Antimikrobno djelovanje Lactobacillus fermentum A8 i Enterococcus faecium A7

master's thesis

• Title (english): Antimicrobial activity of Lactobacillus fermentum A8 and Enterococcus faecium A7
• Author: Marko Šulj
• 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: 2010-10, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

U ovom radu ispitana je antimikrobna aktivnost Lactobacillus fermentum A8 i Enterococcus faecium A7, jedno od najvažnijih funkcionalnih svojstava probiotičkih bakterija. Antimikrobna aktivnost supernatanata kultura ispitana je prije i nakon podešavanja pH vrijednosti na 6,5, kako bi se uklonio inhibicijski učinak mliječne kiseline, te ispitala mogućnost proizvodnje drugih antimikrobnih metabolita, s posebnim naglaskom na biosintezu bakteriocina. Biosinteza bakteriocina pomoću probiotičkih sojeva doprinosi kolonizaciji intestinalnih epitelnih stanica domaćina i njegovoj zaštiti od patogena u kompetitivnom okolišu gastrointestinalnog trakta. Antibakterijska aktivnost navedenih probiotičkih sojeva ispitana je turbidimetrijskom metodom i metodama difuzije u agar prema potencijalnim patogenim mikroorganizmima, kao i prema predstavnicima istih i srodnih bakterijskih vrsta. Prisutnost i združeni uzgoj bakteriocin-osjetljivog mikroorganizma i mikroorganizma producenta bakteriocina potiče biosintezu bakteriocina. Istražena je i mogućnost induciranja biosinteze bakteriocina živim stanicama bakterije Lactococcus lactis subsp. lactis LMG 9450, inaktiviranim stanicama liziranim pri 100 °C, kao i supernatantom ove kulture. Ispitana je i prisutnost gena koji kodiraju za bakteriocine pomoću lančane reakcije polimerazom uz primjenu specifičnih početnica. Dobiveni rezultati ukazuju na mogućnost indukcije bakteriocinske aktivnosti odabranih probiotičkih sojeva živim stanicama Lact. lactis subsp. lactis LMG 9450, te na prisutnost gena plnJ koji kodira za bakteriocin kod soja L. fermentum A8.

Abstract (english)

The objective of this thesis was to examine the antimicrobial activity of Lactobacillus fermentum A8 i Enterococcus faecium A7 which is one of the most important functional properties of probiotic bacteria. Antimicrobial activity of the culture supernatants was examined before and after adjusting of pH to 6.5, in order to eliminate the inhibitory effect of lactic acid and investigate the possibility of other antimicrobial metabolites production with special focus on bacteriocin biosynthesis. Bacteriocin biosynthesis by probiotic strains contributes 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. Antimicrobial activity of these probiotic strains was examined, by turbidometric method and agar difussion method, against different test-microorganisms and representatives of the same or related bacterial species. Presence and close contact of competing microorganism is important environmental factor for bacteriocin biosynthesis. The possibility of the induction of bacteriocin biosynthesis in probiotic cells, by cocultivation with Lactoccocus lactis subsp. lactis LMG 9450 cells or Lact. lactis subsp. lactis LMG 9450 cells inactivated by boiling at 100 °C, as well as using culture supernatants of lactic acid bacteria, was investigated. The detection of the different genes coding for bacteriocins was examined by PCR amplification of the specific primers. Results suggest the possibility of induction of bacteriocin biosynthesis by Lact. lactis subsp. lactis LMG 9450 cells and the presence of gene plnJ in L. fermentum A8.

• 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:159:475333
• 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: 2017-08-29 07:51:45