Mutant of Rhodopseudomonas spheroides Unable to Grow Aerobically

We isolated a mutant of Rhodopseudomonas spheroides that grows normally under photosynthetic conditions but is unable to grow exponentially under aerobic conditions. Photosynthetically grown cultures of the mutant increase in mass and cell number for about 10 hr after transfer to aerobic conditions. During this time, no heme pigments are synthesized and the Q(O(2)) declines. In the mutant, synthesis of heme pigments is obligatorily coupled to synthesis of bacteriochlorophyll.