A Bacteriotoxic Substance in Autoclaved Culture Media Containing Glucose and Phosphate

摘要

A bacteriocoxic factor or factors is formed in a simple, chemically defined culture medium for V. cbolerac when glucose and phosphate are present during heat sterilization. Depending upon its concentration and the size of the inocu¬lum, the factor may be rapidly bactericidal, or merely bacteriostatic; if delayed initiation of growth occurs in its presence there is only a minor influence upon the growth rate and total cell crop. Selection of resistant mutants or enzymatic adaptation does not appear to account for delayed growth.nThe same or a similar factor is present in autoclaved neutral solutions of glucose and phosphate, from which it can be removed by adsorption with norite charcoal, or partly extracted with ether. A nonvolatile residue of an ether extract, less than 1 µg. of which inhibits growth of small inocula of V. cbolerae, contains carbonyl compounds upon which its inhibitory activity appears to depend. The factor inhibits several other grain-negative species, including strains of Salmonella and Escherichia, but possesses low activity for strains of Aerobacter and Pseudomonas. The inhibition produced by the factor is counteracted by reducing agents, by certain carbonyl reagents, and by small quantities (0.1 to 10 µg.) of peptone and yeast extract.