Fig. 1. Schematic illustration of antibacterial photodynamic therapy (left). Photodynamic effects explained on the molecular level (right). Upon absorbing a photon, a photosensitizer molecule (S₀) enters a short-lived excited singlet state (¹S*), moving then to a triplet state (³S*). After that, two scenarios are possible: either ³S* reacts with the substrate and intermittent radicals are produced that damage cell structures and macromolecules inside the cell (type I), or energy from ³S* is transferred to oxygen, and reactive singlet oxygen ¹О₂ is produced that also damages cell structures or its macromolecules

Fig. 2. Possible scenarios of phage infection in the bacterial population. Reversible stages are shown in red (mutations, premature sequence termination in prophages, deletions, insertions, etc.)

Fig. 3. Schematic of bacterial cell envelopes and phage lysin classes that degrade the peptidoglycan layer