Antibakterijsko djelovanje probiotičkih sojeva iz rodova Bifidobacterium i Lactobacillus

undergraduate thesis

• Title (english): Antibacterial activity of probiotic strains Bifidobacterium and Lactobacillus
• Author: Josipa Jusup
• Mentor: Jasna Novak (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: 2014-07-10, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Antibakterijsko djelovanje probiotičkih bakterija mliječne kiseline je rezultat višestrukih čimbenika, snižavanja pH vrijednosti, sinteze mliječne kiseline i drugih antibakterijskih sastojaka, poput bakteriocina. Upravo je cilj ovog rada ispitati antibakterijsko djelovanje tri različita soja probiotičkih bakterija, Lactobacillus rhamnosus GG, Lactobacillus reuteri DSM 17938 i Bifidobacterium longum BB536, koji su prisutni na tržištu kao liofilizirani probiotički pripravci, prema enteropatogenim bakterijama Escherichia coli 3014 i Salmonella enterica serovar Typhimurium FP1, koje se prenose hranom. Probiotičke bakterije Lactobacillus rhamnosus GG, Lactobacillus reuteri DSM 17938 i Bifidobacterium longum BB536 iskazuju antibakterijsko djelovanje, što je utvrđeno na temelju rezultata inhibicije rasta E. coli 3014 i S. enterica serovar Typhimurium FP1, što je od značaja za njihov bioterapijski učinak prilikom in vivo primjene u suzbijanju infekcija uzrokovanih navedenim bakterijama kod domaćina. S ciljem karakterizacije antagonističkog međudjelovanja probiotičkih sojeva i bakterija mliječne kiseline iz srodnih rodova, ispitano je i inhibicijsko djelovanje navedenih probiotičkih sojeva prema bakterijama Lb. plantarum LMG 9206, Ec. faecium ATCC 9430 i Lc. lactis subsp. lactis LMG 9450. Iz rezultata proizlazi da probiotičke bakterije inhibiraju rast triju bakterija mliječne kiseline, koje je u usporedbi s inhibicijskim djelovanjem prema test mikroorganizmima slabijeg inteziteta, no kako se radi o inhibiciji sojeva iz bliskih bakterijskih rodova, moguće je da antibakterijski učinak proizlazi iz sinergističkog djelovanja mliječne kiseline i drugih antimikrobnih sastojaka poput antimikrobnih peptida-bakteriocina. Turbidimetrijskom metodom je dodatno potvrđeno inhibicijsko djelovanje supernatanata kultura pojedine probiotičke bakterije prema navedenim enteropatogenim sojevima, čiji je antibakterijski učinak, prema rezultatima, učinkovit i u razrijeđenom obliku, pa se može ciljano primjeniti u prehrambenom matriksu ili gastrointestinalnom traktu domaćina gdje je potrebno antimikrobno djelovanje ispitivanog probiotičkog soja.

Abstract (english)

The mechanisms underlying the antibacterial activity of probiotic bacteria appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins. The aim of this work is to test the antibacterial activity of three different strains of probiotic bacteria, Lactobacillus rhamnosus GG, Lactobacillus reuteri DSM 17938 and Bifidobacterium longum BB536 available on the market, as a freeze-dried probiotic preparations, against entheropathogenic bacteria Escherichia coli 3014 and Salmonella enterica serovar Typhimurium FP1, that are foodborne pathogens. Probiotic bacteria Lactobacillus rhamnosus GG, Lactobacillus reuteri DSM 17938 and Bifidobacterium longum BB536 show antibacterial activity which was confirmed based on results of growth inhibition of E. coli 3014 and S. enterica serovar Typhimurium FP1. This is significant for the potential biotherapeutic effect during their in vivo application in preventing infections caused by given bacteria in the host. Inhibitory effect of given probiotic strains against bacteria Lb. plantarum LMG 9206, Ec. faecium ATCC 9430 and Lc. lactis subsp. lactis LMG 9450 was also tested to characterise anthagonistic interactions between probiotic strains and lactic acid bacteria belonging to closley related taxa. The results have shown that probiotic bacteria inhibited the growth of three lactic acid bacteria which was of lower intensity compared to inhibitory effect towards the test microorganisms, but because it is the inhibition of bacterial strains from closley related taxa, it is possible that the antibacterial effect arises from the synergistic effect of lactic acid and other antimicrobial compounds such as antimicrobial peptide-bacteriocins. Inhibitory activity against these entheropathogenic strains has been further confirmed by using turbidimetric method, wherein the inhibitory effect of cultures supernatants was so effective that it could be applied in diluted form, indicating their target application in the food matrix or the gastrointestinal tract of the host where their antimicrobial activity is beneficial.

• Keywords: probiotici; antibakterijsko djelovanje; Lactobacillus rhamnosus; Lactobacillus reuteri; Bifidobacterium longum
• Keywords (english): probiotic; antibacterial activity; Lactobacillus rhamnosus; Lactobacillus reuteri; Bifidobacterium longum
• Language: croatian
• URN:NBN: urn:nbn:hr:159:172839
• Study programme: Title: Biotechnology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-04-26 12:23:04