Quorum Quenching in copper-tolerant Papiliotrema laurentii strains

Abstract

In the rhizosphere, the role of yeasts in microbial interactions and signaling is an open question. To study the influence of fungicides on yeast inactivation of N-acyl homoserine lactone quorum sensing signals, we evaluated the resistance of Papiliotrema laurentii strains from tomato rhizosphere to CuSO4 and Cu2(OH)3Cl fungicides, and the copper effect on yeast quorum quenching. Copper resistance profiles and colony morphologies allowed the distinction of two groups of P. laurentii strains: mucoid, green and resistant, and brown-orange and more sensitive. Most of the strains inactivated C6-HSL and C10-HSL QS signals. Inactivation and copper divided the strains in three with weak activity independently of the metal, and 11 with activities affected by copper. The lack of alkalinization allows the hypothesis of an enzymatic inactivation of the signals. These results suggest that yeasts contribute to communications in the rhizosphere, and that copper fungicides can modify their interactions with other rhizosphere microorganisms.