Abstract: Lipoic acid (LA) is a class of natural vitamin-like compounds widely distributed in fruits and vegetables. This study investigated the effects of LA on the swimming and swarming motility and biofilm-forming capacity of Cronobacter sakazakii and its ability to adhere and invade the host cells as well as to survive and replicate in macrophages. The results showed that LA could effectively inhibit C. sakazakii with minimum inhibitory concentrations (MICs) of 5.00 mg/mL for three standard strains and three isolated strains, and sub-minimum inhibitory concentrations (SIC) of 30 and 60 μg/mL for C. sakazakii ATCC 29544. The SICs of LA inhibited the swimming and swarming motility and biofilm-forming capacity of C. sakazakii, and its ability to adhere and invade Caco-2 cells. In addition, the ability to survival and replicate in mouse macrophages RAW 264.7 was suppressed by LA at SICs. These findings suggest that LA can effectively inhibit the growth of C. sakazakii and significantly reduce its infection ability. LA has the potential to act as a dietary supplement to prevent or control foodborne diseases associated with C. sakazakii.

Key words: lipoic acid; Cronobacter sakazakii; anti-infection; biofilm; Caco-2 cell