A simultaneous effect of some amino acids and metals on the activity of Desulfotomaculum ruminis bacteria in the process of microbiological sulphate reduction is studied. It has been established that the simultaneous presence of valine and one of the metals tested (cadmium, chromium or molybdenum) produces a synergetic effect of enhanced inhibitory effect relative to the effect at the presence of only one of these components. Moreover, serine, aspargine and isoleucine have insignificant effect on the desulfurication of sulphates, but the efficiency of this process significantly depends on the presence of metal ions in the medium.