Effect of KCN on the motility of Treponema pallidium.

Virulent Treponema pallidum has been shown to survive in KCN-containing artificial medium. Oxygen uptake being sensitive to cyanide, the observation indicates that treponemes do not have a cytochrome oxidase system. KCN had a killing effect only at a 15--30 mM final concentration. The data show that the Budapest strain of T. pallidum is an anaerobic organism.     

Effect of dissolved carbon dioxide on penicillin fermentations: Mycelial growth and penicillin production

The effect of dissolved carbon dioxide on the specific growth rate and the penicillin production rate of Penicillium chrysogenum was examined experimentally. The dissolved carbon dioxide was found to inhibit the specific growth rate and the penicillin production rate when the aerated submerged penicillin fermentation was exposed to influent gases of 12.6 and 20% carbon dioxide, respectively. Upon exposure to influent gases of 3 and 5% carbon dioxide, no pronounced metabolic inhibition was noted.     

Effect of penicillin on GABA-gated chloride ion influx

To investigate the mechanism of penicillin-induced convulsions, we have studied the effects of penicillin G (PC-G) on GABA-gated chloride ion influx in brain microsac preparations of mice. In the presence of 10^–4 M GABA, PC-G inhibited GABA-gated chloride ion influx in a dose-dependent manner. The dose-response curve for GABA in the presence of 10^–3 M PC-G was shifted rightward and there was a decrease in maximum response. The inhibitory effects of PC-G were not reversed by RO 15-1788, an antagonist of benzodiazepine (BZ) receptors, but were reversed by washing the microsac membranes. Therefore, PC-G probably exerts its proconvulsant effect by inhibiting GABA-gated chloride ion influx. However, it appears not to act through the BZ receptor of the GABA/BZ receptor complex.