n Vitro Evaluation of Antimicrobial Activity
An overlay method was used to assess the production of antimicrobial compounds by the 31 Bacillus strains against Gram-positive and Gram-negative enteropathogens (Table (Table2;2; Figure Figure2).2). Although antimicrobial activity was observed in a greater number of isolates, individual differences were evident in the degree of inhibition and spectrum of activity. In the case of S. Enteritidis, isolate NP122 generated the largest diameter of the zone of inhibition with 13.7 mm, followed by the strain AM0904 with a inhibition diameter of 12.0 mm. Activity against E. coli was more evident in isolates AM1010 and AM1012, both with a diameter of clearance of 20 mm. Interestingly, C. difficile was the most susceptible microorganism in the presence of almost all Bacillus spp. strains, with an average zone of inhibition of 19 mm for the 31 isolates, where the strain AM1010 produced larger pathogen-inhibition activity with a diameter of clearance of 28 mm