Inhibition of Bacillus megaterium by a trimethylamine oxide-associated browning reaction product.

Heated combinations of trimethylamine oxide (TMAO) and culture media (tryptone, glucose, yeast extract broth or a defined minimal medium), or heated TMAO and glucose, contained substance(s) that inhibited growth of Bacillus megaterium. Inhibition was expressed primarily as an increase of the lag phase of growth; the logarithmic growth rate was comparable to control cultures. The addition of unheated TMAO to the culture media had no effect on growth. Results suggested that TMAO was decomposed during heating and that dimethylamine, one of the degradation products, reacted with glucose by a Maillard-Amadori reaction to produce the inhibitory substance(s).