Then, aliquots of 2, 5, 10 and 20 mL of CFS were completely dried using a flow of nitrogen through evaporator workstation Turbovap at 35 C (Biotage, Madrid, Spain) and each one of these were resuspended in 1mL fresh sterile MRS broth so as to get concentrated solutions of 1:2; 1:5; 1:10, and 1:20.