Critical condition for the occurrence of a noise-reduction effect

Based on a copy number control model of bacterial plasmid, the internal noise near a given steady state is investigated by using the linear noise approximation. All the parameters are restricted to a certain region so that the time spent near the steady state is long enough and the absorbing state can be neglected. For the noise in the plasmid molecules, a transition occurs with increasing the noise in the signal molecules under certain conditions. A noise-reduction mechanism, noise suppression by noise, is found. More importantly, the critical condition for the occurrence of the noise-reduction effect is given in our theoretical treatment.