Inhibition of bacterial adherence on stainless steel coupons by surface conditioning with selected polar lipids

Polar lipids were recently found to have the surfactant property that could interfere with the bacterial adherence process during biofilm formation, a promising effect against the bacterial contamination on food processing surfaces. This study aimed to investigate the effect of surface conditioning of polar lipids such as phosphatidylcholine and sphingomyelin on stainless steel surfaces and subsequently on bacterial adherence. A confocal laser scanning microscope was used to examine formed conditioning layers and bacterial adherence. The thinnest conditioning layer was created by dilute skim milk and by sphingomyelin, while thicker layers were created by phosphatidylcholine, dilute buttermilk, and butter serum. Among surface conditioning treatments of stainless steel coupons, those performed with diluted buttermilk, butter serum, and polar lipids such as phosphatidylcholine, and sphingomyelin were able to scale down the adherence of Lactococcus lactis subsp. lactis NBRC 100676 and Leuconostoc mesenteroides subsp. cremoris NBRC 102479 compared to the surface conditioning with dilute skim milk. For both strains, the higher the phosphatidylcholine concentration (over 0.01%) and the longer the adhesion time (over 12.0 h), the more the adherence‐reducing ability of conditioned surfaces. The higher the sphingomyelin concentration used in surface conditioning, the higher the adherence‐reducing activity on stainless‐steel surfaces was at all adhesion times (0.5, 12.0, and 24.0 h). Our results suggested that, for short bacterial exposure period (0.5, 12.0, and 24.0 h), dilute buttermilk, butter serum, and individual polar lipids may have a bacterial adherence‐reducing effect, and can potentially be used for reducing biofilm formation. Surfaceconditioning by polar lipids could alter stainless steel surface property andsubsequently reduce bacterial adherence.