Induciranje biosinteze bakteriocina kod različitih probiotičkih sojeva nakon uzgoja u mješovitoj kulturi s Lactococcus lactis supsp. lactis LMG 9450

master's thesis

• Title (english): Induction of the bacteriocin biosynthesis by different probiotic strains after cocultivation with Lactococcus lactis supsp. lactis LMG 9450
• Author: Martina Švađumović
• Mentor: Jasna Beganović (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: 2010-07, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Biosinteza bakteriocina pomocu probiotičkih sojeva doprinosi kolonizaciji epitelnih stanica domaćina, njegovoj zaštiti od patogena, te uspostavljanju probiotičkog soja u kompetitivnom okolišu prisutnom u gastrointestinalnom traktu domaćina. Stoga je, u ovom radu ispitivano antimikrobno djelovanje probiotičkih sojeva Lactobacillus helveticus M92, Lactobacillus plantarum L4, Enterococcus faecium L3, s posebnim osvrtom na biosintezu bakteriocina. Antibakterijska aktivnost navedenih probiotičkih sojeva ispitana je prema različitim test mikroorganizmima, učestalim kontaminantima hrane, te uzročnicima crijevnih infekcija, ali i prema predstavnicima istih i srodnih bakterijskih vrsta. Prisutnost i združeni uzgoj bakteriocin-osjetljivog mikroorganizma i producenta bakteriocina potiče biosintezu bakteriocina. Stoga je istražena mogućnost induciranja biosinteze bakteriocina pomoću stanica bakterije Lactococcus lactis subsp. lactis LMG 9450. Istražena je i prisutnost nekoliko gena koji kodiraju za različite bakteriocine pomoću lančane reakcije polimerazom uz primjenu specifičnih početnica. Svi probiotički sojevi su pokazali snažnu antimikrobno djelovanje koja je važno funkcionalno svojstvo i jedan od ključnih mehanizama kompetitivne ekskluzije koja probiotičkim sojevima omogućuje selektivnu prednost pred patogenim mikroorganizmima u specifičnim uvjetima gastrointestinalnog trakta domaćina. Dobiveni rezultati ukazuju na mogućnost indukcije bakteriocinske aktivnosti ispitivanih probiotičkih sojeva živim stanicama Lact. lactis subsp. lactis LMG 9450.

Abstract (english)

Bacteriocin biosynthesis by probiotic strains can contribute to the colonisation resistance of the host, its protection against gastrointestinal pathogens and facilitate the establishment of a probiotic strain in the competitive environment of the gut. Hence, the objective of this thesis was to investigate an antimicrobial activity of probiotic strains, Lactobacillus helveticus M92, Lactobacillus plantarum L4, Enterococcus faecium L3 with the special focus on bacteriocinogenic activity. Their antimicrobial activity was tested towards different test microorganisms, potential food contaminants or causative agents of gut infections, moreover towards representatives of the same or related bacterial species. Presence and close contact of competing microorganism has been reported to be an environmental factor affecting bacteriocin biosynthesis by LAB. Hence, in order to induce bacteriocin production, probiotic cells were cocultivated with Lact. lactis subsp. lactis LMG 9450 cells. The detection of the different genes coding for bacteriocin was investigated by PCR amplification of the specific primers. All probiotic strains have shown strong antimicrobial activity which is an important functional characteristic of probiotic strains and one of crucial mechanisms of competitive exclusion which provides probiotic strains selective advantage against pathogen microorganisms in a specific microenvironment or in gastrointestinal tract of the host. The obtained results propose that living cells of Lact. lactis subsp. lactis LMG 9450 could induce bacteriocin production by examined probiotic strains.

• Keywords: antimikrobno djelovanje; bakteriocini; induciranje biosinteze bakteriocina; probiotici
• Keywords (english): antimicrobial activity; bacteriocins; induction of bacteriocin biosynthesis; probiotics
• Language: croatian
• URN:NBN: urn:nbn:hr:159:314425
• Study programme: Title: Biotechnology; specializations in: Biochemical Engineering; Course: Biochemical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer biotehnologije; smjer biokemijsko inženjerstvo (diplomirani inženjer biotehnologije; smjer biokemijsko inženjerstvo)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-08-28 08:45:32