Anaerobic and aerobic growth of purple bacteria (Athiorhodaceae

SUMMARY: Studies on the anaerobic growth of aerobically adapted purple bacteria show that the same growth factors sufFice for both aerobic and anaerobic growth, thus supporting van Niel’s formulations of photosynthesis and carbon assimilation in these forms, and his thesis that the previously observed need for peptone or yeast extract could be attributed to their content of essential growth factors. Combinations of glutamate and succinate (or fumarate) were especially good promoters of growth in malate media; it is possible that their effectiveness was referable to their allowing a by-pass of the CO, requirement. The production of molecular hydrogen by purple bacteria is discussed in relation to the reducing intensities attained in cultures. A bottle technique for anaerobic cultures, and a flask technique for aerobic cultures, are described in detail. Photosynthesis in purple bacteria is best observed when they are grown anaerobically (van Niel, 1944, 1949). It was therefore important to determine whether the growth factors, aneurin, nicotinic acid, biotin and p-aminobenzoic acid, needed for aerobic growth (Hutner, 1946), would suffice for anaerobi