Hydrogen Sulphide Production by Non-multiplying Organisms and its Inhibition by Antibiotics

Hydrogen sulphide production by washed bacterial suspensions in buffered substrate solutions was examined. The suspensions were tested for H2S production from cysteine, cystine, homocystine, methionine, mercaptoacetate, sulphite, sulphate or thiosulphate. Some strains of the Proteus, Klebsiella, Salmonella, Arizona and Bethesda groups produced hydrogen sulphide when 1011 or more washed organisms/ml. were incubated at 37° without an added source of sulphur. Generally tenfold greater quantities of bacteria were required to produce hydrogen sulphide within 24 hr. from homocystine, sulphite or thiosulphite as compared with cystine or cysteine. For the production of hydrogen sulphide from sodium mercaptoacetate, 10- and 100-fold larger quantities of bacteria were required. In the Brucella group all strains behaved alike, except two non-smooth strains which were spontaneously agglutinated in the buffer + substrate solutions and did not produce hydrogen sulphide. Among the Enterobacteriaceae the most active strains belonged to the Proteus group, the most inactive strains to the Large-Sachs group. All strains of the Arizona and Bethesda groups, and some Klebsiella, Salmonella, Serratia and Providence strains multiplied on cysteine and cystine + buffer solutions, utilizing for growth the split products, pyruvic acid and ammonia.

Hydrogen sulphide production was inhibited by penicillin or streptomycin. Non-multiplying micro-organisms exposed to penicillin, streptomycin, aureomycin or chloramphenicol for 24 hr. at 37° remained viable, but lost their ability to produce hydrogen sulphide. This ability was regained on subculture. The hydrogen sulphide production of bacteria inactivated by penicillin was restored when the cells were removed by centrifugation, and residual penicillin destroyed by penicillinase. Addition of bacterial extracts heated at 50° or pyridoxal phosphate, separately or together to inactivated bacteria, reactivated the hydrogen sulphide production of Proteus vulgaris. Bacterial extracts heated at 100° exerted slight reactivating effects.