Bacteria have no specified life-span; they suffer no "programmed" death. When environmental factors are right, bacteria are immortal. These tiny organisms can be killed, of course, by predators, through starvation, and by encounters with kitchen-counter sprays, chlorinated water and terrorist-like antibiotics.
The light-eating cyanobacteria start an oxygen revolution. Due to their waste, the concentration of oxygen in the atmosphere jumps from virtually nothing to one part in five. For those masses of fermenters with no protective hideaway, an oxygen catastrophe results. A guess is that up to 90 percent of anaerobes die in the revolution.