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SUMMARY: The utilization of several inorganic and organic sulphur compounds by three strains of Clostridium perfringens and the production of hydrogen sulphide from these compounds was investigated. Sulphate, sulphite, thiosulphate and sulphide cannot supply sulphur to the organism, neither do they have any effect, when added in non-toxic concentrations, on the growth in media containing utilizable organic sulphur. Cystine or cysteine, which can be replaced by glutathione, were required by the three strains tested; no additional sulphur source was needed by two of the strains, the third requiring also methionine, which can be replaced by homocyst( e)ine. Hydrogen sulphide is produced by growing cultures from sulphite, thiosulphate, cystine, cysteine and glutathione, but not from methionine. Different enzyme systems are concerned with hydrogen sulphide production from cystine and sulphite, respectively. The sulphite-reducing capacity of some cultures was often decreased after several passages in laboratory media, the presence of nicotinamide being then required for this reduction. Sulphite was reduced to sulphide by sus- pensions of resting organisms. The presence of a liydrogenase system is suggested by preliminary experiments, the organisms being able to activate molecular hydrogen for reduction of methylene blue and sulphite. Other hydrogen donors are utilized by the organisms, in particular glucose. The addition of sulphites does not induce growth on substrates which do not support growth in sulphite-free media. Hydrogen sulphide is produced by micro-organisms from compounds contain- ing organic sulphur and from inorganic sulphur compounds, e.g. thiosulphate, sulphite, sulphate. Many different bacteria produce hydrogen sulphide from peptones, cystine and cysteine (Clarke, 1953; Stekol & Ransmeier, 1942), and some from thiourea (Tanner, 1917), but not from taurine (Sasaki & Otsuka, 1912; Burger, 1914). A few produce H,S from thiosulphate (Tanner, 1917; Tilley, 1923a, b) and -? rom sulphite (Tilley, 1923a, b; Wilson, 1922-3; Tanner, 1917). Only a small group of sulphate-reducing bacteria (vibrios) has so far been described, first by Beijerinck (1895) and later studied more closely by several investigators. Clostridium perfringens is capable of reducing sulphite in suitable media and forms colonies black with precipitated ferrous sulphide in iron sulphite agar (Wilson & Blair, 1924,1927). The occurrence of C. perfringens in sewage before and after treatment in purification plants is used at this Institute as an indica- tion of the effectiveness of purification, together with the coliform count. The isolation and counting is based on the sulphite-reducing capacity of these bacteria (Ronde & Hvid-Hansen, 1953). The mechanism of sulphite reduction, as well as that of sulphate and thiosulphate reduction, is still obscure, and it is also unknown what, if any, the significance of this reaction is to the bacterial metabolism. The aim of the present work is to investigate the conditions governing the reduction of sulphite by C. perfringrens.

The Availability of Sulphur for Clostridium perfringens and an Examination of Hydrogen Sulphide Production