Do Broth Culture Filtrates Contain a Bacterial Growth-Inhibiting Substance?

Abstract

The effect of bacterial filtrates on growth of bacterial cultures is due to exhaustion of nutrient material. If nitrates prepared from broth cultures, pancreatin digested broth, or bacterial-cell solutions are added to varying proportions of nutrient broth there is a diminution of growth of inoculated organisms equal to, or less than, that observed when distilled water or saline is used as diluent. Broth culture filtrates of the organisms used failed to support a normal growth of either the same organism, Escherichia coli, or a heterologous organism, Staphylococcus albus.