Nitrate, Nitrite and Indole Reactions of Gas Gangrene Anaerobes

In an attempt to work out a scheme for the rapid identification of the gas gangrene organisms (Reed and Orr, 1941), many of the published reports of nitrate reduction and indole formation by this group of organisms were found to be contradictory. The nature of the contradictions suggested that this was largely the result of faulty interpretation of results so clearly described for the nitrate reduction of bacteria in general by Conn (1936). NITRATE REDUCTION Woods (1938) found that washed suspensions of Clostridium welchii catalyzed the reduction of NOs, NO2 and NH20H to NH3 by molecular hydrogen. More-over, during the reduction of NO3 to NH3 he demonstrated the appearance and disappearance of NO2. This made it probable that tests for NO2 alone in grow-ing cultures of this and related species would give little indication of the nitrate-reducing action of the organisms. A somewhat more detailed examination has therefore been made. Cultures were tested for nitrite production in the following medium, Reed and Orr (1941): Bacto tryptone..................................................... 20 grams Na2HPO4...................................................... 2 grams