Browsing by Author "Botes, Marelize"
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- ItemAntimikrobiese nanovesels vir waterbehandeling : poli(vinielalkohol)- en poli(akrielonitriel)- nanovesels met silwer-nanopartikels(LitNet, 2012) Du Plessis, Danielle; Botes, Marelize; Dicks, Leon Milner Theodore, 1961-; Cloete, Thomas EugeneDaar moet verbeter word op bestaande watersuiweringsmetodes ten einde mikrobiologies veilige en bekostigbare drinkwater te verskaf. Nanovesels word reeds gebruik in waterfiltrasiesisteme en nanofiltrasie mag selfs as ’n alternatief vir biosiede gebruik word. Verskeie variasies van nanovesels met biosiede is in die onlangse literatuur omskryf. Omdat nanovesels met antimikrobiese aktiwiteit ’n relatief nuwe studieveld is, is nog weinig studies gewy aan die uiteensetting van praktiese standaardmetodes vir antimikrobiese-aktiwiteit-bepaling. Die aktiwiteit van antimikrobiese vesels word oor die algemeen met plaattellings van kolonievormende eenhede (KVE) bepaal. Hierdie metode bepaal ’n afname in die getal kweekbare patogeniese selle teenwoordig. Die hoofdoel van hierdie studie was om ’n vinnige, maklik uitvoerbare en akkurate toets te ontwikkel om die aktiwiteit van antimikrobiese nanovesels te bepaal.
- ItemThe formulation of synthetic domestic wastewater sludge medium to study anaerobic biological treatment of acid mine drainage in the laboratory(South African Water Research Commission, 2016-04) Van den Berg, M. Francis; Botes, Marelize; Cloete, T. EugeneRequirements for successful biological treatment of acid mine drainage (AMD) rely on the reduction of sulphates by microorganisms using a suitable organic carbon source. Various carbon sources, such as domestic wastewater sludge, have previously been used in the semi-passive biological treatment of AMD. Domestic wastewater sludge is however highly variable in its composition, making laboratory experimentation difficult. Synthetic medium was therefore formulated based on the chemical oxygen demand (COD) and the biological degradable organic matter (BOD) of domestic wastewater sludge. Four synthetic media compositions were formulated consisting of different ratios of meat extract, vegetable extract, sodium chloride, potassium phosphate, urea, ammonium chloride, iron sulphate, magnesium sulphate and glucose. The media composition with BOD and COD measurements closest to that of anaerobic domestic wastewater sludge was selected for further studies. The combination of AMD to synthetic wastewater sludge in 3 ratios was determined for COD and sulphate reduction in bioreactors over a period of 90 d. The highest reduction of 86.76% in COD and 99.22% in sulphate content were obtained in a 1:1 AMD: synthetic domestic wastewater sludge (SDWWS) ratio that calculated to a COD/sulphate ratio of 3.
- ItemLactobacillus equigenerosi strain Le1 invades equine epithelial cells(American Society for Microbiology, 2012) Botha, Marlie; Botes, Marelize; Loos, Ben; Smith, Carine; Dicks, Leon Milner Theodore, 1961-Lactobacillus equigenerosi strain Le1, a natural inhabitant of the equine gastrointestinal tract, survived pH 3.0 and incubation in the presence of 1.5% (wt/vol) bile salts for at least 2 h. Strain Le1 showed 8% cell surface hydrophobicity, 60% auto-aggregation, and 47% coaggregation with Clostridium difficile C6. Only 1% of the cells adhered to viable buccal epithelial cells and invaded the cells within 20 min after contact. Preincubation of strain Le1 in a buffer containing pronase prevented adhesion to viable epithelial cells. Preincubation in a pepsin buffer delayed invasion from 20 min to 1 h. Strain Le1 did not adhere to nonviable epithelial cells. Administration of L. equigenerosi Le1 (1x10 9 CFU per 50 kg body weight) to healthy horses did not increase white blood cell numbers. Differential white blood cell counts and aspartate aminotransferase levels remained constant. Glucose, lactate, cholesterol, and urea levels remained constant during administration with L. equigenerosi Le1 but decreased during the week after administration.
- ItemSurvival of probiotic lactic acid bacteria in the intestinal tract, their adhesion to epithelial cells and their ability to compete with pathogenic microorganisms(Stellenbosch : Stellenbosch University, 2008-03) Botes, Marelize; Dicks, Leon Milner Theodore; Stellenbosch University. Faculty of Science. Dept. of Microbiology.ENGLISH ABSTRACT: Research on probiotics has increased over the past years, which led to commercialization of a number of probiotic supplements and functional foods. In vitro assays such as tolerance to acid and bile, adhesion to mucus and epithelial cells, antimicrobial activity and antibiotic resistance tests are performed to screen lactic acid bacteria for probiotic properties. Enterococcus mundtii ST4SA produces an antimicrobial peptide (peptide ST4SA) with activity against Gram-positive and Gram-negative bacteria. Lactobacillus plantarum 423 produces plantaricin 423, a typical class II bacteriocin, active against a number of Gram-positive bacteria. A gastro-intestinal model (GIM) simulating the gastro-intestinal tract (GIT) of infants, was developed to study the survival of E. mundtii ST4SA and L. plantarum 423 and evaluate them as possible probiotics. Growth of the two strains in the GIM was compared to the growth of commercially available probiotics. Infant milk formulations were used as growth medium. Changes in pH, the addition of bile salt and pancreatic juice, and intestinal flow rates were controlled by peristaltic pumps linked to a computer with specifically designed software. Strain ST4SA was sensitive to low pH and high concentrations of bile salts. Growth of strain ST4SA was repressed in the first part of the GIM, however, the cells recovered in the ileum. Strain 423 was also sensitive to acidic conditions. However, the cells withstood the presence of bile and pancreatin in the first part of the GIT. Neither of the two strains displayed bile salt hydrolase (BSH) activity. Both strains were resistant to amoxicillin, ampicillin, chloramphenicol, cefadroxil, roxithromycin, meloxicam, doxycycline, erythromycin, novobiocin, rifampicin, tetracyclin, bacitracin, oflaxacin and cephazolin, anti-inflammatory drugs Na+- diklofenak and ibuprofen, and painkillers codeine terprim hydrate aminobenzoic acid, metamizole aspirin and paracetamol. Strain 423 was resistant to ciprofloxacin. Genes encoding cytolysin, non-cytolysin β-hemolysin and cell aggregation substances were detected on the genome of strain ST4SA but they were not expressed. L. plantarum 423 does not contain genes encoding gelatinase, cell aggregation, enterococcus surface protein, hemolysin, non-cytolysin β- hemolysin and enterococcus endocarditis antigen. Both strains inhibited the growth of Listeria monocytogenes ScottA in the GIM. Survival of the strains improved when used in combination and compared well with the survival of commercially available probiotics. Adhesion to epithelial cells is an important prerequisite for bacterial colonization in the GIT. The adhesion of E. mundtii ST4SA and L. plantarum 423 was studied using Caco-2 (human colon carcinoma epithelial) cells. Both strains revealed good adhesion compared to other probiotic strains. No correlation was found between hydrophobicity, auto-aggregation and adhesion to Caco-2 cells. Antibiotics and anti-inflammatory medicaments had a negative effect on adhesion. Different combinations of proteins were involved in the adhesion of E. mundtii ST4SA and L. plantarum 423 to Caco-2 cells. E. mundtii ST4SA, L. plantarum 423 and L. monocytogenes ScottA were stained with fluorescent dyes to visualize adhesion to Caco-2 cells. Adhesion of L. monocytogenes ScottA to Caco-2 cells was not reduced in the presence of strains ST4SA and 423. Cell-free culture supernatants of both strains inhibited the invasion of L. monocytogenes ScottA. The cell structure of Caco-2 cells changed in the presence of L. monocytogenes ScottA. Strains ST4SA and 423 protected Caco-2 cells from deforming.