Studies of the metabolism of the strict anaerobes (genus: Clostridium)

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Abstract
Many amino acids and other biologically interesting compounds were investigated as to their ability to act as H donators with washed suspensions of Cl. sporogenes. Many of these compounds could be dehydrogenated, although usually certain amino acids were better H donators. A study was made of the conditions which may influence the results: age of the culture; pH of the medium; composition of the medium; and pH at which the dehydrogenations were performed. Usually the activity towards different substrates decreases during continued incubation. Some substrates, e.g., ethyl alcohol, are more rapidly dehydrogenated by older cultures when cultivated on neopeptone. The pH curves for different substrates are completely different and the pH optima for dehydrogenation may vary greatly. Cultivated on neopeptone at pH 7.4 the pH-optimum for d-alanine was 9.3, for ethyl alcohol 8.5, for acetaldehyde 6.7, and for pyruvic acid 6. Comparison of dehydrogenating potencies must be made with due regard to the pH at which they have been investigated. Marked changes in the pH curves for the different substrates were observed when the bacteria employed were cultivated at a more acid reaction than pH 7.4; in general these curves showed a shifting towards the acid side, indicating an adaptation of the organism so that these substrates could be attacked more easily at low pH. Addition of glucose to the culture medium increased the ability of the organism to use glucose as a H donator, and also, more markedly, that of ethyl alcohol. The different behaviors of the dehydrogenases acting on d-alanine, pyruvic acid or ethyl alcohol towards poisons such as HCN, As2O3, NaF, CuSO4, are descr.