A fibronectin-binding protein (FbpA) of Weissella cibaria inhibits colonization and infection of Staphylococcus aureus in mammary glands.

Staphylococcus aureus (S. aureus) is a frequent cause of infections in both humans and animals. Probiotics are known to inhibit colonization of pathogens on host tissues. However, mechanisms for the inhibition are still elusive due to complex host-microbe and microbe-microbe interactions. Here, we show that reduced abilities of S. aureus to infect mammary glands in the presence of Weissella cibaria (W. cibaria) were correlated with its poor adherence to mammary epithelial cells. Such inhibition by W. cibaria isolates was at least partially attributed to a fibronectin-binding protein (FbpA) on this lactic acid bacterium. Three W. cibaria isolates containing fbpA had higher inhibitory abilities than other three LAB isolates without the gene. The fbpA-deficient mutant of W. cibaria isolate LW1, LW1ΔfbpA, lost the inhibitory activity to reduce the adhesion of S. aureus to mammary epithelial cells and was less able to reduce the colonization of S. aureus in mammary glands. Expression of FbpA to the surface of LW1ΔfbpA reversed its inhibitory activities. Furthermore, addition of purified FbpA inhibited S. aureus biofilm formation. Our results suggest that W. cibaria FbpA hinders S. aureus colonization and infection through interfering with the S. aureus invasion pathway mediated by fibronectin-binding proteins and inhibiting biofilm formation of S. aureus.