Identification of Vibrio parahemolyticus isolated from cultured Eriocheir sinensis and pathogenicity of its extracellular products

Three strains of bacteria were isolated from the diseased Eriocheir sinensis , which were cultured in the ponds in Hangzhou. Morphological, physiological and biochemical characteristics of these isolates were the same as those of Vibrio parahenwlyticus, therefore, these pathogens isolated from the diseased E. sinensis were identified as Vibrio parahenwlyticus. The mortality of artificial infection was 100% , which ascertained that the bacterial isolates were the pathogens of the E. sinensis. The pathogens were highly sensitive to streptomycin, rifampin, kanamycin, SMZ + TMP, ciprofloxacin, norfloxacin, tetracycline, chloramphenicol, ofloxacin, ceftazidime, ceftriaxone, nalidixic acid. The suspension was centrifuged, precipitated by (NH4)SO4, dialysed, concentrated and filter sterilized, and the extracellular products obtained were found to show gelatinase, chitinase, amylase, caseinase, lipase, phospholipase activities, and to be highly toxic to E. sinensis .