Marine bacteriophage reproduction under nutrient-limited growth of host bacteria. I. Investigations with six phage-host systems

Abstract

Bacteriophage reproduction was investigated with 6 phage-host systems (PHS) isolated from the North Sea near Helgoland, Germany, with the hosts adapted to growth at 6 or 0.6 mg organic nutrients l-1. For 5 of the PHS, similarities in production were observed to depend upon the time of infection during a transition period which included the last hours of the logarithmic growth phase and the first 1 to 2 d of the stationary growth phase of the host bacteria. Over this period the extent and/or the rate of phage production d-1 decreased greatly. After longer incubation before addition of phage, the relative ability of host cells to propagate phage either ceased (3 PHS) or was regained (1 PHS) or remained the same as during the transition period in regard to final phage concentrations (1 PHS). The remaining PHS showed no phage reproduction at the low nutrient concentration. With phage- resistant mutant bacteria serving as competitors for nutrients, phage production was drastically reduced. The present findings are in agreement with observations concerning concentrations of infective virions in fresh seawater samples. They failed, however, to provide evidence for the hypothesis that release of mature phage in starving marine bacteria is delayed until sufficient nutrients become available.