| Summary: | Thesis (MSc)--University of Stellenbosch, 2007. === ENGLISH ABSTRACT: The tolerance of Enterococcus mundtii ST4SA to stressful gastro-intestinal conditions in
humans and animals is vital to its success as a probiotic. The need for new effective
probiotics with stronger inhibitory (bacteriocin) activity has arisen due to the increasing
number of antibiotic resistant pathogens. Enterococci are used in the fermentation of
sausages and olives, cheese making and as probiotics. Their role as opportunistic
pathogens in humans makes them a controversial probiotic (Moreno et al., 2005).
Enterococci occur naturally in the gastro-intestinal tract which renders them intrinsic acid
and bile resistance characteristics. E. mundtii ST4SA produces a 3950 Da broad-spectrum
antibacterial peptide active against Gram-positive and Gram-negative bacteria, and
viruses. The bacteria include Enterococcus faecalis, Streptococcus spp., Pseudomonas
aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae and Staphylococcus
aureus. E. mundtii ST4SA inactivates the herpes simplex viruses HSV-1 (strain F) and
HSV-2 (strain G), a measles virus (strain MV/BRAZIL/001/91, an attenuated strain of
MV), and a polio virus (PV3, strain Sabin).
This study focuses on the genetic stability of E. mundtii ST4SA genes when exposed to
stress factors in the human and animal gastrointestinal tract. Based on results obtained by
real-time PCR, the expression of genes encoding bacST4SA, RecA, GroES and 23S
rRNA by E. mundtii ST4SA were not affected when the cells were exposed to acid, bile
and pancreatic juice. This suggests that these genes of E. mundtii ST4SA will remain
stable in the intestine. This could indicate that other genes of E. mundtii ST4SA could
remain stable in the host. Further studies on the stability of genes encoding antibiotic
resistance and virulence factors should be conducted to determine their stability and
expression in the host in stress conditions. Concluded from this study, E. mundtii ST4SA
is an excellent probiotic strain. === AFRIKAANSE OPSOMMING: Enterococcus mundtii ST4SA se weerstandsvermoë teen stresvolle gastrointestinale
kondisies is essensieel vir die sukses van hierdie organisme as ‘n probiotikum. Die
aanvraag vir nuwe, meer effektiewe probiotika met sterker inhibitoriese (bakteriosien)
aktiwiteit is as gevolg van die toename in antibiotikum weerstandbiedende patogene.
Enterococci word algemeen gebruik as probiotika, sowel as in die fermentasie van worse,
olywe en kaas. Hulle rol as oppertunistiese patogene in mense veroorsaak kontroversie as
gevolg van hul toenemende gebruik as probiotika. Enterococci is deel van die natuurlike
mikroflora in die gastrointestinale weg van mense en diere. Dit verleen aan hierdie
spesies ‘n natuurlike weerstandsvermoë teen maagsure, galsoute en pankreatiese
afskeidings. E. mundtii ST4SA produseer ‘n 3950 Da wye spektrum anti-bakteriese
peptied, aktief teen Gram positiewe en Gram negatiewe bakterieë sowel as virusse.
Hierdie bakterieë sluit Enterococcus faecalis, Streptococcus spp., Pseudomonas
aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae en Staphylococcus
aureus in. E. mundtii ST4SA inaktiveer die herpes simpleks virus HSV-1 en HSV-2, ‘n
masels virus (MV/BRAZIL/001/91), en ‘n polio virus (PV3, stam Sabin).
Hierdie studie fokus op die genetiese stabiliteit van E. mundtii ST4SA gene, wanneer
hulle blootgestel word aan stress faktore in die mens en dier gastrointestinale weg.
“Intydse” PKR data gebasseer op die uitdrukking van die bacST4SA, RecA, GroES en
23S rRNA gene in stresvolle kondisies dui aan dat E. mundtii ST4SA nie geaffekteer
word wanneer die sel blootgestel word aan suur, gal en pankreatiese vloeistowwe nie.
Hierdie resultate dui aan dat hierdie gene van E. mundtii ST4SA stabiel sal bly in die
intestinale weg van die mens en dier. Dit kan aandui dat ander gene van E. mundtii
ST4SA soos die wat kodeer vir virulensie faktore en antibiotikum se weerstandsvermoë
stabiel mag bly in die gasheer. Verdere studies wat fokus op die stabiliteit van gene wat
kodeer vir antibiotikum weerstandbiedendheid en virulensie faktore moet uitgevoer word
om hulle stabiliteit en uitdrukking in die gasheer te bepaal. Bevindings van hierdie studie
dui aan dat E. mundtii ST4SA goeie potensiaal het as ‘n probiotikum.
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