COMPARISONS OF VIRULENCE OF VIBRIONS ISOLATED FROM BOTH DISEASED AND HEALTHY POSTLARVAE OF ABALONE

Since 2002,massive death of abalone postlarvae has swept across the south coast of China.To explore the cause behind it,an investigation has been carried out to compare the abilities of vibrios to produce extracellular virulent factors from different settings.In this study,16 and 34 vibrios were isolated from both diseased and healthy postlarvae of abalone in 2004,respectively.Comparisons of their extracellular virulent factor producing abilities revealed that 20.59%of vibrios from the healthy postlarvae did not produce four extracellular enzymes but could lyse goat blood agar,64.71% produced enzymes or hemolysis.The rest possessed weak abilities to produce four enzymes and/or hemolysis.Contrarily,100% vibrios from diseased postlarvae produced extracellular enzymes or hemolysis.Among them,25% produced four enzymes and hemolysis,68.75% produced either extracellular enzymes or haemolysis on goat blood agar.In conclusion,vibrios from diseased postlarvae showed better abilities to produce extracellular protease,gelatinase,phospholipase and lipase as well as hemolysis than those from the healthy postlarvae.Furthermore,strains x99-2 and x100-8 were considered to be potential pathogens on the basis of their abilities to produce extracellular virulent factors and warrant further studies.