[Protein fingerprinting as a method for strain-specific differentiation of technologically useful Lactobacillus...

Lactobacilli are often used in products of animal origin because of their technological properties and as protective cultures against pathogenic microorganisms, however they are supposed to be related to human infections as well. Therefore 39 strains of species that are in biotechnological usage, including the type strains, and some clinical isolates were investigated. 9 strains of L. acidophilus, 7 of L. gasseri and 23 strains of L. rhamnosus were tested. Biochemical and physiological properties were proved by classical tests. Analysis of the total soluble cytoplasmatic protein patterns was performed with diamine silver staining, a technique not previously applied to lactobacilli. Classical tests were able to confirm all strains as belonging to one of the three species. Analysis of protein patterns allowed to differentiate between strains of the same species. In case of L. acidophilus biotechnologically used strains and clinical isolates were clustered separately. L. rhamnosus formed three clusters. SDS-PAGE of proteins together with diamine silver staining seems to be helpful to detect intra-species differences. It was stated, that technologically used strains of lactobacilli could clearly be differentiated from another and also from clinical isolates.