title: Unraveling the role of surface mucus-binding protein and pili in muco-adhesion of Lactococcus lactis.
abstract: Adhesion of bacteria to mucus may favor their persistence within the gut and their beneficial effects to the host. Interactions between pig gastric mucin (PGM) and a natural isolate of Lactococcus lactis (TIL448) were measured at the single-cell scale and under static conditions, using atomic force microscopy (AFM). In parallel, these interactions were monitored at the bacterial population level and under shear flow. AFM experiments with a L. lactis cell-probe and a PGM-coated surface revealed a high proportion of specific adhesive events (60%) and a low level of non-adhesive ones (2%). The strain muco-adhesive properties were confirmed by the weak detachment of bacteria from the PGM-coated surface under shear flow. In AFM, rupture events were detected at short (100-200 nm) and long distances (up to 600-800 nm). AFM measurements on pili and mucus-binding protein defective mutants demonstrated the comparable role played by these two surface proteinaceous components in adhesion to PGM under static conditions. Under shear flow, a more important contribution of the mucus-binding protein than the pili one was observed. Both methods differ by the way of probing the adhesion force, i.e. negative force contact vs. sedimentation and normal-to-substratum retraction vs. tangential detachment conditions, using AFM and flow chamber, respectively. AFM blocking assays with free PGM or O-glycan fractions purified from PGM demonstrated that neutral oligosaccharides played a major role in adhesion of L. lactis TIL448 to PGM. This study dissects L. lactis muco-adhesive phenotype, in relation with the nature of the bacterial surface determinants.
authors.affiliation: Université de Toulouse; INSA,UPS, INP; LISBP, Toulouse, France ; INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, Toulouse, France ; CNRS, UMR5504, Toulouse, France ; CNRS, LAAS, Toulouse, France ; CNRS, ITAV-UMS3039, Toulouse, France ; Université de Toulouse, LAAS, Toulouse, France.
authors.forename: Doan Thanh Lam
authors.initials: DT
authors.lastname: Le
authors.forename: Thi-Ly
authors.initials: TL
authors.lastname: Tran
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Duviau
authors.forename: Mickael
authors.initials: M
authors.lastname: Meyrand
authors.forename: Yann
authors.initials: Y
authors.lastname: Guérardel
authors.forename: Mickaël
authors.initials: M
authors.lastname: Castelain
authors.forename: Pascal
authors.initials: P
authors.lastname: Loubière
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Chapot-Chartier
authors.forename: Etienne
authors.initials: E
authors.lastname: Dague
authors.forename: Muriel
authors.initials: M
authors.lastname: Mercier-Bonin
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D005752:Gastric Mucins / Q000378:metabolism*; D013294:Lactococcus lactis / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009093:Mucus / Q000378:metabolism / Q000382:microbiology* / Q000502:physiology; D013499:Surface Properties; D013552:Swine
chemical_list: D002352:Carrier Proteins; D005752:Gastric Mucins; D008565:Membrane Proteins