RESUMO
OBJECTIVE: To determine the mechanism of growth inhibition of Aggregatibacter actinomycetemcomitans by Maillard reaction products (MRP). DESIGN: Growth and cell viabilities in the presence or absence of MRP were measured for both the rough and smooth variants of the bacteria. Effects of addition of ferrous and ferric ions on the inhibition of the bacteria by MRP were determined. RESULTS: MRPs decreased the extent of complex formation of Chrome Azurol S with iron suggesting that MRPs can chelate iron effectively. The chelation causes growth inhibition of both the rough and smooth strains. At low concentrations of the inhibitor, lag time was extended by approximately 12 h while at high concentrations, cells were killed, decreasing cell viability by up to 8 orders of magnitude. Growth of both the rough and smooth strains could be restored to original level by addition of iron. For the rough strain, both ferrous and ferric ions could relieve the inhibition by MRP while for the smooth strain only ferrous ion was effective. CONCLUSION: MRPs inhibit the growth of A. actinomycetemcomitans by chelating iron and the inhibition can be relieved by addition of iron.
