- Volume 130, Issue 1, 1984

The influence of Na+ and K+ on the synthesis and secretion of extracellular glucosyltransferase (GTF; EC 2.4.1.5) and fructosyltransferase (FTF; EC 2.4.1.10) by Streptococcus sanguis NCTC 7865 and Streptococcus sanguis Challis NCTC 7868 has been determined. No FTF and little or no mutansucrase (GTF-I) activities were detectable during growth on glucose or sucrose unless the Na+/K+ ratio of the cultures was kept low. Increasing K+ concentrations stimulated the production of FTF and dextransucrase (GTF-S), but all glycosyltransferase activities decreased in high K+ media when the growth pH was maintained with NaOH instead of KOH, indicating that the Na+/K+ ratio effect was due principally to Na+ inhibition. Significant GTF and FTF activities were detected in a putative GTF− mutant of strain Challis grown in high K+ medium but not in high Na+ medium, suggesting that the mutant might be defective in a regulatory gene.

Inhibition by sodium azide of the growth of Bacillus coagulans decreased but the cytochrome content, particularly cytochrome d, increased with increasing growth temperature. Higher cytochrome d content correlated with increased cyanide resistance of NADH oxidase, but azide resistant activity was found in mesophilic and thermophilic cultures. Anaerobic growth at 37 °C was totally inhibited by 1 mm-azide. At 55 °C; growth occurred with 4 mm-azide, but the cell yield was reduced by 60%. ATPase activity was sensitive to azide but inhibition varied with both growth and assay temperatures. ATPase from cells grown at 55 °C; was least sensitive when assayed at 55 °C;. Possible changes in ATPase which could account for the temperature-dependent azide sensitivity are discussed.

The anaerobic fermentation of glucose by Bacillus macerans ATCC 7068 was studied in batch culture with and without pH control. The fermentation was characterized by two distinct metabolic phases. In the primary growth phase, the concentrations of ethanol and acetic acid increased exponentially, and formate was detected as a minor product. The secondary phase was marked by a slowing and eventual cessation of growth, along with the disappearance of formate and acetate, and the appearance of H2, CO2, and acetone. Exogenously-added substrates were converted with stoichiometries of 1 formate → 1 H2 + 1 CO2, and approximately 2 acetate → 1 acetone. Consumption of > 8 g glucose 1−1 required exogenous pH control, and acetone formation was strongly pH-dependent. Glucose was fermented by the Embden-Meyerhof pathway. Cell extracts contained pyruvate formate-lyase and formate dehydrogenase activities, but only low pyruvate dehydrogenase activity. A balanced fermentation pathway is presented which is consistent with reaction stoichiometries and [14C]glucose labelling data in whole cultures, and with enzyme activities in extracts. The pathway is compared with those of other facultative anaerobes and the acetone-producing Clostridium acetobutylicum.

Catalase activity in liver homogenates was studied in normal and low endotoxin (LPS) responder mice treated with various doses of LPS from S. typhimurium B or bearing tumours induced by 3-methylcholanthrene. In normal LPS-responder (C3H/f) mice a dose of 40 μg LPS or tumour induction caused a reduction of catalase activity of about 50%. In low responder (C3H/HeJ) mice a reduction of the enzyme activity of over 40% was observed at a dose of 200 μg LPS. Tumour induction had no effect. In tumour-bearing mice of both strains the presence of a tumour seemed to interfere with the ability of LPS to depress hepatic catalase activity. Since a reduction of the enzyme activity in response to LPS or tumour induction seemed to be influenced by the LPS responsiveness of the mice, this study suggests that there could be common mediators of this effect. It is also possible that tumour induction might influence host responses to LPS.