Antimicrobial resistance against commonly used antibiotics is one of the most serious global public health threats in this century. Moreover, the use of antibiotics also has detrimental effect on human intestinal microbiome diversity due to microbicidal activity against beneficial commensal bacteria. Lectins are proteins that specifically and reversibly bind to carbohydrates and exert anti-microbial activity, potentially representing an alternative strategy to fight against infections by resistant microbial strains. In our study, we recombinantly expressed and isolated lectin KKP from Coprinopsis cinerea. We evaluated its effect on growth and adhesion of pathogenic and commensal microorganisms. Lectin KKP reduced the growth capacity of pathogenic bacteria Salmonella infantis and an additive effect of KKP and protease inhibitors was observed reducing the adhesion of this bacteria. In contrast, lectin KKP augmented the adhesion of commensal bacteria, especially Lactobacillus species. The overall effect of lectin KKP on growth and adhesion of microorganisms was very similar for the strains of the same species but varied significanly between different species, pointing towards very specific target recognition and binding. We proved that lectin KKP specifically binds to the cell wall proteins and extracellular proteins of Lb. plantarum strains. In summary, lectin KKP could potentially be used as a natural, alternative anti-microbial substance against Salmonella infantis infection. Furthermore, it could also be used as a natural supplement to antibiotic therapy that preserves the growth and fuction of commensal bacteria.
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