Enterococcus sojevi iz mikrobioma sira

master's thesis

• Title (english): Enterococcus strains from the cheese microbiome
• Author: Amalija Blagajac
• Mentor: Jasna Novak (mentor)
• Committee member: Andreja Leboš-Pavunc (predsjednik povjerenstva)
• Committee member: Tonči Rezić (član povjerenstva)
• Committee member: Jasna Mrvčić (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: 2022-09-21, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Specifični sojevi Enterococcus vrste primjenjuju se u prehrambenoj industriji u fermentaciji hrane te kao probiotici. No s obzirom da su pojedini sojevi oportunistički patogeni potrebna je detaljna karakterizacija sigurnosti primjene. U ovom radu prioritetno je definirati fenotipske karakteristike Enterococcus faecium, Enterococcus faecalis i Enterococcus durans sojeva, povezane sa sigurnošću primjene kao starter ili probiotičkih kultura, koji su prethodno izolirani iz mikrobioma autohtonih hrvatskih sireva. Definirana je hemolitička i želatinozna aktivnost, mogućnost formiranja biofilma, prisutnost gena za enterocin A i enterocin B. S tehnološkog aspekta proveden je i postupak liofilizacije čistih kultura Enterococcus sojeva, kako bi se odredio postotak preživljavanja tijekom pripreme liofilizata. Ustanovljeno je da niti jedan od analiziranih sojeva ne iskazuje hemolitičku ili želatinoznu aktivnost. 55 % sojeva ima sposobnost formiranja biofilma što uz sintezu enterocina A i/ili enterocina B ukazuje kako pojedini sojevi imaju potencijalnu primjenu kao starter kulture. Svi analizirani sojevi dobro preživljavaju liofilizaciju u obranom mlijeku, osim Enterococcus faecium /durans ZG4-24.

Abstract (english)

Specific strains of Enterococcus species are used in the food industry in food fermentation and as probiotics. However, given that certain strains are opportunistic pathogens, a detailed characterization of the safety of application is required. In this paper, it is priority to define the phenotypic characteristics of Enterococcus faecium, Enterococcus faecalis and Enterococcus durans strains, related to safety of use as starter or probiotic cultures, which were previously isolated from the microbiome of autochthonous Croatian cheeses. Hemolytic and gelatinous activity, the possibility of biofilm formation, the presence of genes for enterocin A and enterocin B were defined. From a technological point of view, the lyophilization procedure of pure cultures of Enterococcus strains was carried out, in order to determine the percentage of survival during the preparation of the lyophilizate. It was found that none of the analyzed strains exhibits hemolytic or gelatinous activity. 55 % of the strains have the ability to form biofilms, which, along with the synthesis of enterocin A and/or enterocin B, indicates that certain strains have a potential application as starter cultures. All analyzed strains survive lyophilization in skimmed milk well, except for Enterococcus faecium/durans ZG4-24.

• Keywords: Enterococcus; probiotičke starter kulture; bakteriocini; biofilm
• Keywords (english): Enterococcus; probiotic starter cultures; bacteriocins; biofilm
• Language: croatian
• URN:NBN: urn:nbn:hr:159:070163
• 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: Open access
• Created on: 2023-02-13 13:34:21