Ispitivanje probiotičkih i imunomodularnih karakteristika prirodnih izolata enterokoka u modelima in vitro i in vivo
Examination of probiotic and immunomodulatory characteristics of natural isolates of enterococci on in vitro and in vivo models
Author
Popović, Nikola D.
Mentor
Veljović, KatarinaCommittee members
Jovčić, Branko
Đokić, Jelena

Veljović, Katarina
Jovčić, Branko

Metadata
Show full item recordAbstract
Enterokoke pripadaju grupi mleĉnokiselinskih bakterija koje su široko rasprostranjene
u prirodi. Predominantno se nalaze u gastrointestinalnom traktu životinja, od insekata do
ĉoveka i preko fecesa se oslobaĊaju u spoljašnju sredinu, nakon ĉega naseljavaju razliĉita
staništa. Imaju kontroverzni status zbog uloge u bolniĉkim infekcijama i širenja gena
odgovornih za rezistenciju na antibiotike. S druge strane, neki sojevi se koriste kao probiotici
za životinje i ĉoveka, kao i starter kulture u mlekarskoj industriji. Da bi se enterokoke
koristile kao probiotici neophodno je da budu bezbedne za korišćenje, da nemaju hemolitiĉku
i želatinoznu aktivnost i da nisu otporne na antibiotike. Enterokoke sintetišu antimikrobne
proteine, bakteriocine, i na taj naĉin regulišu brojnost drugih bakterija i modulišu odgovor
domaćina na infekciju. One mogu da sintetišu i biomolekule koji interaguju sa ćelijama
domaćina i na taj naĉin mogu da menjaju razliĉite signalne puteve unutar ćelija domaćina.
Biomol...ekuli sintetisani od strane probiotiĉkih enterokoka nazivaju se postbiotici. Primena
postbiotika predstavlja bezbednu alternativu korišćenja enterokoka u biomedicini.
Ova doktorska disertacija imala ja za cilj da ispita probiotiĉka i imunomodulatorna
svojstva prirodnih sojeva enterokoka izolovanih iz fermentisanih mleĉnih proizvoda sa
podruĉja Zapadnog Balkana. Definisana su tri cilja: 1. da se pronaĊu sojevi bezbedni za
korišćenje u biomedicini; 2. da se ispitaju probiotiĉke karakteristike tih sojeva u modelima in
vitro; i 3. da se ispita imunomodulatorni efekat odabranog soja u modelima in vitro i in vivo.
U cilju ispitivanja bezbedne upotrebe enterokoka kao probiotika testirano je ukupno 75
sojeva iz fermentisanih mleĉnih proizvoda koje pripadaju vrstama: Enterococcus durans (50
sojeva), Enterococcus faecium (15 sojeva), Enterococcus faecalis (6 sojeva), Enterococcus
italicus (3 soja) i Enterococcus hirae (1 soj). Hemolitiĉku aktivnost pokazalo je 18,7%
(14/75), dok je želatinaznu aktivnost imalo 6,7% (5/75) testiranih sojeva. Na osnovu rezultata
testa mikrodilucije pokazana je visoka uĉestalost rezistencije na ciprofloksacin 48,2%
(27/56), dok su u manjoj meri testirani sojevi rezistentni na gentamicin 10,7% (6/56). Na
osnovu rezultata sposobnosti formiranja biofilma u primenjenim uslovima, devet sojeva nema
sposobnost formiranja biofilma, 11 sojeva ima mogućnost formiranja slabog biofilma,
BGGO9-28 ima sposobnost formiranja jakog biofilma, dok sojevi BGTRK4-42 i BGZLM1-5
pokazuju veoma jaku sposobnost formiranja...
are predominantly found in the gastrointestinal tract of animals, from insects to humans
and through faeces they are released into the environment, where they colonize different
habitats. They have a controversial status according to the role as causative agents of hospital
infections and the spread of genetic determinants of antibiotic resistance. In contrary, some
strains have been used used as probiotics for animals and humans, as well as a starter cultures
in the dairy industry. In order to use enterococci as probiotics, it is necessary to determine
their safety, i.e. absence of hemolytic and gelatinase activity and susceptiblity to clinicaly
relevant antibiotics. Enterococci synthesize antimicrobial proteins, bacteriocins, by which
way they regulate the number of other bacteria and modulate the host response to the
infection. They can also synthesize biomolecules that interact with the host cells, and change
the different signalling pathways within host cells. Biomolecules synthes...ized by probiotic
enterococci are called postbiotics. The use of postbiotic represents a safety alternative to the
enterococci application in biomedicine.
The aim of this dissertation was examination of probiotic and immunomodulatory
characteristics of enterococci isolated from fermented dairy products from the Western
Balkans countries. Three objectives were defined: 1. to find strains safe for use in
biomedicine; 2. to examine the probiotic characteristics on in vitro models, and 3. to examine
the immunomodulatory effect of the selected strain on in vitro and in vivo models. In order to
analyse the safe use of enterococci as a probiotics, a total of 75 isolates from fermented dairy
products were tested: Enterococcus durans (50 isolates), En. faecium (15 isolates), En.
faecalis (6 isolates), En. italicus (3 isolates) and En. hirae (1 isolate). 18.7% (14/75) strains
showed hemolytic activity, while 6.7% (5/75) had gelatinase activity. Based on the results of
the microdilution test, 48.2% (27/56) of strains were ciprofloxacin resistance, while 10.7%
(6/56) strains were resistant to gentamicin. According to the analysis of selected enterococci
genomes, high incidence of adhesin encoding genes could be noticed. It was found that
30.4% of strains have three genes encoding different virulence factors, 21.7% of strains
having two or four genes, 17.4% having five genes, and 4.3% of studied enterococci
containing 6 or 7 genes which encode virulence factors, while the presence or absence of
gene within the fsr operon varies from the analyzed strains...
Faculty:
Универзитет у Београду, Биолошки факултетDate:
05-07-2019Projects:
- Rare Diseases:Molecular Pathophysiology, Diagnostic and Therapeutic Modalities and Social, Ethical and Legal Aspects (RS-41004)
- Genes and molecular mechanisms promoting probiotic activity of lactic acid bacteria from Western Balkan (RS-173019)