Fermentacijski profil bakterijskih sojeva iz različitih izvora kao funkcionalnih starter kultura

master's thesis

• Title (english): Fermentation profile of bacterial strains from different sources as a functional starter culture
• Author: Ana-Marija Iveljić
• Mentor: Jasna Novak (mentor)
• Committee member: Tonči Rezić (predsjednik povjerenstva)
• Committee member: Andreja Leboš-Pavunc (član povjerenstva)
• Committee member: Marina Cvjetko Bubalo (član povjerenstva)
• 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: 2022-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Sukladno svjetskom trendu porasta primjene probiotika povećan je i znanstveni interes, ali i interes za aspekt legislative i kliničkih smjernica probiotičkih bakterija. Cilj ovog diplomskog rada je fenotipska karakterizacija bakterijskih sojeva iz različitih mikrookoliša slijedeći zahtjeve probiotičkog koncepta s fokusom na fermentacijski profil. Metabolička aktivnost bakterijskih sojeva ispitana je kontroliranom kultivacijom tijekom 48 sati pri 37 °C u obranom mlijeku. Statistički najznačajnija acidifikacija određena je nakon rasta Lactobacillus fermentum D12 u obranom mlijeku i u obranom mlijeku s različitim koncentracijama soli. Koagulacijski kapacitet potvrđen je fenotipski za sve ispitivane sojeve nakon 24 i 48 sati kultivacije u obranom mlijeku. Primjenom protokola za ciljanu ekstrakciju proteinaza, priređeni su ekstrakti proteina koji iskazuju kazeinolitičku aktivnost te analizirani SDS-PAGE metodom. Djelomično pročišćene proteinaze sojeva L. lactis ZGBP5-32 i ZGZA7-10 i u vrlo niskim koncentracijama pokazale su kazeinolitičku aktivnost. Modifikacija protokola ekstrakcije implementiranjem ultrafiltracije koja je doprinijela pročišćavanju proteinaza što je potvrđeno SDS-PAGE metodom za proteinske ekstrakte sojeva L. brevis D6 i SF9B, L. fermentum D12 i L. plantarum D13. Daljnja istraživanja bit će usmjerena na karakterizaciju bioaktivnih peptida uslijed proteazne aktivnosti odabranih kazeinolitičkih bakterija mliječne kiseline. Karakterizacija kazeinolitičkih bakterija mliječne kiseline u ovom radu može pridonijeti odabiru proteolitičkih sojeva kao mliječnih starter kultura.

Abstract (english)

In accordance with the worldwide trend of increased use of probiotics, scientific interest has increased, as well as the aspect of legislative framework and clinical guidelines. The aim of this thesis is the phenotypic characterization of bacterial strains from different microenvironments following the requirements of the probiotic concept with a focus on the fermentation profile. The metabolic activity of bacterial strains was tested by controlled cultivation for 48 hours at 37 °C in skimmed milk. The most statistically significant acidification was determined after the growth of Lactobacillus fermentum D12 in skimmed milk and in skimmed milk with different concentrations of salt. Coagulation capacity was confirmed phenotypically for all tested strains after 24 and 48 hours of cultivation in skimmed milk. By applying the protocol for the targeted extraction of proteinases, extracts of proteins showing caseinolytic activity were prepared and analyzed by the SDS-PAGE method. Partially purified proteinases of L. lactis strains ZGBP5-32 and ZGZA7-10 showed caseinolytic activity even in very low concentrations. The modification of the extraction protocol by implementing ultrafiltration contributed to the purification of proteinases, which was confirmed by the SDS-PAGE method for protein extracts of strains L. brevis D6 and SF9B, L. fermentum D12 and L. plantarum D13. Further research will be focused on the characterization of bioactive peptides due to the protease activity of selected caseinolytic lactic acid bacteria. The characterization of caseinolytic lactic acid bacteria in this work may contribute to the selection of proteolytic strains as lactic starter cultures.

• Keywords: probiotici; fermentacija; bakterije mliječne kiseline; proteinaza
• Keywords (english): probiotics; fermentation; lactic acid bacteria; proteinase
• Language: croatian
• URN:NBN: urn:nbn:hr:159:878205
• Study programme: Title: Molecular Biotechnology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka molekularne biotehnologije (magistar/magistra inženjer/inženjerka molekularne biotehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-02-24 13:46:26