INTERACTION OF <i>PLECTONEMA BORYANUM</i> (CYANOPHYCEAE) AND THE LPP‐CYANOPHAGES IN CONTINUOUS CULTURE¹

Abstract

SUMMARY Continuous culture techniques are used to study long‐term population interactions between Plectonema boryanum Gomont, a filamentous bluegreen alga, and the LPP‐viruses which infect it. After LPP‐I (virulent cyanophage) infection of sensitive algae, 3 oscillations occur in cell density with concomitant oscillations in virus titer before final stabilization of both algal and viral concentrations. After LPP‐ID and LPP‐2 (temperate viruses) infection, oscillation in cell density occurred with burst of virus particles. Resistant algae always repopulated the chemostat; lysogeny was not established. The interaction between Plectonema that was resistant to virus infection and the 3 LPP‐cyanophages resulted in rapid elimination of the viruses from the chemostat in the effluent. When lysogenic P. boryanum was tested, a law population of virus was present in the chemostat throughout the incubation period indicative of spontancous induction. Clones of lysogenic algae were isolated.