The combined antimicrobial activity of α-lactalbumin and thymol against Escherichia coli and Staphylococcus aureus

Thymol showed good antimicrobial activity, however, the poor aqueous solubility limits it to apply in food industry. α-Lactalbumin can be used to delivery hydrophobic molecules, then enhancing their biological activities. The study investigates the potential of α-lactalbumin to expand the application range of thymol, further to evaluate the antimicrobial activity of the α-lactalbumin-thymol complexation. Multi-spectroscopy techniques and computational simulations have confirmed the successful complexation, driving mainly by van der Waals force. The α-lactalbumin-thymol complexation exhibited the superior antimicrobial activity than thymol against Escherichia coli and Staphylococcus aureus , as indicated by lower or comparable minimum inhibitory concentration (336 μg/mL and 224 μg/mL, respectively), fewer colony forming units, and larger inhibition zone diameters. Furthermore, α-lactalbumin enhanced the degree of membrane damage by thymol. The complexation preserved no obvious cytotoxicity against HeLa cells. This study indicates that the α-lactalbumin-thymol complexation chelates hold promise as natural antimicrobial agents in the food processing industry.