Vibrios associated with Litopenaeus vannamei larvae, postlarvae, broodstock, and hatchery probionts

Several bacteriological surveys were performed from 1994 to 1996 at differe nt Litopenaeus vannamei hatcheries (in Ecuador) and shrimp farms (in Mexico ). Samples were taken from routine productions of healthy and diseased L. v annamei larvae, postlarvae, and their culture environment and from healthy and diseased juveniles and broodstock In Ecuador, the dominant bacterial fl ora associated with shrimp larvae showing symptoms of zoea 2 syndrome, mysi s mold syndrome, and bolitas syndrome has been determined. Strains were cha racterized by Biolog metabolic fingerprinting and identified by comparison to a database of 850 Vibrio type and reference strains. A selection of:stra ins was further genotypically fine typed by AFLP. Vibrio alginolyticus is p redominantly present in all larval stages and is associated with healthy na uplius and zoea stages. AFLP genetic fingerprinting shows high genetic hete rogeneity among V. alginolyticus strains, and the results suggest that puta tive probiotic and pathogenic strains each have specific genotypes. V. algi nolyticus was found to be associated with larvae with the zoea 2 syndrome a nd the mysis mold syndrome, while. different Vibrio species (V. alginolytic us and V. harveyi) are associated with the bolitas syndrome. V. harveyi is associated with diseased postlarvae, juveniles, and broodstock. The identit ies of the strains identified as V. harveyi by the Biolog system could not be unambiguously confirmed by AFLP genomic. fingerprinting. Vibrio strain S TD3-988 and one unidentified strain (STD3-959) are suspected pathogens of o nly juvenile and adult stages. V. parahaemolyticus, Photobacterium damselae , and V. mimicus are associated with juvenile and adult stages.