Lactobacilli and bifidobacteria lectins as possible signal molecules regulating intra- and inter-population bacteria–bacteria and host–bacteria relationships. Part I. Methods of bacterial lectin isolation, physico-chemical characterization and some biological activity investigation

Lectins (natural or artificial nonimmunoglobulin origin proteins/glycoproteins) are able to bind noncovalently with carbohydrate targets. Lectins and lectin-like substances of lactobacilli (L. acidophilus K3III24; 100ash; NK1; L. plantarum 8RA3) and bifidobacteria (B. adolescentis MC42; B gallinarum, B. bifidum 1) have been investigated. Bacteria were grown in semi-anaerobic conditions in a casein-yeast broth. Medium was microfiltrated and ultrafiltrated for isolation of 30 kDa compounds which were then separated by isoelectric focusing in polyacrylamide gel in the presence of urea and sucrose. Components isolated were electrotransferred to immobillon P. Blots obtained were then treated with a set of biotinylated artificial linear homopolysaccharides revealed by streptavidin-peroxidase conjugate. Chemiluminescence registration of peroxidase bound to blots was performed using the ‘BioChemi System’ camera. A spectrum of different polysaccharide-binding individual components reacting with such homopolymers as mannan-alpha (phosphorylated or not), GalNAc-alpha-polysaccharide of mucin-like-type or galactan-beta (sulfated or not)-binding was found in lactobacilli and bifidobacteria. Lactobacilli produced a more limited spectrum of lectins or lectin-like compounds with higher affinities to polysaccharides tested than bifidobacteria having more extended pI polysaccharide-binding activity spectrum. Interaction of isolated lectins with T and B lymphocytes, macrophages, and thrombocytes was demonstrated. The importance of lactobacilli and bifidobacteria lectins/lectin-like components and their effector complexes in cell mitoses, blood coagulation, aerobic metabolic reactions, and other biological activities is discussed.