Efeito de biossurfactantes na adesão de bactérias patogênicas em superfície de filmes flexíveis

Abstract

In the food industry there is a big concern about food contamination by bacterias, since small breaches can turn into a exposure and consenquently into a production contamination. Once the bacteria finds an adequate surface, it can settle and start the formation of bacterial biofilm. When the biofilm is formed, its removal becomes difficult. To prevent this to happen some antimicrobial substances can be used such as surfactin and rhamnolipid, they act breaking the bacterial cell killing it. Surfactin and rhamnolipid were tested against several microganisms in diferente plastics used in the food industry: P. aeruginosa, Bacillus cereus, Sthaphylococcus aereus, Salmonella sp and E. coli. This way, were realized adhesion tests, physical and chemical cell surface characterization tests, pathogenic microrganisms adhesion in plastics test, polystyrene microplates adhesion test and scanning eléctron microscopy. The microbial activity test showed that surfactin had better results than rhamnolipid, except for the treatment in S. aureus where rhamnolipd were more efficient, in the P. aeruginosa treatments there were no inhibition zone that proves its resistance against both surfactin and rhamnolipid. The pathogenic microrganisms adhesion in plastics test showed high efficiency against all microorganism except P.aeruginosa, which had less than 50% microbial adhesion reduction. In the polystyrene microplates adhesion test surfactin and ramnolipid showed its efficacy, but in a long-term experimentation the efficient dropped, showing that in cases where long time activity of surfactin and rhamnolipid are needed they will have low efficiency.