Thesis (M.Sc. (Microbiology)) --University of Limpopo, 2015 / Five plant species: Ziziphus mucronata, Senna italica, Lantana camara, Ricinus communis and Lippia javanica, were selected for this study based on their use in traditional medicine. In preliminary screening, crude extracts were prepared using hexane, dichloromethane (dcm), acetone and methanol. Phytochemical profiles on Thin Layer Chromatography plates of the extracts were obtained by developing the plates in mobile phases of varying polarity. Tests for compounds such as tannins, flavonoids, alkaloids, phlobatannins, terpenes, steroids, cardiac glycosides and saponins were carried out. Antibacterial activity of the extracts was carried out using microdilution assay for Minimum Inhibitory Concentration and bioautography against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis. Antioxidant activity of the extracts was performed using the 2, 2, diphenyl-1-picrylhydrazyl (DPPH) assay. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay and Phagoburst test were used to investigate the toxic effects and anti-inflammatory activity of the extracts on mouse Raw 264.7 macrophage cells, respectively. The presence of phytochemicals was observed on the chromatograms after the plates were sprayed with vanillin sulphuric acid reagent. The dcm extracts of the plants showed antibacterial activity against the selected bacterial species on the bioautograms. Senna italica and Z. mucronata showed the most activity bands on the bioautograms. Lippia javanica had the lowest MIC average of 0.56 mg/ml. Antioxidant activity was observed in the extracts of L. javanica and R. communis. The extracts promoted proliferation of the mouse macrophage cells Raw 264.7 at concentrations ranging from 0.31 mg/ml and 0.08 mg/ml. Senna italica leaves were selected for isolation of antibacterial compounds. The isolated compound was analysed on 1H and 13C nuclear magnetic resonance (NMR) and Mass Spectrometry (MS) for structural analysis. The structure could not be elucidated due to impurities in the compound but the tentative structure is a branched chain alkane with at least one ether linkage per repeating unit. Therefore the study shows that there are plant components with biological activities against wound infecting bacteria and a single lead compound was identified. / the National Research Foundation

In many countries, the authorities face extreme difficulties in monitoring and ensuring that food sold on the street is safe, that is, fit for human consumption. This is particularly the case in urban areas, where people buy food on the street because it is readily available and relatively inexpensive. The objective of this study was to determine the food safety knowledge and microbial hazard awareness of street food consumers, and to assess the bacteriological quality of selected ready-to-eat foods sold by street vendors in the Johannesburg municipality. A cross-sectional survey study was conducted and a total of 402 respondents who buy and consume street-vended foods were randomly selected at various street food vending locations. A total of 315 various street-vended samples were purchased from randomly selected street food vendors at different vending locations in Johannesburg metropolis, in order to investigate the bacteriological quality of street-vended foods. Results of the bacteriological analysis revealed that total aerobic counts ranged from 0.3*102 - 0.4*105 cfu/g in cereals and grain-based foods; 0.4*102 - 0.5*105 cfu/g in meat-, dairy- and fish-based foods and 0.7*102 - 0.9*104 cfu/g in fruit- and vegetable-based foods. None of the food samples tested positive for Salmonella spp and Staphylococcus aureus. Results of the survey showed that the majority of respondents were black males younger than 35 years. Individuals of different gender, race, level of education and monthly income groups significantly (p<0.05) differed in their responses regarding the frequency of purchasing and confidence in the safety of street-vended food. Better taste followed closely by affordability and accessibility were the most cited reasons for purchasing street-vended food / Life and Consumer Sciences / M. Sc. (Life Sciences)