Photodynamic response in bacteria.

The photodynamic lethal response of Gram negative bacteria was found to be a one event phenomenon as previously reported. However, the kinetics of the lethal response in Gram-positive microorganisms was found to be more complex. The survivor response of the latter was dividable into at least two distinct parts, each of which could be influenced by various environmental and genetic factors. Some correlation was found between sensitivity or resistance to x-ray and ultraviolet radiations and sensitivity or resistance to photodynamic action.