Bruno Gomez-Gil

The use and selection of probiotic bacteria for use in the culture of larval aquatic organisms

Research in probiotics for aquaculture is at an early stage of development and much work is still needed. The principal bacterial groups tested as probionts in the culture of shrimp, crab, oyster and fish have been Vibrio, Pseudomonas, Bacillus, and several lactobacilli. The available information is inconclusive, since few experiments with sufficiently robust design have been conducted to permit critical evaluation. Experiments have mainly been conducted with fish larvae, where significant reductions in mortality have been obtained. Most of the work reviewed in this article describes commercial hatchery experiments rather than rigorous laboratory investigations and the focus is principally shrimp larviculture.

Species of Vibrio isolated from hepatopancreas, haemolymph and digestive tract of a population of healthy juvenile Penaeus vannamei

Abstract The number and species of Vibrio spp. bacteria that may be present in normal healthy Penaeus vannamei juveniles are described. The hepatopancreas, stomach, intestine and haemolymph of P. vannamei juveniles were sampled. All three areas of the digestive tract contained a diverse population of Vibrio spp. but the haemolymph contained bacteria in only 14.3% of the animals sampled, with counts of Vibrio spp. ranging from 2×10 2 to 3×10 3 CFU/ml. The Vibrio spp. isolated from the digestive tract included both sucrose and non-sucrose fermentors whereas the haemolymph contained only non-sucrose fermentors. The findings of this study would suggest that there may be a wide range of Vibrio spp. in the hepatopancreas of normal healthy P. vannamei .

The Vibrio core group induces yellow band disease in Caribbean and Indo-Pacific reef-building corals

Aims:  To determine the relationship between yellow band disease (YBD)‐associated pathogenic bacteria found in both Caribbean and Indo‐Pacific reefs, and the virulence of these pathogens. YBD is one of the most significant coral diseases of the tropics.

Phenotypic diversity amongst Vibrio isolates from marine aquaculture systems

A total number of 1473 Vibrio isolates were collected from different aquaculture systems in many countries. Isolates were obtained from bivalves (mussels, scallops, oysters), shrimp and fish, sea urchins, live feed (algae, Artemia, rotifers), seaweed, aquaculture market products and from the aquaculture environment (tank water, seawater, sediments). Eggs, healthy and diseased or dead larvae, and adult organisms were sampled from cold-water species and moderate- to warm-water species. All isolates were phenotypically characterized using the Biolog GN technique. Eighty-nine different clusters were obtained, of these clusters, only 33 were identified comprehending 992 isolates. The remaining 56 groups did not cluster with any of the included type strains and remained unidentified. Seventy-eight isolates did not cluster with any other strain. It was shown that the Vibrio genus is a phenotypically diverse group making the identification with the Biolog system difficult and unreliable.

Multilocus Sequence Analysis Reveals that Vibrio harveyi and V. campbellii Are Distinct Species

ABSTRACT Identification and classification of Vibrio species have relied upon band pattern methods (e.g., amplified fragment length polymorphism) and DNA-DNA hybridization. However, data generated by these methods cannot be used to build an online electronic taxonomy. In order to overcome these limitations, we developed the first standard multilocus sequence scheme focused on the ubiquitous and pathogenic Vibrio harveyi species group (i.e., V. harveyi, V. campbellii, V. rotiferianus, and a new as yet unnamed species). We examined a collection of 104 isolates from different geographical regions and hosts using segments of seven housekeeping genes. These two species formed separated clusters on the basis of topA, pyrH, ftsZ, and mreB gene sequences. The phylogenetic picture obtained by the other three loci, i.e., gyrB, recA, and gapA, was more complex though. V. campbellii appeared nested within V. harveyi in the recA trees, whereas V. harveyi formed a tight nested cluster within V. campbellii by gapA. The gyrB gene had no taxonomic resolution and grouped the two species together. The fuzziness observed in these three genes seems not be related to recombination but to low divergence due to the accumulation of only a few substitutions. In spite of this, the concatenated sequences provided evidence that the two species form two separated clusters. These clusters did not arise by recombination but by accumulation of point mutations. V. harveyi and V. campbellii isolates can be readily identified through the open database resource developed in this study (http://www.taxvibrio.lncc.br/ ). We argue that the species should be defined by evolutionary criteria. Strains of the same species will share at least 95% concatenated sequence similarity using the seven loci, and, most importantly, cospecific strains will form cohesive readily recognizable phylogenetic clades.

In vitro susceptibility to 15 antibiotics of vibrios isolated from penaeid shrimps in Northwestern Mexico.

The sensitivity of 144 isolates of Vibrio spp isolated from shrimp was compared using common antibiotics and those used in the shrimp industry. The in vitro susceptibility of the isolates was studied using amikacin, ampicillin, carbenicillin, cephalothin, cefotaxime, ceftriaxone, chloramphenicol, gentamicin, netilmicin, nitrofurantoin, pefloxacin, trimethoprim-sulphamethoxazole, enrofloxacin, oxytetracycline and florfenicol. The relationship between the minimum inhibitory concentration and the disk inhibition zone was also studied for some antibiotics.

Field and experimental evidence of Vibrio parahaemolyticus as the causative agent of acute hepatopancreatic necrosis disease of cultured shrimp (Litopenaeus vannamei) in Northwestern Mexico.

ABSTRACT Moribund shrimp affected by acute hepatopancreatic necrosis disease (AHPND) from farms in northwestern Mexico were sampled for bacteriological and histological analysis. Bacterial isolates were molecularly identified as Vibrio parahaemolyticus by the presence of the tlh gene. The tdh-negative, trh-negative, and tlh-positive V. parahaemolyticus strains were further characterized by repetitive extragenic palindromic element-PCR (rep-PCR), and primers AP1, AP2, AP3, and AP and an ems2 IQ2000 detection kit (GeneReach, Taiwan) were used in the diagnostic tests for AHPND. The V. parahaemolyticus strains were used in immersion challenges with shrimp, and farmed and challenged shrimp presented the same clinical and pathological symptoms: lethargy, empty gut, pale and aqueous hepatopancreas, and expanded chromatophores. Using histological analysis and bacterial density count, three stages of AHNPD (initial, acute, and terminal) were identified in the affected shrimp. The pathognomonic lesions indicating severe desquamation of tubular epithelial cells of the hepatopancreas were observed in both challenged and pond-infected shrimp. The results showed that different V. parahaemolyticus strains have different virulences; some of the less virulent strains do not induce 100% mortality, and mortality rates also rise more slowly than they do for the more virulent strains. The virulence of V. parahaemolyticus strains was dose dependent, where the threshold infective density was 104 CFU ml−1; below that density, no mortality was observed. The AP3 primer set had the best sensitivity and specificity. Field and experimental results showed that the V. parahaemolyticus strain that causes AHPND acts as a primary pathogen for shrimp in Mexico compared with the V. parahaemolyticus strains reported to date.

Enterovibrio norvegicus gen. nov., sp. nov., isolated from the gut of turbot (Scophthalmus maximus) larvae: a new member of the family Vibrionaceae

Twenty-two isolates originating from the gut of healthy cultured turbot larvae in Norway were investigated using a polyphasic approach. Amplified fragment length polymorphism fingerprinting analysis showed that the isolates have typical patterns and form two main groups. Phylogenetic analysis revealed that the isolates belong to the gamma-Proteobacteria, with Vibrio hollisae as their closest neighbour. DNA-DNA hybridization, chemotaxonomic and phenotypic analyses further proved that these isolates represent a tight novel taxon that differs from currently described species in the family Vibrionaceae. It is proposed that these novel isolates be accommodated in a new genus, Enterovibrio gen. nov., with Enterovibrio norvegicus sp. nov. as the type species. Isolates were motile by a polar flagellum, positive for oxidase, catalase, arginine dihydrolase and beta-galactosidase, but negative for the Voges-Proskauer reaction. They produced indole, did not reduce nitrate and were resistant to the vibriostatic agent O/129. The DNA G+C content of E. norvegicus was 47.1-47.9 mol%. The type strain is E. norvegicus LMG 19839(T) (= CAIM 430(T)).

Draft Genome Sequence of Vibrio parahaemolyticus Strain M0605, Which Causes Severe Mortalities of Shrimps in Mexico

ABSTRACT Acute hepatopancreatic necrosis disease (AHPND), also known as early mortality syndrome (EMS), causes high mortalities in cultured shrimps in Asia (L. Tran et al., Dis. Aquat. Organ. 105:45–55, 2013, http://dx.doi.org/10.3354/dao02621). Here, we report the draft genome sequence of one Mexican strain of Vibrio parahaemolyticus that causes similar clinical signs in diseased shrimps.

Genomic diversity of vibrios associated with the Brazilian coral Mussismilia hispida and its sympatric zoanthids (Palythoa caribaeorum, Palythoa variabilis and Zoanthus solanderi)

Aims:  A taxonomic survey of the vibrios associated with the Brazilian endemic coral Mussismilia hispida and the sympatric zoanthids (i.e. Palythoa caribaeorum, Palythoa variabilis and Zoanthus solanderi).