Function of S-layer proteins in autoaggregation and coaggregation of Lactobacillus strains

Osim primjene u industrijskim fermentacijama, bakterije mliječne kiseline (BMK) čine važan dio mikrobne populacije prirodnih ekosustava poput urogenitalnog i gastrointestinalnog trakta ljudi i životinja. Pojedini sojevi BMK su definirani i kao probiotici koji doprinose poboljšanju zdravlja na prirodan način, a autoagregacija i koagregacija BMK su važna svojstva koja se iskazuju u definiranju svojstva adhezije probiotičkih sojeva. U ovom radu istražena je uloga S-proteina (eng. Surface layer proteins) u autoagregaciji BMK koji na površini svojih stanica imaju parakristalni sloj S–proteina: Lactobacillus brevis D6, L. brevis ZG1, L. brevis SF9B i L. paraplantarum SF15B. Istražena je i koagregacija navedenih sojeva BMK s patogenom Salmonella eneterica serovar Typhimurium što može biti važno svojstvo u kompetitivnoj ekskluziji patogenih bakterija u GIT. Svi probiotički sojevi iskazuju veću sposobnost autoagregacije i koagregacije kada na svojoj površini sadrže S–proteine, nego kada su im ti proteini bili uklonjeni. Stoga se može zaključiti da S–proteini imaju važnu ulogu u agregaciji BMK.Beyond their involvement in industrial fermentations, LAB make part of natural ecosystems such as the urogenital or the gastrointestinal tract of humans and animals. Some strains of LAB are also defined as probiotics which increase health in natural way. Autoaggregation and coaggregation of LAB are very important properties which are stated in the definition of adhesion of probiotic strains. In this work, function of S-layer proteins in autoaggregation of LAB that have paracrystalline arrays of proteins has been examined: Lactobacillus brevis D6, L. brevis ZG1, L. brevis SF9B and L. paraplantarum SF15B. Also, function of S-layer proteins in coaggregation of these strains LAB with pathogen Salmonella eneterica serovar Typhimurium has been examined. LAB probiotic strains that have S-layer proteins on their surface exhibit greater autoaggregation and coaggregation ability than LAB strains which S-layer proteins were removed. Therefore, the conclusion is that S-layer proteins have very important function in aggregation of LAB