[en] Presently work, we prove if the protein psi B suppresses the indirect recombinogenesis of lambda when inhibiting the induction of the system bacterial SOS. This experimental model's advantage is that it allows to exclude the activity of co protease of RecA selectively without affecting the activity of recombinases of the same one, making possible the analysis of the paper that play both functions in the phenomenon. The results show that the inhibition of the activity of co protease of RecA doesn't suppress the indirect recombinogenesis of lambda. (Author)