Funkcionalnost autohtonih starter kultura Enterococcus faecium A7 i Lactobacillus fermentum A8

master's thesis

• Title (english): Functionality of autochthonous starter cultures Enterococcus faecium A7 and Lactobacillus fermentum A8
• Author: Ivana Canjer
• 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: 2013-07-15, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Cilj ovog rada bio je karakterizacija autohtonih bakterijskih sojeva Enterococcus faecium A7 i Lactobacillus fermentum A8, izoliranih iz hrvatskog tradcionalnog svježeg sira, kao potencijalnih probiotika. Bakterijski sojevi Ec. faecium A7 i Lb. fermentum A8 preživljavaju visoke koncentracije vodikovih iona (pH 2,0) i otporni su na djelovanje pepsina u simuliranom sekretu želuca. Neosjetljivi su prema djelovanju enzima gušterače i pokazuju otpornost prema djelovanju žučnih soli (3,0 mg/ml). Bakterijski soj Ec. faecium A7 je osjetljiv na sve ispitane antibiotike (bacitracin, benzilpenicilin, eritromicin, kloramfenikol, rifampicin, streptomicin, tetraciklin, vankomicin), a soj Lb. fermentum A8 je rezistentan samo na vankomicin. Oba ispitana bakterijska soja pokazuju visok postotak autoagreagacije te mogućnost koagregacije s drugim bakterijama mliječne kiseline dok je soj Lb. fermentum A8 koagregirao i s ispitanim test-mikroorganizmima. Visoki postotak adhezije stanica na ksilen upućuje na njihovu hidrofobnost, a afinitet svih ispitivanih sojeva za kloroform, na elektrondonorska svojstva površine bakterijskih stanica. Svi sojevi pokazuju slabu aktivnost hidrolaze žučnih soli jer su dekonjugirali cca 12% taurokolata dodanog u hranjivu podlogu. Ispitivanjem asimilacije različitih prebiotičkih supstrata, tijekom uzgoja u hranjivim podlogama s prebioticima laktulozom i manitolom, ustanovljen je najveći rast ispitivanih sojeva, kao i najveća promjena pH vrijednosti uslijed nastajanja mliječne kiseline.

Abstract (english)

The aim of this work was to characterize autochthonous strains Enterococcus faecium A7 and Lactobacillus fermentum A8, isolated from Croatian traditional fresh cheese, as potential probiotics. Ec. faecium A7 and Lb. fermentum A8 strains survive high concentration of hydrogen ions (pH 2.0) and are resistant to pepsin in the simulated gastric juice. They are insensitive to the activity of pancreatic enzymes and are resistant to bile salts (3.0 mg/ml). Bacterial strain Ec. faecium A7 is sensitive to all tested antibiotics (bacitracin, benzylpenicillin, erythromycin, chloramphenicol, rifampin, streptomycin, tetracycline, vancomycin) and strain Lb. fermentum A8 is resistant only to vancomycin. Both tested bacterial strains show high percentage of autoaggregation and the ability of coaggregation with other lactic acid bacteria while strain Lb. fermentum A8 coaggregated also with examined test-microorganisms. A high percentage of cell adhesion on ksilen points to their hydrophobicity, and high affinity to the chloroform points on electron-donor properties of the surface of bacterial cells. All strains showed weak bile salt hydrolase activity since they have deconjugate only cca 12% of taurocolate in the media. Within the examination of assimilation of various prebiotic substrates, the biggest growth of chosen strains as well as the biggest change of pH value due to production of lactic acid was found in media where lactulose and mannitol were used as prebiotics.

• Keywords: autohtone starter kulture; probiotici; prebiotici; agregacija; MATS; hidrolaze žučnih soli
• Keywords (english): autochthonous starter cultures; probiotics; probiotics; aggregation; MATS; bile salt hydrolase
• Language: croatian
• URN:NBN: urn:nbn:hr:159:794302
• Study programme: Title: Nutrition; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra nutricionizma (magistar/magistra nutricionizma)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-04 12:56:09