The ATP level in the thermophilic cyanobacterium Synechococcus 6716 during light-dark transition and in the presence of some specific inhibitors

Abstract ATP concentrations in whole cells of Synechococcus 6716 are measured with the luciferin-luciferase method. Under aerobic conditions the ATP level in the dark is 70% of the level in the light; under anaerobic conditions this is 20%. The controversial time-dependent changes of the ATP content as reported in earlier studies are discussed in relation to the used ATP determinations. The electron transfer inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and Antimycin A have no effect on the ATP level neither in the light, nor in the dark. KCN only affects the ATP level in the dark under aerobic conditions. The energy transfer inhibitors N , N '-dicyclohexylcarbodiimide (DCCD) and Venturicidin are effective both in the light and in the dark, be it for about 50%.