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Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics
Dissertation (Ph. D.) -- University of Stellenbosch, 1998.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613830057558016 |
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| access_status_str | Open Access |
| author | Du Toit, Margaretha |
| author2 | Holzapfel, W. H. |
| author_browse | Du Toit, Margaretha Holzapfel, W. H. |
| author_facet | Holzapfel, W. H. Du Toit, Margaretha |
| author_sort | Du Toit, Margaretha |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Dissertation (Ph. D.) -- University of Stellenbosch, 1998. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/55914 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:42:21.587Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/55914 Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics Du Toit, Margaretha Holzapfel, W. H. Dicks, L. M. T. Stellenbosch University. Faculty of Science. Dept. of Microbiology. Lactic acid bacteria Gastrointestinal system Dissertations -- Microbiology Dissertation (Ph. D.) -- University of Stellenbosch, 1998. Lactic acid bacteria (LAB), especially Lactobacillus, Enterococcus and Bifidobacterium spp., are normal inhabitants of the gastrointestinal tract (GIT). Probiotics are defined as "a live microbial feed supplement, which beneficially affects the host by improving its microbial balance". Lactic acid bacteria are associated with health effects in the GIT and may include alleviation of lactose intolerance, stabilisation of the intestinal flora, reduction of serum cholesterol levels, stimulation of the immune system, anticarcinogenic effects, inhibition of pathogens, alleviation of diarrhoea and the relieve of veginitis. The bile salt hydrolase (BSH) hypothesis was addressed. It claims that the deconjugation of bile salts may contribute to lower cholesterol levels as deconjugated bile salts are excreted more readily from the GIT than conjugated bile salts. The BSH enzyme is responsible for the deconjugation of bile acids, conjugated with either glycine or taurine, thereby resulting in free bile salts. The two strains of Lactobacillus johnsonii and one strain of Lactobacillus reuteri to be used as probiotic supplement were isolated from pigs (host specificity) and were selected for the following characteristics: high BSH activity, bile salt resistance, low pH tolerance and the production of a bacteriocin active against other LAB and pathogenic bacteria such as Clostridium perfringens, Staphylococcus aureus and Streptococcus mutans. The minipigs received a high-cholesterol, high-fat diet for 17 weeks during which hypercholesterolemia and a "steady-state" was reached. They then received the probiotic supplement (2×10^11) CFU/minipig/day) with the "Western style" diet for five weeks. During this period the cell counts of faecal Lactobacillus spp. increased, the serum cholesterol levels were reduced by ca. 5%, concomitant with a non-significant increase in triglycerides. No effect on faecal pH (constant between 7.0 and 8.0) and an increase of the moisture content of faeces was observed. The two faecal enzymes 𝛽-glucuronidase and azoreductase, which have the ability to convert procarcinogens into carcinogens, were reduced significantly in the faecal contents of minipigs. The cell counts for total anaerobes, eubacteria, clostridia and Enterobacteriaceae slightly increased whereas that of Bacteroides, Staphylococcus and Enterococcus spp. decreased. Doctoral 2012-08-27T11:37:17Z 2012-08-27T11:37:17Z 1998 Thesis http://hdl.handle.net/10019.1/55914 en Stellenbosch University 216 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Lactic acid bacteria Gastrointestinal system Dissertations -- Microbiology Du Toit, Margaretha Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| title | Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| title_full | Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| title_fullStr | Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| title_full_unstemmed | Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| title_short | Isolation, identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| title_sort | isolation identification and characterisation of lactic acid bacteria with potential probiotic characteristics |
| topic | Lactic acid bacteria Gastrointestinal system Dissertations -- Microbiology |
| url | http://hdl.handle.net/10019.1/55914 |
| work_keys_str_mv | AT dutoitmargaretha isolationidentificationandcharacterisationoflacticacidbacteriawithpotentialprobioticcharacteristics |