EFFECT OF DISTANCE FROM THE POLLUTING FOCUS ON RELATIVE CONCENTRATIONS OF BACTEROIDES-FRAGILIS PHAGES AND COLIPHAGES IN MUSSELS

Concentrations of fecal bacteria, somatic and F-specific coliphages, a nd phages infecting Bacteroides fragilis in naturally occurring black mussels (Mytilus edulis) were determined. Mussels were collected over a 7-month period at four sampling sites with different levels Of fecal pollution. Concentrations of both fecal bacteria and bacteriophages i n mussel meat paralleled the concentration of fecal bacteria in the ov erlying waters. Mussels bioaccumulated efficiently, although with diff erent efficiencies, all of the microorganisms studied. Ratios comparin g the levels of microorganisms in mussels were determined. These ratio s changed in mussels collected at the different sites. They suggest th at bacteriophages infecting B. fragilis and somatic coliphages have th e lowest decay rates among the microorganisms studied, with the except ion of Clostridium perfringens. On the contrary, concentrations of F-s pecific coliphages showed a greater rate of decay than the other bacte riophages at sites more distant from the focus of contamination. Addit ionally, levels of enteroviruses were studied in a number of samples, and in these samples, the B. fragilis bacteriophages clearly outnumber ed the enteroviruses. The results of this study indicate that, under t he environmental conditions studied, the fate of phages infecting B. f ragilis released into the marine environment resembles that of human v iruses more than any other microorganism examined.