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Growth of Staphylococcus Aureus under stress conditions
Dissertation (MSc (Microbiology))--University of Pretoria, 1984.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2024
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| _version_ | 1867613670666665984 |
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| access_status_str | Open Access |
| author2 | Holzapfel, W.H. |
| author_browse | Holzapfel, W.H. |
| author_facet | Holzapfel, W.H. |
| collection | Thesis |
| dc_rights_str_mv | © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Microbiology))--University of Pretoria, 1984. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/99530 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:50.639Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/99530 Growth of Staphylococcus Aureus under stress conditions Holzapfel, W.H. Winer, Brian Allan Growth Staphylococcus Aureus Stress conditions UCTD Dissertation (MSc (Microbiology))--University of Pretoria, 1984. Staphylococcus aureus is considered as one of the most important food-borne, halotolerant pathogenic bacteria. An investigation was thus performed to determine parameters that could limit its growth in "Shelf Stable Meat Products". Altogether 35 coagulase positive strains were isolated from fresh minced meat and "Shelf Stable Meat Products". Of the isolates 46% were found to be typable using the international basic human set of phages, indicating human origin. Strains relatively sensitive and resistant to low aw and pH were found. The minimal aw for bacterial growth of the aw sensitive and resistant strains were 0,866 and 0,846 respectively. However the type of humectant used to lower aw greatly influenced bacterial growth. When investigating the effect of humectants, its strength for binding water, its bactericidal effects and the concentration of the humectant required to produce the desired aw must be considered. The inorganic acid HCl had the least effect on staphylococcal growth when compared to the organic acids. The minimal pH enabling bacterial growth of the pH sensitive and resistant strains was 5, 1 and 5, 0 respectively when an organic acid was used to adjust the pH, and 4, 43 and 4, 08 respectively when an inorganic acid was used. Acetic acid was the most effective organic acid for growth inhibition. Lowering the aw to 0,925 produced a much greater bacteriostatic effect than lowering the pH to 5, 5. The greatest bacteriostatic effect was obtained at aw 0,925 adjusted with sodium chloride and pH 5, 5 adjusted with gluconic acid. As the aw was lowered, it was found that the amount of cardiolipin in the cell membrane increased, while the amount of phosphatidylglycerol decreased, irrespective of the humectant used to lower the aw. The average diameters of the cocci were found to increase from 0, 87 μm to 1, 25 μm when grown in BHI adjusted to aw 0,925 with glycerol, propylene glycol, sucrose or sodium chloride and to +, 65 μm when the aw was adjusted using sodium lactate. Microbiology and Plant Pathology MSc (Microbiology) 2024-11-27T09:16:07Z 2024-11-27T09:16:07Z 21/11/19 1984 Dissertation http://hdl.handle.net/2263/99530 en © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Growth Staphylococcus Aureus Stress conditions UCTD Growth of Staphylococcus Aureus under stress conditions |
| title | Growth of Staphylococcus Aureus under stress conditions |
| title_full | Growth of Staphylococcus Aureus under stress conditions |
| title_fullStr | Growth of Staphylococcus Aureus under stress conditions |
| title_full_unstemmed | Growth of Staphylococcus Aureus under stress conditions |
| title_short | Growth of Staphylococcus Aureus under stress conditions |
| title_sort | growth of staphylococcus aureus under stress conditions |
| topic | Growth Staphylococcus Aureus Stress conditions UCTD |
| url | http://hdl.handle.net/2263/99530 |