SUMMARY: A mutant of Pseudomonas aeruginosa affected in aerobic growth (aer) was partially characterized. When shifted from anaerobic to aerobic conditions mutant bacteria continued growth. During this aerobic growth after the shift the mutant bacteria differed from the wild type in some respects. First, the concentration of intracellular haem decreased gradually, whereas coproporphyrin was released into the culture fluid. Apparently haem synthesis is blocked under aerobic conditions, so oxygen uptake by the mutant culture did not increase as much as by the wild type after a shift. Second, the anaerobic nitrate-respiratory system of the mutant exhibited an altered sensitivity to oxygen after a shift to aerobiosis. Nitrate and nitrite reduction were not inhibited and nitrite reductase synthesis was not repressed by oxygen. P/O values determined in intact bacteria showed that respiration with oxygen was still coupled to ATP formation in the mutant.
SUMMARY: The fission yeast Schizosaccharomyces pombe was grown in the presence of 10-3 to 10-6 M-sodium tellurite. Growth was inhibited by tellurite and at concentrations above 10-5 M a black reduction product (probably tellurium) was visible in sedimented cells. Electron microscopy of thin sections showed the reduction product to be on a localized system of membranous vesicles forming an area about 500 nm in diameter. Membrane systems of this type were not seen in control cells but they possibly resulted from the degeneration of some of the mitochondria.