The Infection of Freshwater Cyanobacteria by Their Phages

Abstract

Phage lysis of cyanobacteria could significantly influence nutrient availability in aquatic systems. We examined the requirements of phage infection in freshwater cyanobacteria and identified several factors that affected infectivity. Light was found to be required for the infection of a wild cyanobacterial isolate (GH6) by bacteriophage AS-1. An identical requirement was found for the infection of Nostoc by its phage An-29. In both the wild isolate and Nostoc, the absence of light during infection reduces the yield of progeny phages to the background over the course of two rounds of infection. In addition, filtering out different portions of the visible light spectrum results in reduced progeny yield. The culture density was also found to strongly influence the ability of AS-1 to infect S. elongatus and the wild isolate. Phage progeny production and the timing of progeny release were influenced by culture density.