What is the primary reason for bacterial death in the death phase?
Transition to death phase reflects inability to maintain energy homeostasis and repair. Prolonged incubation exhausts fermentable carbon, electron acceptors, phosphate, amino acids, halting ATP generation via respiration and substrate level phosphorylation. Concomitantly toxic end products accumulate: organic acids acetate and lactate lower pH below 5, alcohols ethanol, ammonia, hydrogen sulfide inhibit cytochrome oxidases, and reactive oxygen species superoxide and H2O2 from autooxidation damage iron sulfur clusters. Oxidative lesions cause DNA strand breaks, protein carbonylation, membrane l
Ref: Brock Biology of Microorganisms, 16th ed., Chapter 6: Death phase - Toxic metabolites accumulation.