Purpose: To investigate the role of the composition of the biofilm matrix produced by food-associated staphylococci for tolerance to cleaning and disinfection
Methods: Biofilm formation and detachment after exposure to enzymes degrading polysaccharide (Dispersin B), proteins (Trypsin and Proteinase K) and the cleaning agent hypochlorite were investigated using a microtiter plate-based assay. Susceptibility to the disinfectant benzalkonium chloride was tested in suspension and using a biofilm assay with stainless steel coupons (exposure at 20oC, 5 min). The presence of biofilm associated genes was investigated by whole genome sequencing.
Results: Three out of eight food-associated coagulase negative staphylococci appeared to produce a matrix composed of polysaccharide based on presence of the ica operon (known to encode a polysaccharide matrix), and results showing that biofilms were detached by dispersin B but not by proteinase K or trypsin. The remaining five strains studied appeared to produce a matrix mainly composed by protein as biofilms were detached by exposure to proteinase K or trypsin but not Dispersin B. These strains were ica negative and three isolates contained genes homologous to the biofim associated protein bap. All biofilms were detached by alkaline hypochlorite. Strains producing protein matrix were more susceptible to the disinfectant benzalkonium chloride both in suspension and biofilm than strains producing a polysaccharide type matrix.
Significance: Failure of sanitation in food and clinical environments may be related to staphylococci producing a polysaccharide-based biofilm matrix. The use of cleaning agents that can degrade the matrix components is crucial to eliminate staphylococcal biofilms.