An energy-transducing pathway in halobacteria is described. Arginine mediates substrate level phosphorylation and allows the cells to grow anaerobically. Bacteriorhodopsin plus light can function as an alternative energy source under these conditions, provided the cells contain the pigment when transferred to the anaerobic environment. Therefore the selection of mutants functionally defective in ATP synthase or bacteriorhodopsin becomes possible.
Hartmann et al. (Tue,) studied this question.