- Bloemfontein, Orange Free State, South Africa
- Lactic Acid Bacteria, Medicinal mushrooms, Ancient Egypt, Ancient Egyptian History, Medicinal Mushrooms: Their Therapeutic Properties and Current Medical Usage with Special Emphasis on Cancer Treatments by Cancer Research UK (the American equivalent to the US National Cancer Institute), 2001., and Indigenous Knowledgeedit
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Research Interests: Geography, Food Science, Biology, Yeast, Fermentation, and 4 moreKefir, Lactose, Yarrowia, and Torulaspora delbrueckii
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The increasing growth of agro-industrial activity resulting in excessive amounts of agri-waste has led to the accumulation of a large quantity of lignocellulosic residues all over the world, in particular, deforestation initiatives for... more
The increasing growth of agro-industrial activity resulting in excessive amounts of agri-waste has led to the accumulation of a large quantity of lignocellulosic residues all over the world, in particular, deforestation initiatives for the removal of invasive trees in South Africa. These lignocellulosic residues are rich in energy resources consisting of a mixture of natural polymers based on lignin, cellulose and hemicellulose. The use of lignolytic fungi such as mushrooms in solid-state fermentation could sufficiently degrade the indigestible lignocellulosic components and add medicinal and nutritional value to otherwise unusable, high-energy waste material. The digestive type of animal for which the potential feed is developed must be identified and considered before deciding on the bioconversion method and process, since the outcomes for obtaining potentially high-quality feeds for non-ruminant and ruminant animals are different. The current study presents the data of the bioconversion of lignocellulosic substrate using solid-state fermentation with the edible and medicinal mushrooms, Ganoderma lucidum, Pleurotusostreatus, and a possible new species, to increase digestibility and nutritional value to be applied as ruminant animal feed. The solid-state fermentation process was optimised and the resulting product analysed for the degradation of the lignocellulosic components. Results indicated that the solid-state fermentation duration and mushroom species were key components in achieving significant degradation. Data obtained after 18 weeks of degradation indicated a significant (p < 0.05) reduction in the acid detergent fibre, acid detergent lignin and neutral detergent fibre fractions of the biomass, with up to 20% reduction in indigestible components. This increase in digestibility could contribute to to increased energy availability for ruminant animals.
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The production of kefir relies on the symbiosis between yeasts, lactobacilli and streptococci. The presence of variable fermenting microflora, however, may be a constraint in producing consistent quality. Consequently, we attempted a... more
The production of kefir relies on the symbiosis between yeasts, lactobacilli and streptococci. The presence of variable fermenting microflora, however, may be a constraint in producing consistent quality. Consequently, we attempted a systematic study of the microbial diversity (with special emphasis on the presence of yeasts) associated with kefir grains from different regions in South Africa. Yeasts were isolated, identified and enumerated from kefir, fermented by different indigenous kefir grains collected throughout the country. All the samples revealed relatively high yeast populations, with counts exceeding 1 × 10lsupg8l/supg cfu ml -1 . Kluyveromyces marxianus, Saccharomyces cerevisiael/ig and Kluyveromyces lactisl/ig were the dominant yeast species isolated. Other species encountered were Saccharomyces unisporus, Zygosaccharomyces rouxiil/ig (formerly Saccharomyces rouxii ), Torulaspora delbrueckiil/ig and Debaryomyces hansenii . The yeast population of traditional South African kefir grains is relatively varied, consisting of non-lactose and lactose-fermenting species, with the latter group dominant. Furthermore, the different kefir grains each hosted a distinct group of microorganisms.
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The increasing growth of agro-industrial activity resulting in excessive amounts of agri-waste has led to the accumulation of a large quantity of lignocellulosic residues all over the world, in particular, deforestation initiatives for... more
The increasing growth of agro-industrial activity resulting in excessive amounts of agri-waste has led to the accumulation of a large quantity of lignocellulosic residues all over the world, in particular, deforestation initiatives for the removal of invasive trees in South Africa. These lignocellulosic residues are rich in energy resources consisting of a mixture of natural polymers based on lignin, cellulose and hemicellulose. The use of lignolytic fungi such as mushrooms in solid-state fermentation could sufficiently degrade the indigestible lignocellulosic components and add medicinal and nutritional value to otherwise unusable, high-energy waste material. The digestive type of animal for which the potential feed is developed must be identified and considered before deciding on the bioconversion method and process, since the outcomes for obtaining potentially high-quality feeds for non-ruminant and ruminant animals are different. The current study presents the data of the bioconversion of lignocellulosic substrate using solid-state fermentation with the edible and medicinal mushrooms, Ganoderma lucidum, Pleurotusostreatus, and a possible new species, to increase digestibility and nutritional value to be applied as ruminant animal feed. The solid-state fermentation process was optimised and the resulting product analysed for the degradation of the lignocellulosic components. Results indicated that the solid-state fermentation duration and mushroom species were key components in achieving significant degradation. Data obtained after 18 weeks of degradation indicated a significant (p < 0.05) reduction in the acid detergent fibre, acid detergent lignin and neutral detergent fibre fractions of the biomass, with up to 20% reduction in indigestible components. This increase in digestibility could contribute to to increased energy availability for ruminant animals.
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Research Interests: Chemical Engineering, Food Science, Food, Biology, Sugar, and 3 moreYeast, Fermentation, and Food Sciences
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ABSTRACT An interesting yeast strain was uncovered which showed an inverse flocculation pattern when cultivated in chemically defined and complex media. When inoculated in a defined medium with glucose as a sole carbon source, this strain... more
ABSTRACT An interesting yeast strain was uncovered which showed an inverse flocculation pattern when cultivated in chemically defined and complex media. When inoculated in a defined medium with glucose as a sole carbon source, this strain immediately flocculated strongly and lost this ability before stationary phase was reached. In a complex malt medium containing glucose, this yeast strongly flocculated throughout the exponential and stationary growth phases. This inverse pattern may be ascribed to a switch in sensitivity of the yeast to flocculate in the presence of glucose as well as pH level, which may, in turn, influence the availability of calcium ions. In both media, matured cells produced protuberances or “wrinkles” upon flocculation as observed by electron and immunofluorescence microscopy. These protuberances may be involved in cell adhesion during the flocculation process.
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ABSTRACT The relationship between 34 Candida species and 51 ascosporogenous yeasts were studied on the basis of long-chain fatty acid composition, coenzyme Q systems, carbon-source utilization patterns and other phenotypic... more
ABSTRACT The relationship between 34 Candida species and 51 ascosporogenous yeasts were studied on the basis of long-chain fatty acid composition, coenzyme Q systems, carbon-source utilization patterns and other phenotypic characteristics. Close relationships were found between nine teleomorph and anamorph yeasts, i. e. Candia norvegensis and Pichia norvegensis, Candida parapsilosis and Lodderomyces elongisporus, Candida krusei and Issatchenkia orientalis, Candida utilis and Pichia jadinii, Candida lusitaniae and Clavispora lusitaniae, Candida pelliculosa and Pichia anomala, Candida cifferri and Stephanoascus cifferri, Candida famata and Debaryomyces hansenii and Candida lipolytica and Yarrowia lipolytica.
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Research Interests: Microbiology, Food Science, Biology, Industrial Biotechnology, Medicine, and 15 moreFood Microbiology, Enumeration, Saccharomyces cerevisiae, Identification, Lactic Acid Bacteria, Yeast, Spectrum, Cheese Ripening, Food Sciences, Yarrowia, Ripening, Thallophyta, Torulaspora delbrueckii, Yarrowia Lipolytica, and Rhodotorula
To gain any therapeutic benefit from eating bio-yogurt, it needs to meet the criterion of a minimum of 106 viable probiotic cells per ml during storage until the expiry date, which is normally 31 days after manufacture. Bio-yogurt from... more
To gain any therapeutic benefit from eating bio-yogurt, it needs to meet the criterion of a minimum of 106 viable probiotic cells per ml during storage until the expiry date, which is normally 31 days after manufacture. Bio-yogurt from three different sources was obtained directly after production, and the samples stored at 4 o C and 10 o C. At three-day intervals during a storage period of 31 days, enumeration of viable probiotic cultures, Lactobacillus acidophilusl/Ig and Bifidobacterium bifidum , and of conventional yogurt starter cultures, Streptococcus thermophilusl/Ig and Lactobacillus bulgaricus , was conducted. Yogurt pH was also measured on every sampling occasion. Viable S. thermophilusl/Ig counts were generally the highest in all three products, ranging from initial values of more than 108 colony-forming units per ml and decreasing between 1 and 2 log cycles during the storage period. Initial levels of L. bulgaricusl/Ig in most samples were higher than 107 cfu/ml and fina...
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Research Interests: Microbiology, Food Science, Statistical Analysis, Biology, Industrial Biotechnology, and 15 moreMedicine, Food Microbiology, Quantitative analysis, Enumeration, Statistical Significance, Cheese, Multiple comparisons, Analysis of Variance, Bacterial growth, Food Sciences, Quantitative Analysis, Agar, Culture Media, Chloramphenicol, and Rose Bengal
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ABSTRACT The cellular long-chain fatty acid composition and electrophoretic karyotypes of 117 strains of Candida were determined and used as a basis for a taxonomic study of this genus. Three major groups subdivided into 15 entities were... more
ABSTRACT The cellular long-chain fatty acid composition and electrophoretic karyotypes of 117 strains of Candida were determined and used as a basis for a taxonomic study of this genus. Three major groups subdivided into 15 entities were proposed which are differentiated by the absence or presence of linoleic (C18 : 2) and linolenic acid (C18 : 3) and different electrophoretic karyotypes. Interesting correlations between fatty acid composition, electrophoretic karyotypes, coenzyme Q systems, G+C contents, serological data and proton magnetic resonance spectra were observed. The coordinate use of these different phenotypic characters, provides a convenient method to establish close relationships between the different strains and species. Cellular long-chain fatty acid composition and electrophoretic karyotypes both proved to be valuable criteria in the differentiation of species of the genus Candida.
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ABSTRACT The relationship between 34 Candida species and 51 ascosporogenous yeasts were studied on the basis of long-chain fatty acid composition, coenzyme Q systems, carbon-source utilization patterns and other phenotypic... more
ABSTRACT The relationship between 34 Candida species and 51 ascosporogenous yeasts were studied on the basis of long-chain fatty acid composition, coenzyme Q systems, carbon-source utilization patterns and other phenotypic characteristics. Close relationships were found between nine teleomorph and anamorph yeasts, i. e. Candia norvegensis and Pichia norvegensis, Candida parapsilosis and Lodderomyces elongisporus, Candida krusei and Issatchenkia orientalis, Candida utilis and Pichia jadinii, Candida lusitaniae and Clavispora lusitaniae, Candida pelliculosa and Pichia anomala, Candida cifferri and Stephanoascus cifferri, Candida famata and Debaryomyces hansenii and Candida lipolytica and Yarrowia lipolytica.
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ABSTRACT Pyrolysis-gas liquid chromatography analysis were carried out on 28 strains of yeasts belonging to the Ascomycetes. A large number of quantitative and qualitative differences were observed in the different pyrograms. These... more
ABSTRACT Pyrolysis-gas liquid chromatography analysis were carried out on 28 strains of yeasts belonging to the Ascomycetes. A large number of quantitative and qualitative differences were observed in the different pyrograms. These results were compared and the similarities calculated by computer analysis. With pyrolysis, different yeasts could be classified into groups which correspond with the present classification system. The 28 strains studied could be separated within 49 h, in comparison with the 7–10 days with conventional methods.
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Summary Brevibacterium linens is an important species in dairy products rendering a specific ta- ste and aroma to numerous smear ripened and blue veined cheeses due to proteolysis. However, the presence of the species in South African... more
Summary Brevibacterium linens is an important species in dairy products rendering a specific ta- ste and aroma to numerous smear ripened and blue veined cheeses due to proteolysis. However, the presence of the species in South African blue veined cheeses is undesirable and consumers demand the product void of the species. Accordingly, numerous methods including microbial inhibition using fungi and bacterial probiotic cultures with possible inhibitory effects were applied in an attempt to inhibit the species. None of the fungi, however, proved to be successful, whereas Lactobacillus rhamnosus and Bifidobacterium lac- tis, two typical probiotic species applied in dairy products, showed inhibitory effects aga- inst B. linens when tested using the spot-on-lawn assay.
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Research Interests: Microbiology, Interaction, Industrial Biotechnology, Food Microbiology, Lactic Acid Bacteria, and 14 moreAnimals, Lactobacillus, Bacteria, Milk, Cheese, Fermentation, Bacterial growth, Dairy Products, Food Contamination, Food Sciences, Yeasts, Microbiological Quality, food handling, and Environmental factor
The volatile organic compounds present in 18 Zimbabwean naturally fermented milk (amasi) samples and those produced by various yeasts, lactic acid bacteria (LAB) and yeast/ LAB combinations were determined using headspace gas... more
The volatile organic compounds present in 18 Zimbabwean naturally fermented milk (amasi) samples and those produced by various yeasts, lactic acid bacteria (LAB) and yeast/ LAB combinations were determined using headspace gas chromatography. The yeast strains used were: Candida kefyr 23, C. lipolytica 57, Saccharomyces cerevisiae 71, C. lusitaniae 68, C. tropicalis 78, C. lusitaniae 63, C. colliculosa 41, S. dairenensis 32, and Dekkera bruxellensis 43, and were coded Y1 to Y9, respectively. The LAB strains used were Lactococcus lactis subsp. lactis Lc39, L. lactis subsp. lactis Lc261, Lactobacillus paracasei Lb11, and L. lactis subsp. lactis biovar. diacetylactis C1, and were coded B1 to B4, respectively. Some of the volatile organic compounds found in amasi were acetaldehyde, ethanol, acetone, 2-methyl propanal, 2-methyl-1-propanol and 3-methyl-1-butanol. However, the levels of volatile organic compounds in the naturally fermented milk (NFM) samples varied from one sample to anothe...
Aggregation of ascospores has been discovered in the yeast Dipodascopsis uninucleata. When this yeast is cultivated to reach the sexual reproductive stage, small ascospores are individually released from the tip of a sac-like ascus which... more
Aggregation of ascospores has been discovered in the yeast Dipodascopsis uninucleata. When this yeast is cultivated to reach the sexual reproductive stage, small ascospores are individually released from the tip of a sac-like ascus which then aggregate in orderly clusters. Acetylsalicylic acid (ASA) inhibited ascospore release and subsequent ordered aggregation process. We suggest that novel ASA-sensitive oxidised fatty acids (3R-hydroxy-oxylipins) and small hooks located on the surface of these ascospores, are involved.
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Summary Varieties of blue veined cheese were analyzed regularly during different stages of ma- nufacturing and ripening to determine the origin of contaminating the yeasts present in them, their population diversity and development until... more
Summary Varieties of blue veined cheese were analyzed regularly during different stages of ma- nufacturing and ripening to determine the origin of contaminating the yeasts present in them, their population diversity and development until the end of the storage. Yeast di- versity and development in the inner and outer core of the cheeses during ripening were also compared. Air samples
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ABSTRACT A historical review of the genus Candida Berkhout is given. This includes a chronological account of various taxonomists' views of the past 78 years which led to the present demarcation of this anamorphic genus and the... more
ABSTRACT A historical review of the genus Candida Berkhout is given. This includes a chronological account of various taxonomists' views of the past 78 years which led to the present demarcation of this anamorphic genus and the subsequent development of a homogeneous taxon with only ascomycetous affinities.
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... 97 17.00 + 0.00 Canada's Atlantic Coastal Action Program: A communitybased approach to collective governance James E Ellsworth,a Lawrence E Hildebranda E. Anne Gloverb a ... Moreover, the coastal environment is... more
... 97 17.00 + 0.00 Canada's Atlantic Coastal Action Program: A communitybased approach to collective governance James E Ellsworth,a Lawrence E Hildebranda E. Anne Gloverb a ... Moreover, the coastal environment is intrinsically linked to the socio cultural heritage of the region ...
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J. Inst. Brew. 110(3), 207-212, 2004 In this study we uncovered that Saccharomyces cerevisiae UOFS Y-2330 does not only demonstrate inverse flocculation, but is also characterised by two different lipid turnover patterns. Dur- ing Flo1... more
J. Inst. Brew. 110(3), 207-212, 2004 In this study we uncovered that Saccharomyces cerevisiae UOFS Y-2330 does not only demonstrate inverse flocculation, but is also characterised by two different lipid turnover patterns. Dur- ing Flo1 phenotype flocculation, this yeast showed two neutral lipid accumulating stages (i.e. at 8 h and from 12 h). This is probably triggered by flocculation, which
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ABSTRACT The cellular long-chain fatty acids of 72 strains representing 29 species of brewery yeasts were extracted by saponification and analysed as methyl esters by gas chromatography. With this method, it was possible to distinguish... more
ABSTRACT The cellular long-chain fatty acids of 72 strains representing 29 species of brewery yeasts were extracted by saponification and analysed as methyl esters by gas chromatography. With this method, it was possible to distinguish between Saccharomyces cerevisiae and five other groups from the brewery industry, only four hours after they were obtained from 48 h old cultures under standard conditions. This compares favourably with the 7 to 10 days for conventional methods.