Effect of Flavonoids on the Ecology of Enterobacteria

The effect of flavonoids, natural plant metabolites, on the growth and viability of enterobacteria was studied using S. typhimurium and E. coli strains defective in some components of the DNA repair system. The minimal inhibitory concentrations of several flavonoids were measured. These agents were shown to have a weak bactericidal and a marked bacteriostatic effect, the latter increasing under anaerobic conditions. It is proposed that the mechanism of the bacteriostatic action of flavonoids is based on topoisomerase II inhibition. On the basis of these results, the ability of flavonoids to differentially suppress bacterial growth and their probable influence on the ecology of microorganisms (the formation, species composition, and ecological balance of natural microbial communities) are discussed.