S-layer as mediator of probiotic activity in Lactobacillus strain

Primjenom probiotika može se značajno utjecati na sastav mikrobne zajednice intestinalnog trakta. Probiotici mogu također onemogućiti rast patogena te utječu na učvršćivanje barijere crijevne sluznice. Stoga je cilj ovog rada bio istražiti probiotičko djelovanje odabranih sojeva iz roda Lacobacillus koji na površini svojih stanica imaju sloj S-proteina te je ispitana njihova uloga primjenom in vitro modela koji simuliraju uvjete gastrointestinalnog trakta. Provedeno je istraživanje u kojem je dokazana zaštitna uloga S-proteina odabranih Lactobacillus sojeva u preživljavanju simuliranih uvjeta GIT-a zbog smanjene smrtnosti stanica sa S-proteinom u usporedbi sa stanicama istih sojeva kod kojih je S-protein uklonjen. Također je dokazano da stanice Lactobacillus sojeva s prisutnim S-proteinima pokazuju veću sposobnost autoagregacije i pridonose povećanoj sposobnosti koagregacije sa test-mikroorganizmima E. coli 3014 te Salmonella enterica serovar Typhimurium FP1. Prilikom ispitivanja adhezije odabranih Lactobacillus sojeva na proteine ekstracelularnog matriksa (ECM) svi odabrani Lactobacillus sojevi su nakon uklanjanja S-proteina s površine stanica pokazali smanjenu sposobnost adhezije te je primjenom MATS metode pokazano je da kod bakterijskih stanica ispitanih Lactobacillus sojeva sa slojem S- proteina uočen veći postotak adhezije na heksan u usporedbi sa stanicama istih sojeva bez S- proteina čime je dokazan hidrofoban karakter površne stanice. Također S-protein ima i zaštitnu ulogu u procesu liofilizacije što je dokazano smanjenom smrtnosti Lactobacillus sojeva kod kojih je prilikom provođenja procesa liofilizacije bio prisutan S-proteinApplication of probiotics can significantly improve the composition of the microbial community of the intestinal tract. Probiotics may also unable the growth of pathogens and influence on bracing the intestinal mucosa barrier. The main goal of this study was to research probiotic effect of selected Lactobacillus strains which have S-layer and to test their function by application in vitro model in which are simulated conditions of gastrointestinal tract. The research was taken in which was proved protective function of S-layer selected Lactobacillus strains in surviving simulated GIT conditions because of reduced cell mortality containing S-layer comparing to cells without S-layer. It was also proven that cells of Lactobacillus strains with S-layer show higher capacity of autoaggregation and contribute to higher capacity of coaggregation with test microorganisms E. coli 3014 and Salmonella enterica serovar Typhimurium FP1. During the examination of adhesion selected Lactobacillus strains on proteins of extracellular matrix (ECM) all selected Lactobacillus strains showed reduced ability of adhesion after removing S-layer. Using MATS method, it was also shown that cells containing S-protein had higher percentage of adhesion on hexane comparing to cells of the same strain without S-protein which proved hydrophobic character of cell surface. S-protein also has protective role during the lyophilization process which is proved by reduced mortality of Lactobacillus strains in whom was during the lyophilization process present S-protein