Oligomerized backbone pilin helps piliated Lactococcus lactis to withstand shear flow

Area of Science:

• Microbiology
• Bacterial Adhesion
• Surface Science

Background:

• Lactococcus lactis is a key bacterium in food fermentation.
• Bacterial adhesion is critical for colonization and biofilm formation.
• Pili, hair-like appendages on bacterial surfaces, are known to mediate adhesion.

Purpose of the Study:

• To investigate the role of Lactococcus lactis pili in bacterial adhesion to abiotic and biotic surfaces.
• To identify specific pili components involved in adhesion.
• To understand how pili influence bacterial detachment under shear stress.

Main Methods:

• Utilized native pili-displaying Lactococcus lactis strains and isogenic derivatives with modified pilin or sortase C genes.
• Evaluated surface physico-chemistry and morphology of bacterial cells.
• Assessed shear-flow-induced detachment of lactococcal cells from coated surfaces.

Main Results:

• Pili were demonstrated to be essential for L. lactis adhesion to both hydrophobic and mucin-coated surfaces.
• The accessory pilin PilC and the backbone pilin PilB (in polymerized form) play significant roles in adhesion.
• Pili act as anchoring sites, influencing cell orientation and reducing detachment under shear flow.

Conclusions:

• Pili are critical determinants of Lactococcus lactis adhesion to diverse surfaces.
• Specific pilin components, particularly PilC and polymerized PilB, are key mediators of this adhesion.
• Pili contribute to bacterial surface persistence by resisting shear forces.