Production and application of probiotic starter cultures of Lactococcus lactis ZG5-9, Lactobacillus pentosus ZG2-25 and Enterococcus faecium ZG1-54

master's thesis

• Title: Proizvodnja i primjena probiotičkih starter kultura Lactococcus lactis ZG5-9, Lactobacillus pentosus ZG2-25 i Enterococcus faecium ZG1-54
• Author: Martina Dolenec
• Mentor: Blaženka Kos (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: 2013-02-26, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Odabrana su tri autohtona soja bakterija mliječne kiseline, Lactococcus lactis ZG5-9, Lactobacillus pentosus ZG2-25 i Enterococcus faecium ZG1-54, izolirana iz tradicionalno proizvedenog svježeg sira s ciljem primjene na kontroliranu proizvodnju svježeg sira koji će po senzorskim svojstvima biti što sličniji tradicionalnom. Prethodno su istraženi sojevi Lactobacillus pentosus ZG2-25 i Lactococcus lactis ZG5-9 u okviru probiotičkog koncepta. Autohtoni izolati bakterija mliječne kiseline osjetljivi su na većinu ispitanih antibiotika, te su stoga sigurni s aspekta kontrole širenja antibiotičke rezistencije. Uočena je rezistencija na vankomicin, no radi se o urođenoj rezistenciji Lactobacillus vrsta, a geni koji su za nju odgovorni se nalaze na genomskoj DNA pa nema opasnosti od transfera gena.Odabrani autohtoni sojevi Lactobacillus pentosus ZG2-25 i Lactococcus lactis ZG5-9 preživljavaju u simuliranim uvjetima gastrointestinalnog sustava, asimiliraju prebiotičke supstrate inulin, manitol, laktulozu i raftilozu. Rast odabranih sojeva, promjena pH i sinteza mliječne kiseline su bili najveći tijekom uzgoja u hranjivim podlogama s manitolom i laktulozom. Bakterije Lactobacillus pentosus ZG2-25 i L. lactis ZG5-9 asimiliraju kolesterol u prisutnosti žučnih soli. Stanice Lactobacillus pentosus ZG2-25 i L. lactis ZG5-9 pokazale su hidrofilna svojstva i afinitet za kloroform, što upućuje na elektron-donorska (lužnata) svojstva površine njihovih stanica. Oba soja, kao i soj Enterococcus faecium ZG1-54 su pokazali vrlo visoko preživljavanje nakon procesa liofilizacije u obranom mlijeku kao lioprotektoru te su upotrijebljeni kao funkcionalne starter kulture za proizvodnju svježeg sira kontroliranom fermentacijom. Sir proizveden s autohtonim probiotičkim sojevima je po senzorskim svojstvima, u odnosu na sir proizveden s komercijalnom starter kulturom, bio puno sličniji siru tradicionalno proizvedenom spontanom fermentacijom.

Abstract (english)

Three autochthonous strains of lactic acid bacteria, Lactococcus lactis ZG5-9, Lactobacillus pentosus ZG2-25 and Enterococcus faecium ZG1-54, isolated from traditionally produced fresh cheese were chosen to be used for the controlled production of fresh cheese with sensory characteristics similar to the traditional cheese. Bacterial strains Lactobacillus pentosus ZG225 and Lactococcus lactis ZG5-9 have been previously investigated strains within the probiotic concept. Those autochthonous lactic acid bacteria isolates are susceptible to most tested antibiotics, and are therefore safe from the standpoint of controlling the spread of antibiotic resistance. There is resistance to vancomycin, but it is the innate resistance of Lactobacillus species, and genes that are responsible are found in genomic DNA without the danger of the gene transfer. Selected autochthonous strains Lactobacillus pentosus ZG2-25 and Lactococcus lactis ZG5-9 survive simulated gastrointestinal conditions, assimilate prebiotic substrates inulin, mannitol, lactulose and raftilozu. Growth of selected strains, changes in pH values and concentrations of lactic acid were highest during cultivation in nutrient media with mannitol and lactulose. Bakterial strains Lactobacillus pentosus ZG2-25 and L. lactis ZG5-9 assimilate cholesterol in the presence of bile salts. The cells of Lactobacillus pentosus ZG2-25 and L. lactis ZG5-9 showed hydrophilic properties and affinity for chloroform, which suggests an electron-donor (alkaline) properties of the surface of their cells. Both strains and strain of Enterococcus faecium ZG1-54 showed a very high survival rate after lyophilization process in skimmed milk as lioprotector and were used as functional starter cultures for fresh cheese production with controlled fermentation. Cheese produced with autochthonous probiotic strains was according to the sensoric properties much similar to the traditionaly produced fresh cheese then the cheese produced with commercial starter cultures.

• Keywords: autohtoni izolati bakterija mliječne kiseline; svježi sir; probiotici; Lactococcus lactis; Lactobacillus pentosus; Enterococcus faecium
• Keywords (english): autochthonous strains of lactic acid bacteria; fresh cheese; probiotics; Lactococcus lactis; Lactobacillus pentosus; Enterococcus faecium
• Language: croatian
• URN:NBN: urn:nbn:hr:159:111791
• Study programme: Title: Molekularna biotehnologija; Study programme type: sveučilišni; Study level: diplomski; 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: Restricted access
• Created on: 2017-05-05 11:45:40