Competitive and/or Cooperative Interactions of With in Dual-Species Biofilm Formation.

Microorganisms in dairy industries can form monospecies, dual-species, or multispecies biofilms, showing cooperative or competitive behaviors, which might contribute to the reduction of efficiency of cleaning and sanitization processes and eventually turn into a potential source of contamination. This study proposes to evaluate the behavior of in monospecies biofilms, cocultured with . The isolates were of dairy origin, and the selection occurred after studies of competition among species. The biofilm formations on AISI 304 stainless steel at 25°C in a stationary culture were analyzed to observe the cooperative or competitive interactions among species, as well as the effect of pre-adhered cells. Biofilm formation assays were performed in four experiments: Experiment 1: in the presence of strains of antagonistic substance producer (+); Experiment 2: extract of the antagonistic substance of ; Experiment 3: pre-adhered cells of ; and Experiment 4: pre-adhered cells of . Subsequently, cooperative behavior was observed by scanning electron microscopy. The monospecies biofilm counts of greater than 5 log colony-forming units (CFU)/cm were also observed in dual-species biofilms in the presence of (non-producers of antagonist substance), showing cooperative behavior between species. However, in the presence of antagonistic substance produced by , the counts were lower, 1.39 and 1.70 log CFU/cm ( > 0.05), indicating that the antagonistic substance contributes to competitive interactions. These data are relevant for the development of new studies to control in the dairy industry.