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Theses and dissertations (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/6

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Subject: search.filters.subject.Probiotics

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    The prebiotic effects of amadumbe (Colocasia Esculenta) and okra (Abelmoschus esculentus) mucilage
    (2023) Gajadhar, Sharmista; Amonsou, Eric Oscar; Mchunu, Nokuthula Peace
    Prebiotics have been shown to aid in the improvement and maintenance of human health through positive manipulation of gut microbiota. Diet-induced changes in gut microbial diversity has been recognized as a factor which contributes to the rising epidemics of chronic illnesses in both developed and developing countries. Traditional crops, amadumbe (Colocasia esculenta) and okra (Abelmoschus esculentus (L.) Moench) offer nutritional security to many communities in South Africa. These crops are rich in mucilage and are presumed prebiotics. Structural composition and functional properties of polysaccharides like mucilage are suggested to influence their fermentability by gut microbiota and potential health effects. The purpose of this study was to investigate the prebiotic effects of amadumbe and okra mucilages for potential application as dietary supplements. Mucilage was extracted from amadumbe and okra by cold water extraction. Purified mucilage was obtained by Sevag method, lipid removal and thereafter dialyzed. The composition and structure of crude and purified mucilage were analyzed using Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC) and high pressure liquid chromatography (HPLC). Functional properties including water and oil holding capacity, swelling and solubility were determined. The prebiotic potential of amadumbe and okra mucilage was carried out by in- vitro fermentation using human faecal sample. Glucose was the common monosaccharide present in both amadumbe and okra mucilage. Monosaccharides present in amadumbe mucilage were arabinose, mannose and xylose, while galactose, ribose and rhamnose were the main monosaccharides present in okra mucilage. The presence of β-glucan was found to be higher 0.20 g/100 g in amadumbe mucilage than in okra mucilage 0.07 g/100 g. The resistant starch content in amadumbe mucilage was higher 4 g/100 g than in okra mucilage 0.7 g/100 g. Asparagine, proline, glutamine, and threonine were the most common amino acids found in both amadumbe and okra mucilage samples. Purified amadumbe and okra mucilage displayed the same characteristic peaks as crude amadumbe and okra mucilage in the FT-IR spectrum but at a lower intensity suggesting that purification contributed to a more stable and uniform structure. The FT-IR spectrum indicated the presence of uronic acid and hydroxyl groups which confirm the existence of carbohydrate in both amadumbe and okra mucilage. The molecular weight of crude amadumbe and okra mucilages ranged between 219 and 224 kDa while molecular weight of purified amadumbe and okra mucilage ranged between 220 and 244 kDa. The purification process was seen to improve functional properties such as the water holding capacity, swelling and solubility of mucilages. In comparison to okra mucilage, crude and purified amadumbe mucilage showed low water holding capacity 5 and 9 g/100 g and high percentage solubility 61 and 73%. Amadumbe mucilage had a slightly higher oil holding capacity 11 g/100 g in comparison to okra mucilage 10 g/100 g. During in-vitro fermentation, inulin (positive control) rapidly decreased the pH of the fermentation medium from 7.0 to 6.5, in comparison to amadumbe (7.0 to 6.7) and okra (7.0 to 6.8) mucilage. At the end of fermentation inulin had maximum gas production of 233.19 mL, followed by amadumbe mucilage 158.98 mL and okra mucilage 113.98 mL. These results suggest inulin is more easily fermented by microbes compared to amadumbe and okra mucilage. Gut microbiota analysis at phylum level showed that amadumbe mucilage stimulated the proliferation of Actinobacteria and reduced the presence of Firmicutes in comparison to okra mucilage. At species level, okra mucilage promoted the growth of Bacteroidaceae bacteroidetes, Bacteroides ovatus and Bacteroides uniformis. These species are known to assist in protection of the gut and are capable of providing nutrients to other microbial species. This suggest that amadumbe and okra mucilages are fermented differently by gut microbiota possibly due to differences in their structure and composition. This study concluded that amadumbe and okra mucilages has potential to be utilized as an emerging prebiotic in food applications or as supplements.
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    Development of a bioprocess technology for the production of Vibrio midae, a probiotic for use in abalone aquaculture
    (2019) Moonsamy, Ghaneshree; Singh, Suren; Lalloo, Rajesh
    The abalone industry of South Africa is under severe pressure due to illegal harvesting and poaching of this seafood delicacy. These abalones are harvested excessively; as a result, these animals do not have a chance to replace themselves in their habitats, ensuing in a drastic decrease in natural stocks of abalone. Abalone, has an extremely slow growth rate, and takes approximately four years to reach a size that is market acceptable, therefore, it was imperative to investigate methods to boost the overall growth rate and immunity of the animal. The University of Cape Town (UCT) began research, which resulted in the isolation of two microorganisms, a yeast isolate Debaryomyces hansenii and a bacterial isolate Vibrio midae, from the gut of the abalone and characterised them for their probiotic abilities. This work resulted in an internationally competitive concept technology that was patented. The next stage of research was to develop a suitable bioprocess to enable commercial production. Numerous steps were taken to develop an efficient production process for V. midae, one of the isolates found by UCT. The initial stages of research resulted in the development of a stable and validated cell bank which allowed the development of a robust inoculum stage. This was followed by optimization of temperature and pH which resulted in improved probiotic production at a temperature of 30oC and a pH of 6.5. Once these critical growth parameters were established further media optimization studies were performed. The two key nutrient supplements investigated were corn steep liquor (CSL) and High Test Molasses (HTM) due to their suitability, availability and affordability. The optimization of CSL (6.4 g.l-1) and HTM (24 g.l-1) concentrations in the growth medium resulted in a 180% increase in cell concentration, a 5716-fold increase in cell productivity and a 97.2% decrease in the material cost of production when compared to the base case technology. Furthermore, a stable market ready liquid probiotic product, containing viable but not culturable (VBNC) state of Vibrio midae cells, was developed during the downstream processing aspect of the study. Finally, the validation of this production technology at full manufacturing scale was demonstrated which further enhances the attractiveness and commercial feasibility of this probiotic production process.
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    Isolation and characterization of prebiotic oligosaccharides from algal extracts and their effect on gut microflora
    (2016) Hadebe, Nontando; Odhav, Bharti
    Prebiotics are defined as non-digestible oligosaccharides (NDOs) or polysaccharides (NDPs), which promote the growth of beneficial lactic acid bacteria in the colon. Algae are rich in polysaccharides and can be exploited as prebiotics for functional food ingredients to improve human and animal health. Currently, inulin is the most widely used ingredient in the prebiotics market, which is produced from live plants and requires expensive production processing. There is a vast repository of marine life with algae as a major source of nutrients. Therefore, this study provides an alternative source for prebiotic production and examines marine and freshwater algae that promote the growth of two strains of Lactobacillus delbrueckii subs. (Lactobacillus lactis and Lactobacillus bulgaricus) and one strain of Bifidobacterium spp. (Bifidobacterium longum). Monosaccharides of the oligosaccharide fraction of marine and freshwater algal extracts were investigated with the use of thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) after acidic hydrolysis of cell matrix polysaccharides. A total of fifty-five marine and freshwater aqueous algal extracts were assessed for their effect on the growth of L. lactis, B. longum and L. bulgaricus over a 96 hour period. Relative to the negative control, 34.5% algal extracts showed improved growth on one or more probiotic bacteria. The optimum time for maximum bacterial growth was noted at 48 h for all the tested aqueous algal extracts. Five marine and freshwater algal cultures (Spirulina platensis, Chlorococcum spp., Dunaliella salina, Scenedesmus magnus, Chlorella spp. and algal extract no. 48) from various aquatic environments in Kwa-Zulu Natal showed the best growth dynamics and demonstrated the greatest potential as sources of biomass for prebiotic production. These algal extracts were able to significantly increase the growth of at least one of the three probiotic bacteria (p < 0.05). Aqueous algal extract from S. platensis was regarded as the best algal source for prebiotics as it demonstrated a greater stimulatory effect on the growth of all three probiotic bacteria (L. lactis, B. longum and L. bulgaricus) compared to tested aqueous algal extracts and the inulin used as a positive control. The results obtained by HPLC for characterization confirmed TLC data, as xylose and galactose were detected by both chromatograms. These data indicated that xylose and galactose were present in aqueous algal extracts from S. magnus and S. platensis and galactose in aqueous algal extract no. 48. Xylose was most abundant in aqueous algal extracts from S. platensis (3mg/ml) and S. magnus (2.3mg/ml). In conclusion aqueous algal extracts from S. platensis, Chlorococcum, D. salina, S. magnus, Chlorella and algal extract no. 48 are potential sources for prebiotic production. Spirulina platensis extract was regarded as the best algal source. Xyose and galactose characterized by HPLC in algal extracts make up oligosaccharides that function as prebiotic compounds for stimulation of probiotic bacteria. There is a great scope for successful production of prebiotics from algal sources in South Africa.
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    Dietary modulation of the human colonic microbiota through plant-derived prebiotic compounds
    (2007) Kassim, Muhammad Arshad
    The human gut microbiota play a major role in host health, and attempts are being made to manipulate the composition of the gut microbiota-increase the composition of bacterial groups, such as lactobacilli and bifidobacteria that are perceived as exerting health promoting properties. These bacteria defined as food supplements (probiotics) beneficially affect the host by improving the intestinal microbial balance, and have been used to change the composition of the colonic microbiota. However, such changes may be transient, and the implantation of exogenous bacteria therefore becomes limited. In contrast, prebiotics are naturally occurring carbohydrates that are classified as non-digestible oligosaccharides present in edible plants. These carbohydrates enter the colon as intact compounds, elicit systemic physiological functions and act as fermentable substrates for colonic microflora-influencing the species composition and metabolic characteristics of intestinal microflora providing important health attributes. Currently, a widely marketed prebiotic, inulin is extracted from plants of the family Asteraceae. There are many unexploited plants that are regularly consumed and that may have a prebiotic effect or can have very high levels of inulin which could make them commercially viable. In this study, we investigated prebiotic compounds, especially inulin from locally growing, non-commercialised leafy plants. The aqueous extracts of 22 plants from the families Asparagaceae, Alliaceae, Asteraceae, Solanaceae, Cucurbitaceae, Amaranthaceae, Acanthaceae, Polygonaceae, Portulaceae, Fabaceae, Chenopodiaceae, Pedaliaceae and Apiaceae from Kwa-Zulu Natal were investigated for a prebiotic effect using a modified batch-culture technique with Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus reuteri and Bifidobacterium longum, four common probiotics and the inulin content of the plants was determined using high performance liquid chromatography. Of the 22 plants studied, Solanum nigrum, Amaranthus spinosus, Amaranthus hybridus, Asystasia gangetica, Senna occidentalis, Cerathoteca triloba, Asparagus sprengeri, Tulbaghia violacea, Sonchus oleraceus and Taraxacum officinale exhibited a prebiotic effect. The prebiotic effect of the Taraxacum officinale, Sonchus oleraceus and Asparagus sprengeri extracts on L. lactis and L. reuteri was higher than or equivalent to inulin-a commercial prebiotic. In this study, Sonchus oleraceus exhibited the best prebiotic effect-was the only plant to stimulate all the probiotics including B. longum. Of all the plants analysed, Asparagus sprengeri tuber contained the highest amount of inulin (3.55%).