RESUMEN
Using Vibrio fluvialis Ⅱ as host bacteria, 19 bacteriophages have been isolated from the 76 samples which were collected from Haliotis discus hannai ～growing seawater in Dalian marine culture company Dalian, liaoning province from May in 1996 to August I 1997. Ultrastructure of 19 bacteriophages were observed with electron to Bradley the results showed that of these bacteriophages belonged to Bradley A type, they have hexagonal heads of bacteriophages were identified with VP1,VP2,VP4,VP8 as representatives respectively. The phages remain stable at pH6. 0～10. 0, moreover VP2,VP4 and VP8 are rather stable at basic pHs. Although the characterization of heat inactivation course of VP4 is different from others, four phages are sensitive to heat and inactivated at 80℃ in 5 minutes. One step growth experiment showed that the eclipse period of VP1,VP2,VP4,VP8 are sensitive to heat and the eclipse period of VP1, VP2, VP4, VP8 are 42, 30, 46, 28 minutes. In this experiment we have isolated at least four different types phages, it suggest that in fact there is a population of phages in the seawater environment. The result of this study provided a way to find the potential value of phages as an indicator of pathogenic microorganisms Vibrio fluvilis Ⅱ in marine environment.