Biological inactivation by single oxygen: distinguishing O 2( 1Δg) and O 2( 1Σg+)

Abstract

Experiments were performed to determine whether bacterial inactivation in the separated-surface-sensitizer system for singlet oxygen generation is due to O 2( 1 Δ g) or O 2( 1 Σ g +). The rates of inactivation of Gram-negative Salmonella typhimurium LT-2 and a nonpigmented strain of Gram-positive Sarcina lutea were found linearly with the concentration of 1 Δ 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 1 Δ g rather than 1 Σ g +. These measurements conclusively demonstrate that bacterial inactivation in this system is due predominantly to 1 Δ 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.