Influence of phenol, p-cresol and indole on growth and survival of intestinal lactic acid bacteria

Some intestinal bacteria can produce many genotoxic, mutagenic and carcinogenic substances. The major products of the bacterial aromatic amino acids fermentation-phenolic and indolic compounds which are responsible for colon cancer development are accumulated in the colon. The effect of phenol, p-cresol and indole (2, 20 and 100 microg/ml doses) on growth and survival of four strains of intestinal lactic acid bacteria was studied. Growth of bacteria was not affected by any of the concentrations of phenol and p-cresol tested. The growth of 2 strains was slightly inhibited by 100 microg/ml of indole. There was no influence of phenol and p-cresol on survival of lactic bacteria until 120 h and specific reaction to carcinogens depending on strain was observed after that incubation time. Indole concentrations 20 and 100 microg/ml appeared to be toxic for all tested strains but just after 24, 48 or 72 h of incubation depending on the strain. In total, 2 microg/ml of indole had a very little effect.