Zaštitna uloga S-proteina kod bakterijskih sojeva vrste Lactobacillus brevis

master's thesis

• Title (english): Protective role of S-layer proteins in bacterial strains of Lactobacillus brevis
• Author: Ivan Povrženić
• Mentor: Jagoda Šušković (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Antibiotic, Enzyme, Probiotic and Starter Cultures Technology); Zagreb
• Defense date and country: 2012-07-12, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Pod pojmom probiotik podrazumijeva se pojedinačna ili mješovita kultura živih mikroorganizama koji primjenjeni u ljudi ili životinja blagotvorno djeluju na domaćina poboljšavajući mu svojstva autohtone crijevne mikroflore. Cilj ovog rada bio je ispitati utjecaj S-proteina na probiotička svojstva L. brevis D6, L. brevis SF15B, L. brevis K1, L. brevis ZG1_K7. Najprije je ispitan utjecaj S-proteina na preživljavanje L. brevis sojeva u simuliranim uvjetima GIT. Prema dobivenim rezultatima prisutnost S-proteina na površini stanica smanjuje smrtnost stanica u simuliranim uvjetima GIT. Svi ispitani bakterijski sojevi, sa S-proteinom, pokazuju visok postotak autoagreagacije te viši postak koagregacije sa bakterijom Salmonella eneterica serovar Typhimurium u odnosu na sojeve kojima je uklonjen sloj S-proteina. Za postizanje pozitivnog učinka na zdravlje domaćina, potrebno je u organizam unijeti točno definirani broj živih probiotičkih bakterija u koncentriranom, praškastom pripravku koji se može prirediti liofilizacijom. Stoga je u ovom radu provedena liofilizacija L. brevis sojeva. Nakon liofilizacije broj živih stanica sa slojem S-proteina bio je veći od broja živih stanica kojima je sloj S-proteina bio uklonjen prije liofilizacije, što ukazuje na zaštitnu ulogu S-proteina u stresnim uvjetima sušenja bakterijskih stanica liofilizacijom.

Abstract (english)

Probiotics are defined as mono or mixed cultures of living microoganisms which, when applied to animal or man, beneficially affect the host by improving the properties of the indigenous microflora. The aim of this study was to investigate the influence of S-layer proteins on probiotic properties of L. brevis D6, L. brevis SF15B, L. brevis K1, L. brevis ZG1_K7. Primarily, in this study was meant to examine the effect of S-layer proteins on the survival of L. brevis strains in simulated GIT conditions. The results indicated that the presence of S-layer proteins reduces cell death in simulated GIT conditions. All bacterial strains tested, with the S-layer proteins, show a high percentage of autoaggreagtion and coaggregation with bacteria Salmonella enteric serovar Typhimurium compared to strains which removed the S-layer proteins. To achieve a positive impact on the health of the host, there is need to ingest a well-defined number of living probiotic bacteria in a concentrated, powdered preparation that can be prepared by lyophilization. Therefore, lyophilization of L. brevis strains was carried out in this study. After lyophilisation the number of living cells, with S-layer proteins, was higher than number of living cells where the S-layer proteins were removed before the lyophilisation, suggesting a protective role of S-layer proteins under stress by lyophilisation drying of bacterial cells.

• Keywords: probiotici; sloj S-proteina; autoagregacija; koagregacija; liofilizacija; simulirani uvjeti gastrointestinalnog trakta
• Keywords (english): probiotic; S-layer proteins; autoaggregation; coaggregation; lyophilisation; simulated conditions of gastrointestinal tract
• Language: croatian
• URN:NBN: urn:nbn:hr:159:750899
• Study programme: Title: Bioprocess Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva (magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-08 10:11:17