BINDING OF MUTAGENIC HETEROCYCLIC AMINES BY INTESTINAL AND LACTIC-ACID BACTERIA

Lactic acid bacteria have been reported to have antimutagenic/anticarc inogenic properties in vitro and in vivo. One possible mechanism for t his effect involves a physical binding of the mutagenic compounds to t he bacteria. The purpose of the present investigation was to study the binding capacity of eight human intestinal or lactic acid bacterial s trains for mutagenic heterocyclic amines formed during cooking of prot ein-rich food. Binding of the mutagens Trp-P-2, PhIP, IQ and MeIQx by the bacterial strains was analyzed by HPLC. There were only minor diff erences in the binding capacities of the tested strains but the mutage nic compounds were bound with markedly different efficiencies. Trp-P-2 was almost completely bound and the binding tended not to be of a rev ersible nature. The binding of PhIP, which reached about 50%, was impo rtant as PhIP is a major mutagen in the western diet. IQ and MeIQx wer e slightly less well bound. pH appeared to be of importance for the bi nding efficacy. Binding correlated well with the reduction in mutageni city observed after exposure of the heterocyclic amines to the bacteri al strains. The results indicate that cooked food mutagenic compounds, commonly found in the western meat-rich diet, can be bound to bacteri a from the normal intestinal microflora in vitro.