Growth, morphology and surface properties of Listeria monocytogenes Scott A and LO28 under saline and acid environments.
OBJECTIVE
The effect of salt and acid on the growth and surface properties of two strains of Listeria monocytogenes was investigated.


RESULTS
Medium acidification and NaCl supplementation induced a marked increase in the lag and growth times (up to fivefold higher) and a decrease in the maximal optical density. Due to a strong synergic effect of pH and NaCl, growth was only detected after 280 h incubation for Scott A and not detected after 600 h for LO28 at pH 5.0 and 10% NaCl. Furthermore, the addition of NaCl in acidic conditions gave rise to cell filamentation and cell surfaces became strongly hydrophilic.


CONCLUSIONS
Some L. monocytogenes strains subjected to high NaCl concentrations in acidic conditions are able to grow but may present altered adhesion properties due to modification of their surface properties.


CONCLUSIONS
This study highlighted that L. monocytogenes do represent a hazard in acid and salted foods, such as soft cheese.
Bereksi
N
N
Institut National de la Recherche Agronomique, Laboratoire de Génie des Procédés et Technologie Alimentaires, 369 Rue Jules Guesde, BP 39, F-59651 Villeneuve d'Ascq Cedex, France.
Gavini
F
F
Bénézech
T
T
Faille
C
C
D001422:Bacterial Adhesion; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000254:growth & development* / Q000648:ultrastructure*; D012965:Sodium Chloride; D012997:Solvents; D013499:Surface Properties
D012997:Solvents; D012965:Sodium Chloride