Inhibition of Streptococcus pyogenes biofilm by Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus
The human pathobiont Streptococcus pyogenes forms biofilms and causes invasive infections, such as pharyngotonsillitis and necrotizing fasciitis. Bacterial biofilms are more resilient to antibiotic treatment and new therapeutic strategies are needed to control biofilm-associated infections, such as recurrent pharyngotonsillitis. Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus are two bacterial commensals used for their probiotic properties. This study aimed to elucidate the anti-biofilm properties of L. plantarum and L. rhamnosus cell-free supernatants (LPSN and LRSN, respectively) on S. pyogenes biofilms grown in vitro in supplemented minimal medium. When planktonic or biofilm S. pyogenes were exposed to LPSN or LRSN, S. pyogenes survival was reduced significantly in a concentration-dependent manner and the effect was more pronounced on preformed biofilms. Enzymatic digestion of LPSN and LRSN suggested that glycolipid compounds might cause the antimicrobial effect. In conclusion, this study indicates that L. plantarum and L. rhamnosus produce glycolipid bioactive compounds that reduce S. pyogenes viability in planktonic and biofilm cultures.