4. Conclusion
All the data obtained from surface analysis by CAM, AFM,
PM-IRRAS and XPS suggest that biosurfactants from L. helveticus
1181 and P. fluorescens 495 strains modify the stainless
steel surfaces in different ways: Pf495 biosurfactant conditioning
results in a thin homogeneous layer of organic material and
Lb conditioning leaves a rather smaller amount of adsorbed
molecules, in a more heterogeneous layer. Both biosurfactants
induce a net segregation of chromium towards the surface. In
our experimental conditions, this bioconditioning of stainless
steel surfaces led to a considerable decrease of the biocontamination
by strains of L. monocytogenes, averagely hydrophobic or
hydrophilic associated with a more or less strong electron donor
character. These results could be attributed to modifications in
the acid base characteristic of solid surfaces [5].
As a consequence, in our experimental conditions, we have
demonstrated the efficiency of conditioning a stainless steel surface
by a layer of biosurfactants, notably that produced by L. helveticus,
a strain of technological interest, on the adhesion of four
strains of L. monocytogenes presenting very different physicochemical
phenotypes. It is noticeable that this anti-adhesive
effect was observed by using biosurfactants released as well
by gram-negative bacteria (Pseudomonas) as by gram-positive
bacteria (Lactobacillus). This work shows the real antiadhesive
power of these biological surface-active compounds against biocontamination
of metallic surfaces by undesirable germs like L.
monocytogenes. The bioconditioning of solid surfaces, leading
to a significant decrease in listerial contamination, makes obvious
4. Conclusion
All the data obtained from surface analysis by CAM, AFM,
PM-IRRAS and XPS suggest that biosurfactants from L. helveticus
1181 and P. fluorescens 495 strains modify the stainless
steel surfaces in different ways: Pf495 biosurfactant conditioning
results in a thin homogeneous layer of organic material and
Lb conditioning leaves a rather smaller amount of adsorbed
molecules, in a more heterogeneous layer. Both biosurfactants
induce a net segregation of chromium towards the surface. In
our experimental conditions, this bioconditioning of stainless
steel surfaces led to a considerable decrease of the biocontamination
by strains of L. monocytogenes, averagely hydrophobic or
hydrophilic associated with a more or less strong electron donor
character. These results could be attributed to modifications in
the acid base characteristic of solid surfaces [5].
As a consequence, in our experimental conditions, we have
demonstrated the efficiency of conditioning a stainless steel surface
by a layer of biosurfactants, notably that produced by L. helveticus,
a strain of technological interest, on the adhesion of four
strains of L. monocytogenes presenting very different physicochemical
phenotypes. It is noticeable that this anti-adhesive
effect was observed by using biosurfactants released as well
by gram-negative bacteria (Pseudomonas) as by gram-positive
bacteria (Lactobacillus). This work shows the real antiadhesive
power of these biological surface-active compounds against biocontamination
of metallic surfaces by undesirable germs like L.
monocytogenes. The bioconditioning of solid surfaces, leading
to a significant decrease in listerial contamination, makes obvious
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