This work demonstrated that the pre-conditioning with biosurfactants
can delay the adhesion of food pathogenic bacteria even
in a nutrient rich environment. The conditioning of polystyrene
with surfactin and rhamnolipids reduced the hydrophobicity of the
surface. The anti-adhesive effect shows to be dependant on
bacterium as well the biosurfactant type and concentration. L.
monocytogenes was the most susceptible microrganism since its
adhesion was significantly reduced by both biosurfactants.
However, the best resultwas obtained by the pre-conditioning with
rhamnolipid 1.0% against S. aureus (67.8% reduction). Biosurfactants
were less effective on reducing adhesion of mixed culture when
comparing with pure cultures of the bacteria. The biosurfactants
also showed potential as agents to disrupt pre-formed biofilms of
the food pathogens furthermore surfactin was more efficient than
rhamnolipids. The time of contact and the concentration of biosurfactant
have influenced the ability to disrupt the biofilms.
Further studies should be conducted to evaluate the effect of pH,
ionic force, temperature and nutrients on the hydrophobicity of the
surfaces pre-conditioned with biosurfactants as well as their effect
on biosurfactant molecular aggregation. The biofilm eradication
should be assessed with older biofilms, low concentrations of
biosurfactants and short contact times.