BIOLOGICAL INACTIVATION BY SINGLET OXYGEN - DISTINGUISHING O(2)(1-DELTA(G)) AND O(2)(1-SIGMA(G)+)

Experiments were performed to determine whether bacterial inactivation in the separated-surface-sensitizer system for singlet oxygen generation is due to O2(1DELTA(g)) or O2(1SIGMA(g)+)). The rates of inactivation of Gram-negative Salmonella typhimurium LT-2 and a nonpigmented strain of Gram-positive Sarcina lutea were found to increase linearly with the concentration of 1DELTA(g). The gas phase lifetime of the inactivating agent was found to be within the range of values expected for the gas phase lifetime of 1DELTA(g) rather than 1SIGMA(g)+. These measurements conclusively demonstrate that bacterial inactivation in this system is due predominantly to 1DELTA(g). Therefore, studies of bacterial inactivation with this singlet oxygen generating system can be used to assess the role of singlet oxygen in various biological and medically relevant situations.