PHAGES INFECTING VIBRIO-VULNIFICUS ARE ABUNDANT AND DIVERSE IN OYSTERS (CRASSOSTREA-VIRGINICA) COLLECTED FROM THE GULF-OF-MEXICO

Phages infecting Vibrio vulnificus were abundant (> 10(4) phages g of oyster tissue(-1)) throughout the year in oysters (Crassostrea virgini ca) collected from estuaries adjacent to the Gulf of Mexico (Apalachio cola Bay, Fla.; Mobile Bay, Ala.; and Black Bay, La.). Estimates of ab undance ranged from 10(1) to 10(5) phages g of oyster tissue(-1) and w ere dependent on the bacterial strain used to assay the sample, V., vu lnificus was near or below detection limits (< 0.3 cell g(-1)) from Ja nuary through March and was most abundant (10(3) to 10(4) cells g(-1)) during the summer and fall when phage abundances also tended to be gr eatest, The phages isolated were specific to strains of V. vulnificus, except for one isolate that caused lysis in a few; strains of V., par ahaemolyticus. Based on morphological evidence obtained by transmissio n electron microscopy, the isolates belonged to the Podoviridae, Stylo viridae, and Myoviridae, three families of double-stranded DNA phages, One newly described morphotype belonging to the Podoviridae appears t o be ubiquitous in Gulf Coast oysters, Isolates of this morphotype hav e an elongated capsid (mean, 258 nm; standard deviation, 4 nm; n = 35) , with some isolates having a relatively broad host range among strain s of V. vulnificus. Results from this study indicate that a morphologi cally diverse group of phages which infect V. vulnificus is abundant a nd widely distributed in oysters from estuaries bordering the northeas tern Gulf of Mexico.