NATIVE MARINE BACTERIOPHAGES

Isolation and cultivation of marine bacteriophages have shown that the y are ubiquitous in seawater, and direct counting has shown that the t otal numbers of viruses frequently exceed the bacterial concentration by a factor of 10. About 150 different isolates of phages from marine environments have been characterized in the literature reviewed in the present report. Knoblike projections on phage heads seem to be a morp hological property more common in marine phages than among phages from other sources. The cultured phages were generally much larger than th e majority of viruses observed by direct transmission electron microsc opy of seawater samples, indicating that culturing methods are not pro viding unbiased samples of environmental viruses. Cultured marine viru ses frequently are more sensitive to organic solvents than the more in tensively studied phages from other sources. Burst sizes from recent i n situ studies are 50% lower than the average from culture studies. Ph ages in the marine environment may have half lives lasting less than a day, with consequent high turnover. Host ranges varies, and cross spe cies host ranges have not been demonstrated. More information and furt her development of methods are needed, both from culture and from in s itu studies.