Probiotic characteristics of strain Lactobacillus brevis SF15b expressing S-proteins

Abstract

Probiotici su živi mikroorganizmi koji, kada su prisutni u odgovarajućem broju, poboljšavaju zdravlje domaćina. Bakterije mliječne kiseline, među kojima se posebno ističu bakterije iz roda Lactobacillus, su najbolji modeli za probiotičku upotrebu te karakterizaciju pozitivnih učinaka. Cilj ovog rada bio je ispitati probiotička svojstva soja Lactobacillus brevis SF15B koji eksprimira S-proteine. Pritom se kao pozitivna kontrola koristio soj L. helveticus M92 koji eksprimira S-proteine, dok je negativna kontrola bio soj L. plantarum D13 koji navedene proteine ne eksprimira. Osim S-proteina, na površini stanica ispitivanog soja nalaze se i SLAP (Eng. Surface-Layer Associated Proteins). Uloga S-proteina u probiotičkom djelovanju soja SF15B ispitana je iz aspekta adhezije na mucin, prilikom čega je dokazano da prisutnost sloja S-proteina pridonosi boljim adhezijskim svojstvima. Osim toga, soj L. brevis SF15B ima sposobnost preživljavanja u pojedinim nepovoljnim uvjetima koji mogu vladati u ljudskom gastrointestinalnom traktu te pokazuje značajnu proteolitičku aktivnost.Probiotics are live microorganisms which, when administered in adequate amount, confer a health benefit on the host. Lactic acid bacteria, especially bacteria of the genus Lactobacillus, are of first choice microorganisms for probiotic application and characterization of their effect on human health. The aim of this study was to examine probiotic properties of the strain Lactobacillus brevis SF15B which expresses S-layer proteins. Strain L. helveticus M92, which also contains layer of S-proteins on the surface of the bacterial cells, was used as positive control, while strain L. plantarum D13, which doesn`t express mentioned proteins, was used as negative control. Besides S-layer proteins, on the cell surface of strain SF15B there are also SLAPs (Eng. Surface-Layer Associated Proteins). The role of S-layer proteins in probiotic activity of strain SF15B was examined from the aspect of adhesion to mucin, during which it was proven that the presence of S-layer proteins contributes to better adhesion properties. In addition, strain L. brevis SF15B has the ability to survive in the various rigorous conditions which are present in the human gastrointestinal tract and exhibits significant proteolytic activity