Biosurfactants in the Food Industry - Biosurfactants: Research Trends and Applications - page 180

could remain on equipment surfaces and survive for prolonged periods (Cloete et al.,
2009), so it is imperative to search for new biofilm controlling strategies.
Some studies have shown that the conditioning of surfaces with BS can sig-
nificantly reduce microbial adhesion and inhibit or reduce subsequent biofilm
development.
Surfactin was tested by Mirelles et al. (2001) as an antiadhesive agent to inhibit
biofilm development on catheters by Salmonella enterica, Escherichia coli, Proteus
mirabilis , and P. aeruginosa . The total inhibition by preconditioning the surface was
observed for all bacteria, but not for P. aeruginosa .
The preconditioning of stainless steel and poly(tetrafluoroethylene) PTFE sur-
faces with a BS obtained from P. fluorescens) inhibits the L. monocytogenes L028
adhesion. A significant reduction (>90%) was attained in microbial adhesion levels
on stainless steel, whereas no significant effect was observed in PTFE (Meylheuc
et al., 2001). Further work demonstrated that the prior adsorption of P. fluorescens)
surfactant on stainless steel also favored the bactericidal effect of disinfectants
(Meylheuc et al., 2006a). The ability of adsorbed BSs, obtained from gram-negative
( P. fluorescens) ) and gram-positive ( L. helveticus ) bacteria isolated from foodstuffs,
on inhibiting the L. monocytogenes adhesion to stainless steel was also investigated.
Adhesion tests showed that both BSs were effective, strongly decreasing the sur-
face contamination level. The antiadhesive biological coating reduced both the total
adhering flora and the viable/cultivable adherent L. monocytogenes on stainless steel
surfaces (Meylheuc et al., 2006b).
The adhesion of E. coli CFT073 and Staphylococcus aureus ATCC 29213 to
polystyrene was reduced by 97% and 90% respectively using BSs obtained from
Bacillus subtilis and B. licheniformis . The antiadhesive activity was observed either
by coating the surface or by adding the BS to the inoculum (Rivardo et al., 2009).
A BS obtained from Lactobacillus paracasei A20 was able to reduce adhesion of
S. aureus to polystyrene by 76.8%, whereas it showed low activity against P. aerugi-
nosa and E. coli (Gudiña et al., 2010).
An interesting work regarding the antiadhesive activity of BSs was conducted by
Shakerifard et al. (2009). The authors evaluated the ability of lipopeptide surfactants
from B. subtilis to modify the hydrophobicity of Teflon and stainless steel surfaces
and its correlation with the adhesion of B. cereus spores. They concluded that there is
a good correlation between surface hydrophobicity modifications promoted by BSs
and attachment of spores. The best results were shown to iturin A, which reduce the
adhesion of spores to Teflon by 6.5-fold at 100 mg/L.
The prior adsorption of surfactin on polypropylene and stainless steel surfaces
reduced the adhesion the food pathogens L. monocytogenes , S. enteritidis , and
Enterobacter sakazakii . The number of adhered cells of L. monocytogenes on stain-
less steel was reduced by two log units (Nitschke et al., 2009). Zeraik and Nitschke
(2010) evaluated the effect of temperature on antiadhesive activity of surfactin
against S. aureus , L. monocytogenes , and M. luteus in polystyrene surfaces. The
authors demonstrated that the decrease in temperature increases the antiadhesive
activity of surfactin especially at 4°C (63%-66% reduction), which is important once
pathogens like L. monocytogenes can grow at this temperature.