challenged shrimp. Interestingly, proPO and TGase genes were significantly up-regulated (p < 0.05) in Bacillus sp. JL47 treated shrimp even before the Vibrio challenge was applied. No up-regulation in the Hsp70 gene, however, was observed under these conditions. The data suggest that the protective effect of the PHB-accumulating Bacillus sp. JL47 in shrimp was due to its capacity to stimulate the innate immune related genes of the shrimp, specifically the proPO and TGase genes. The application of probiotic Bacillus species, capable of accumulating a significant amount of PHB, is suggested as potential immunostimulatory strategy for aquaculture.

Capacity of cationic and anionic porphyrins to inactivate the potential aquaculture pathogen Vibrio campbellii

Photodynamic Antimicrobial Chemotherapy (PACT) has emerged as a promising method for pathogen eradication and control. PACT uses light excitation of non-toxic photosensitisers to produce singlet oxygen (1O2), which in turn damages and eradicates microbial cells. In the present study, a naturally luminescent Vibrio campbellii strain ISO7 (V. campbellii ISO7) was used as a model aquaculture pathogen to test the suitability of two porphyrin compounds, the tetra-cationic TMPyP and the tetra-anionic TPPS4, for the treatment of aquaculture water. Initial work accurately identified the bacterial strain and confirmed its virulence towards giant tiger prawns Penaeus monodon when injected. The strain killed 100% of injected prawns within 1 to 16h, while control prawns injected with sterile buffer remained healthy. Koch's postulates were satisfied by identification of re-isolated strains by multiplex PCR and sequencing of housekeeping genes. In separate time-course experiments, the two photosensitisers were diluted in aquaculture water seeded with the indicator bacterium and samples were irradiated for 24h using 150W white LED light. Luminescence assays, growth and regrowth experiments demonstrated that the cytotoxicity of generated 1O2 was both time- and dose-dependent, and confirmed that light or porphyrins alone were not toxic. Continuous irradiation in the presence of 20μM cationic porphyrin for 5h or 1μM for 24h achieved complete lethality of the indicator bacterium. Consistent with previous reports, the tested anionic porphyrin did not impact on the survival of the bacterium, causing only a slight decline in the luminescence signal. Photo-bleaching tests demonstrated natural degradation of both porphyrins after continuous irradiation, making them suitable as ‘self-destructive’ photosensitizers for in situ treatment of aquaculture waters, as they do not accumulate in the water.

The impact of catecholamine sensing on the virulence of Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (AHPND)

Acute hepatopancreatic necrosis disease (AHPND) is a severe shrimp disease that causes significant losses in the shrimp industry worldwide. In 2013, specific strains of Vibrio parahaemolyticus were found to be responsible for AHPND. Recently, inhibiting the detection of catecholamines has been reported to decrease the virulence of various pathogenic bacteria, including Vibrio anguillarum, Vibrio campbellii and human pathogenic Vibrio parahaemolyticus. Thus, in this study we investigated whether catecholamine sensing has any effect on the virulence of an AHPND-causing V. parahaemolyticus strain isolated from outbreaks in Vietnam. We found that the catecholamines norepinephrine and dopamine (50μM) increased motility of V. parahaemolyticus (P<0.05). Further, the catecholamine-induced motility could be neutralized by the prokaryotic catecholamine receptor antagonist LED209. Finally, pre-treatment of V. parahaemolyticus with catecholamines significantly increased its virulence to whiteleg shrimp (Penaeus vannamei), and pretreatment with the antagonist LED209 neutralized this effect (P<0.05). LED209 increased the survival of shrimp challenged with catecholamine-pretreated V. parahaemolyticus to levels that were even higher than those observed in shrimp challenged with untreated V. parahaemolyticus, suggesting that this type of compounds might be useful to decrease losses due to AHPND in shrimp.

Knockdown of heat shock protein 70 (Hsp70) by RNAi reduces the tolerance of Artemia franciscana nauplii to heat and bacterial infection

RNA interference (RNAi) was used to assess the role of the molecular chaperone Hsp70 in protecting nauplii of the crustacean, Artemia franciscana, against abiotic and biotic stressors. As revealed respectively by RT-PCR and immunoprobing of Western blots, the injection of A. franciscana females with Hsp70 dsRNA eliminated Hsp70 mRNA and protein in nauplii released from these animals. The loss of Hsp70 had no apparent effect on either embryo development or the viability of A. franciscana nauplii. The survival of nauplii lacking Hsp70, as compared to those containing the Hsp, was reduced 41% by heat stress and 34% upon Vibrio campbellii infection. A role for Hsp70 in protecting A. franciscana nauplii against heat stress and bacterial infection was demonstrated for the first time by using RNAi to knock down the protein. The results suggest that Hsp70 assisted in maintaining protein homeostasis within stressed cells while potentially stimulating the innate immune system of A. franciscana. Information of the type generated in this work has potential for application in the culture of A. franciscana and other commercially important aquatic invertebrates.

Effect of 4-nonylphenol on the immune response of the Pacific oyster Crassostrea gigas following bacterial infection with Vibrio campbellii

The xenoestrogen 4-nonylphenol (NP) is a ubiquitous aquatic pollutant and has been shown to impair reproduction, development, growth and, more recently, immune function in marine invertebrates. We investigated the effects of short-term (7 d) exposure to low (2 μg l−1) and high (100 μg l−1) levels of NP on cellular and humoral elements of the innate immune response of Crassostrea gigas to a bacterial challenge. To this end, we measured 1) total hemocyte counts (THC), 2) relative transcript abundance of ten immune-related genes (defh1, defh2, bigdef1, bigdef2, bpi, lysozyme-1, galectin, C-type lectin 2, timp, and transglutaminase) in the hemocytes, gill and mantle, and 3) hemolymph plasma lysozyme activity, following experimental Vibrio campbellii infection. Both low and high levels of NP were found to repress a bacteria-induced increase in THC observed in the control oysters. While several genes were differentially expressed following bacterial introduction (bigdef2, bpi, lysozyme-1, timp, transglutaminase), only two genes (bpi in the hemocytes, transglutaminase in the mantle) exhibited a different bacteria-induced expression profile following NP exposure, relative to the control oysters. Independently of infection-status, exposure to NP also altered mRNA transcript abundance of several genes (bpi, galectin, C-type lectin 2) in naïve, saline-injected oysters. Finally, plasma lysozyme activity levels were significantly higher in low dose NP-treated oysters (both naïve and bacteria challenged) relative to control oysters. Combined, these results suggest that exposure to ecologically-relevant (low) and extreme (high) levels of NP can alter both cellular and humoral elements of the innate immune response in C. gigas, an aquaculture species of global economic importance.

Degradation intermediates of polyhydroxy butyrate inhibits phenotypic expression of virulence factors and biofilm formation in luminescent Vibrio sp. PUGSK8.

Luminescent vibrios are ubiquitous in the marine environment and are the causative agents of vibriosis and mass mortality in many aquatic animals. In aquatic environments, treatments cannot be limited to the diseased population alone, therefore treatment of the entire aquatic system is the only possible approach. Thus, the use of antibiotics to treat part of the infected animals requires a dose based on the entire biomass, which results in the treatment of uninfected animals as well as non-target normal microbial flora. A treatment method based on anti-virulence or quorum quenching has recently been proposed as an effective treatment strategy for aquatic animals. Polyhydroxy butyrates (PHB) are bacterial storage molecules, which accumulate in cells under nutritional stress. The degradation of PHB releases short-chain β-hydroxy butyric acid, which may act as anti-infective molecule. To date, there is very limited information on the potential anti-infective and anti-virulence mechanisms involving PHB. In this study, we aim to examine the effect of PHB on inhibition of the virulence cascade of Vibrio such as biofilm formation, luminescence, motility behaviour, haemolysin and quorum sensing. A luminescent Vibrio PUGSK8, tentatively identified as Vibrio campbellii PUGSK8 was tested in vitro for production of extracellular virulence factors and then established as a potential shrimp pathogen based on in vivo challenge experiments. The ability of Vibrio PUGSK8 to form biofilms and the effect of PHB on biofilm formation was tested in a 96-well microtitre-plate assay system. The motility behaviour of Vibrio PUGSK8 was evaluated using twitching, swimming and swarming plate assays. Reporter strains such as Chromobacterium violaceum CV026 and Agrobacterium tumefaciens were used to detect quorum-sensing molecules. Gas chromatography–mass spectrometry spectral analysis was performed to elucidate the fragmentation pattern and structure of N-hexanoyl homoserine lactone. PHB depolymerase activity in Vibrio PUGSK8 was quantified as the amount of the enzyme solution to hydrolyse 1 μg of PHB per min. An in vivo challenge experiment was performed using a gnotobiotic Artemia assay. Of the 27 isolates tested, the Vibrio PUGSK8 strain was selected for target-specific assays based on the high intensity of luminescence and production of virulence factors. The virulence cascade detected in Vibrio PUGSK8 include luminescence, motility behaviour, biofilm formation, quorum sensing and haemolysin production. Thus inhibition/degradation of the virulence cascade would be an effective approach to contain Vibrio infections in aquatic animals. In this report, we demonstrate that the degradation intermediate of PHB effectively inhibits biofilm formation, luminescence, motility behaviour, haemolysin production and the N-acyl-homoserine lactone (AHL)-mediated quorum-sensing pathway in PUGSK8. Interestingly, the growth of Vibrio PUGSK8 remains unaffected in the presence of PHB, with PHB degradation being detected in the media. PHB depolymerase activity in Vibrio PUGSK8 results in the release of degradation intermediates include a short-chain β-hydroxy butyric acid, which inhibits the virulence cascade in Vibrio PUGSK8. Thus, a molecule that targets quorum sensing and the virulence cascade and which is species/strain-specific could prove to be an effective alternative to antimicrobial agents to control the pathogenesis of Vibrio, and thereby help to contain Vibrio outbreaks in aquatic systems.

Identification and Initial Characterization of Prophages in Vibrio campbellii.

Phages are bacteria targeting viruses and represent the most abundant biological entities on earth. Marine environments are exceptionally rich in bacteriophages, harboring a total of 4x1030 viruses. Nevertheless, marine phages remain poorly characterized. Here we describe the identification of intact prophage sequences in the genome of the marine γ-proteobacterium Vibrio campbellii ATCC BAA-1116 (formerly known as V. harveyi ATCC BAA-1116), which presumably belong to the family of Myoviridae. One prophage was found on chromosome I and shows significant similarities to the previously identified phage ΦHAP-1. The second prophage region is located on chromosome II and is related to Vibrio phage kappa. Exposure of V. campbellii to mitomycin C induced the lytic cycle of two morphologically distinct phages and, as expected, extracellular DNA from induced cultures was found to be specifically enriched for the sequences previously identified as prophage regions. Heat stress (50°C, 30 min) was also found to induce phage release in V. campbellii. Notably, promoter activity of two representative phage genes indicated heterogeneous phage induction within the population.

Impact of Light, Temperature, Salinity and Glycerol on the Intensity of Luminescence and Growth of Marine Bioluminescent Bacteria Vibrio Campbellii (strain STF1)

Impact of Light, Temperature, Salinity and Glycerol on the Intensity of Luminescence and Growth of Marine Bioluminescent Bacteria Vibrio Campbellii (strain STF1)

Antibiotic resistance and plasmid profiling of Vibrio spp. in tropical waters of Peninsular Malaysia.

Vibrio species isolated from four different sampling stations in the west coast of Peninsular Malaysia were screened for their antimicrobial resistance and plasmid profiles. A total of 138 isolates belonging to 15 different species were identified. Vibrio campbellii, V. parahaemolyticus, V. harveyi, and V. tubiashii were found to predominance species at all stations. High incidence of erythromycin, ampicillin, and mecillinam resistance was observed among the Vibrio isolates. In contrast, resistance against aztreonam, cefepime, streptomycin, sulfamethoxazole, and sulfonamides was low. All the Vibrio isolates in this study were found to be susceptible to imipenem, norfloxacin, ofloxacin, chloramphenicol, trimethoprim/sulfamethoxazole, and oxytetracycline. Ninety-five percent of the Vibrio isolates were resistant to one or more different classes of antibiotic, and 20 different resistance antibiograms were identified. Thirty-two distinct plasmid profiles with molecular weight ranging from 2.2 to 24.8kb were detected among the resistance isolates. This study showed that multidrug-resistant Vibrio spp. were common in the aquatic environments of west coast of Peninsular Malaysia.

Association of Vibrio community with the Atlantic Mediterranean invasive alga Caulerpa cylindracea

In aquatic environments, vibrios are among the most abundant culturable microbes found either as free-living or associated with several marine organisms. The diseases due to some pathogenic vibrios are increasing worldwide thus the understanding of the mechanisms related to their spread is critically needed. In the present study, the abundance as well as the diversity of culturable vibrios associated to the surfaces of the green alga Caulerpa cylindracea (Sonder) were analyzed during different stages of algal development. The Vibrio densities ranged from 1.9 × 103 CFU mL− 1 to 2.2 × 104 CFU mL− 1. The Vibrio strains isolated from C. cylindracea surfaces were assigned to: Vibrio tubiashii, Vibrio neptunius, Vibrio rotiferianus, Vibrio communis, Vibrio owensii, Vibrio jasicida, Vibrio harveyi, Vibrio maritimus, Vibrio diabolicus, Vibrio campbellii, Vibrio pomeroyi, Vibrio crassostreae, and Vibrio aestivus. Although some of the species recovered can be pathogenic to benthic marine organisms, none is considered human pathogens. Only few of the isolated vibrios (V. campbellii, V. aestivus, V. pomeroyi and V. crassostreae) have a sporadic presence on the algal surfaces (i.e. they were found only during one sampling event) while most of the isolates were found in all the four sampling times. The association of these last Vibrio species and the surfaces of C. cylindracea needs to be elucidated in order also to ascertain whether vibrios might contribute to the successful spreading of the algal species.