Theses and Dissertations
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Item Characterization Of Phenotypic Traits Linked To Anthracnose Resistance And Their Impact On Farmer Adoption Of Common Bean In Tanzania(NM-AIST, 2025-03) Kadege, EdithTanzania is the top bean producer in Africa and seventh globally, exporting half of beans to neighboring nations. However, only 14% of Tanzanian farmers use improved bean varieties, leading to suboptimal productivity. Diseases, like anthracnose significantly hinder adoption. From 2021-2023, research was conducted in Tanzania to identify phenotypic traits associated with anthracnose resistance and farmers-preferred traits for adopting bean varieties. Twenty-two bean genotypes were evaluated in anthracnose hotspot fields and in screen house to validate resistance. Eighteen genotypes were further assessed under local conditions to evaluate performance and farmers-preferred traits. Phenotypic traits like anthracnose infection score, plant vigor, days to maturity, plant stands at harvest and grain yield were recorded and analyzed using R statistical software. Results revealed 75% of phenotypic traits are positively correlated with anthracnose resistance, with strong correlations (P≤0.001) on days to maturity, plant stands at harvest, plant vigor and grain yield. The NUA 48, NUA 64, Sweet Violet and VTT 923-23-10 demonstrated resistance and high yields. Significant differences (P≤0.001) were observed among genotypes, environments and their interactions, influencing disease resistance and grain yield. Advanced breeding lines outperformed commercial checks by 56%. Anthracnose incidence varied regionally, with higher rates in Northern Tanzania (22.7%) compared to Lakezone (10%) and Southern regions (5.8%). Highest incidence in Northern is due to higher soil inoculum levels sustained by two cropping seasons. In contrast, Southern highlands with single cropping season and continuous crop rotation, these practices help reduce anthracnose inoculum. The NUA 48, NUA 64, Sweet violet and VTT923-23-10 were identified as top perfoming genotypes in terms of yield and farmer preference in Tanzania. High yield, market preference, and disease resistance were key selection criteria. Cooking suitability with banana and intercropping compatibility emerged as unique farmer preferences, suggesting the importance of incorporating these traits in future variety development. Based on these findings, phenotypic traits like plant vigour, days to maturity, plant stands at harvest, and grain yield can be considered in breeding efforts. The NUA 48, NUA 64, Sweet violet and VTT 923-23-10 are proposed for release dueto their anthracnose resistance, adaption to local conditions, and preference by farmers in Tanzania.Item Effects Of Adjunctive N-Acetyl Cysteine (Nac) In Tuberculosis Patients In Mbeya Region, Tanzania(NM-AIST, 2025-07) Mapamba, DanielHalf of the global health burden of tuberculosis (TB) is due to post-TB disability and mortality occurring despite microbiologic cure. Sustained TB infection elicits an immune response against Mycobacterium tuberculosis and overproduces TNF-α and reactive oxygen species (ROS), which help to kill or contain the pathogen. However, they cause lung injuries. Adjunctive, host-directed therapies have been proposed to address these concerns. One such candidate, N-acetylcysteine (NAC), has been in clinical use since the 1970s to prevent fatal hepatic necrosis following acetaminophen poisoning. The usefulness of NAC in replenishing glutathione (GSH) and treating various diseases, including COVID-19, has been studied. The present study investigated the effect of NAC in TB treatment, focusing on the levels of glutathione, TNF-α, IL-10, hemoglobin, and its antibacterial activity. A prospective, open label, randomized controlled trial enrolled 140 adult TB patients from health facilities in the Mbeya region, who had confirmed pulmonary TB by Gene Expert, with a cycle threshold (Ct) value ≤27 and were Rifampicin-sensitive, and had chest X-rays showing moderate or far advanced lung disease. Participants were randomized to receive standard anti-TB (2HRZE/4HR) with or without NAC 600 mg BID on days 1–112. Whole blood samples were collected for measurement of hemoglobin, bactericidal activity, glutathione, TNF-α, and IL-10 expression by the ELISA method from Calorimetric Arbor Assays and R&D Systems, and sputum samples were used to assess M. tuberculosis burden. NAC treatment rapidly increased total glutathione (P<0.0001), but levels did not reach those of healthy volunteers (P<0.001). NAC reduced TNF-α expression levels (P = 0.011) without affecting IL-10 and accelerated hemoglobin recovery in participants with low values at baseline. The NAC did not affect the killing of MTB in ex vivo whole blood culture but slowed the clearance of MTB from sputum (P = 0.003). In summary, oral NAC restored GSH and resolved anemic TB patients more rapidly; it also reduced TNF-α without affecting IL-10 and antimycobacterial host defenses or treatment activity. The decline in GSH after stopping NAC may indicate sustained inflammation and oxidative stress despite apparently successful TB treatment. The reduction of the markers of oxidative stress and inflammation by NAC may account for its effects on the recovery of lung function in TB. Thus, before its use is approved, more research on various dosages and extended follow-up in various group demographics is warranted.Item Ecological Dynamics Of Helichrysum (Asteraceae) Shrubs Cover And Their Effect On Orchids In Kitulo National Park, Tanzania(NM-AIST, 2025-08) Mgimba, ChristopherGrassland ecosystems are undergoing major ecological transformations due to anthropogenic disturbances. In protected areas such as Kitulo National Park (KNP) in Tanzania, the spread of dwarf Helichrysum shrubs has potential impact on native herbaceous plant species like orchids. While Helichrysum species are known to thrive in degraded, low-nutrient soils, there is limited empirical evidence on the mechanisms driving their spread and the ecological consequences of their encroachment in tropical montane grasslands. This study aimed to assess the drivers of Helichrysum expansion and their ecological interaction with orchids. Fieldwork was conducted across multiple zones within KNP, categorized based on their historical land use as ‘grazed crop’, ‘grazed’, and ‘wild’. A total of 222 quadrats were established to assess the abundance and diversity of Helichrysum and orchid species. Soil samples were analyzed to determine nutrient composition, and controlled experiments were conducted to evaluate Helichrysum regeneration under different fire treatments (unburned, early burned, late burned) and disturbance regimes (cutting stems, uprooting). Additionally, germination trials were carried out in the laboratory to test the effect of fire-simulated temperatures on Helichrysum splendidum seed germination. The orchid species' responses were evaluated in terms of relative interaction intensity (RII), physiological vigor, and flowering metrics under varying Helichrysum cover levels. Results revealed that Helichrysum splendidum was the most dominant shrub species, with significantly higher abundance in historically disturbed zones; the 73% and 46% more in ‘grazed crop’ and ‘grazed’ areas, respectively, than in the ‘wild’ zone. Orchid richness and abundance significantly declined with increasing Helichrysum cover. Fire played a dual role while complete burning induced vigorous Helichrysum resprouting, early burns significantly suppressed seedling recruitment and reduced seed bank density. Temperature treatments confirmed that seeds exposed to 80°C and 110°C had significantly lower germination than unheated and those heated at 50°C (p < 0.001), suggesting fire-inhibits germination of Helichrysum seed. This study concludes that the spread of Helichrysum shrubs in Kitulo National Park is largely driven by legacy effects of past land use and soil nutrient depletion. High shrub cover negatively affects orchid diversity and species richness. Management strategies that include burning early in the season and physically removing shrubs can reduce the spread of Helichrysum and support the protection of native orchid species and the variety of plants in montane grasslands.Item Evaluation Of The Malaria Transmission-Reducing Activity Of Pfs25-Imx313/Matrix-M Vaccine And Naturally Acquired Antibodies In Tanzanian Volunteers(NM-AIST, 2025-07) Mulamba, CharlesMalaria is still a public health challenge in Tanzania, control relies on the use of artemisinin-based combination therapies and insecticide-treated materials. The effectiveness of these interventions is threatened by drug and insecticide resistance in parasites and vectors respectively. Transmission-blocking interventions are therefore needed to supplement the current interventions. This study evaluated the ability of vaccine-induced Pfs25 antibodies, to block malaria parasite development in mosquitoes, following a Phase1 vaccine trial in Bagamoyo, Tanzania, between 2021 and 2023. The transmission reducing activity (TRA) was evaluated via Standard Membrane Feeding Assays (SMFAs), where laboratory mosquitoes were fed with a mixture of test or control antibodies and cultured Plasmodium falciparum gametocytes. The TRA was determined as the reduction in the number of oocysts by test antibodies compared to a negative control lacking blocking antibodies. In addition, a survey was conducted to determine the seroprevalence of natural antibodies to malaria antigens; Pfs25, Pfs230D1M, and Pfs48/45, as well as the malaria prevalence in 467 participants from five villages in Bagamoyo district. The malaria and natural antibody survey were conducted as a baseline for phase1 evaluation of Pfs25-IMX313/Matrix-M vaccine candidate. Trial results indicated that the Pfs25-IMX313/Matrix-M vaccine induced long-lasting antibodies, which promoted significant TRA in 18 of the 20 vaccinated participants. Survey findings showed that 23.5% (110/467) of the participants tested positive for malaria, and 24% of the malaria-positive participants had the sexual form of malaria (gametocytes) responsible for transmission. Regression analysis showed that gametocytes were more likely to be present among male participants than female participants [ORa: 2.79 (95% CI: 1.19 – 6.59) p=0.019]. The survey results further indicated that the seroprevalence of Pfs230D1M IgG was 56% (157/281), whereas that of Pfs48/45 IgG was 49% (141/291). Seroprevalence for anti-Pfs230 and anti-Pfs48/45 IgG increased significantly with participants’ age, with adults more likely to have antibodies than children; for Pfs230 [adjusted OR 3.18, (95% CI: 1.85 - 5.57), p=<0.0001], and Pfs45/48 [OR 3.11, (95% CI: 1.83 - 5.29), p = <0.0001]. When Pfs48/45 and Pfs230 seropositive serum was tested in the SMFAs, only two (2) of the 10 participants demonstrated significant TRA. We conclude that a transmission-blocking vaccine will be a great addition to the current malaria interventions, and children as well as adults should be targeted, if malaria elimination to be achieved. The Pfs25-IMX313/Matrix-M vaccine in this study should be further developed in combination with another transmission-blocking target such as Pfs230D1M or Pfs48/45.Item Exploring The Therapeutic Potential Of Urolithin A For Healthy Ageing: In Silico Study(NM-AIST, 2025-08) Massanga, CarolineUrolithin A, an active precursor derived from the metabolism of ellagitannins in rats and humans, is known for its potential health benefits, including stimulating mitophagy and promoting musculoskeletal function. While experimental studies have demonstrated Urolithin A’s potential to enhance cellular health, the detailed molecular interactions through which Urolithin A exerts its effects are not fully elucidated. Hence, this study investigated the anti inflammatory, anti-oxidation and neuro-protective abilities of Urolithin A in selected targets using molecular docking and molecular dynamics simulation methods. Molecular docking studies revealed the strong affinity for receptors involved in inflammation activities, including human p38 MAP kinase (4DLI) with ˉ10.1 kcal/mol interacting with SER252, LYS249 and ASP294 residues. The binding energy in the 5KIR target was ˉ8.6 kcal/mol, interacting with GLN203 through hydrogen bond, and lastly, 1A9U with an affinity of ˉ6.8 with no hydrogen bond formed with Urolithin A and interacts with van der Waals interactions. In oxidativetargets, the influence of Urolithin A was observed in 1OG5 with ˉ7.9 kcal/mol interacting with GLN185, PHE447. For the 1M17 target, the binding affinity was ˉ7.7 kcal/mol, interacting with THR95 residue and 1ZXM target at ˉ7.4 kcal/mol, interacting with TYR36, TYR216, and LEU234 residues. The neuro-protective ability of Urolithin A was observed in selected targets for acetyl cholinesterase; the binding energy was ˉ9.7 kcal/mol interacting with van der Waals and π der Waals and π interactions; for the 1GQR target, the binding energy was ˉ9.9 kcal/mol interacting with van interactions and for β-amylase (1iyt) the binding energy was ˉ5.5 forming hydrogen bond with SER8, GLN15 residues. Molecular Dynamics simulations at 100 ns of Urolithin A compared with reference 4DLI. The Urolithin A-4DLI complex exhibited greater stability than the reference receptor, as confirmed by RMSD, RMSF, Radius of Gyration, Hydrogen bond and SASA analyses.Item Cashew Wastes Biomass in Tanzania Auditing and Characterization: A potential bioresource for production of value-added products(2025-06-27) Mwema, Hadija; Kassuwi, Shaaban; Mosha, Prosper; Mshandete, AnthonyCashew waste biomass presents a valuable resource for production of value-added products. This study evaluated potential for valorization of cashew wastes (husks, apples and leaves) generated in Mtwara, Tanzania through integrating quantitative and laboratory analysis methods. Chemical composition of cashew waste analyzed were nitrogen, phosphorus, pH, moisture content, total organic matter, ash content, crude fiber, and conductivity. Nitrogen contents of cashew waste including husks, apples and leaves ranged between 1.46 – 2.58%, phosphorus was 0.03 – 0.38%, moisture content between 5.63-23.10%, and pH ranged between 4.44 -5.91. Solid wastes were characterized by crude fiber content in the range of 0.32-0.49 g, ash content between 6.65 – 14.24% and total organic matter content between 95-97%. Results showed that the annual generation of cashew wastes was estimated at 458,874 tons. Out of these, 66% were dried cashew apples, 33% cashew nut shells and 1% cashew husks. These wastes can be transformed into food, feed, bio-energy and bio-based products using bioconversion technologies in integrated and sustainable manner. A scheme for utilization of cashew waste into value added products has been proposed which contributes to environmental preservation. This approach offers a circular economic growth and aligns with global sustainable development goals by responsible consumption and production.Item Status, physiognomies and economic viability of hydroponic lettuce production in selected areas of Sothern TANZANIA and Central UGANDA(2023-08) Gumisiriza, MargaretThere is an increasing interest and research in soilless farming due to its ability to enhance food production amidst challenges presented by urbanization. However, the adoption of this technology is still very limited in East Africa. This main objective of the research was to study the appropriateness of hydroponics as a feasible urban cropping system for improved vegetable production and accessibility in Uganda. An assessment on status of hydroponics in Northern Tanzania and Central Uganda was carried out using google questionnaires and face-face interviews which revealed limited uptake of the technology majorly due to the high initial costs required. An experiment was set up in central Uganda to evaluate the performance of red and green leafy lettuce produced using a non-greenhouse and non-circulating hydroponic system. Parameters assessed included; plant height, root length, number of leaves, leaf width, fresh weight and dry matter content. Data was analyzed using 2 sample T-test under origin software. A significant difference was noted at harvest for dry matter content (P=0.02, P=0.01), fresh weight (P=0.03, P=0.02) and root length (P=0.01, P=0.02) between red and green lettuce grown under soil and hydroponics in that order at P < 0.05. An economic analysis was done on the system to assess its profitability. Budgeting techniques results showed: Net present value (16.37$), Internal rate of return (12.57%), Profitability index (1.1) and non-discounted payback period (4,5) for annual crop production. Net present value was sensitive to changes in discount rate and unit price while revenue varied with a change in quantities sold and unit price. Regression analysis showed that a variation in the unit price of lettuce was stronger and negatively affected the quantity sold (R=0.91) than the influence the same independent variable on revenue earned (R=0.84). Based on the study results, hydroponics has the potential to act as a suitable alternative in vegetable production system and improve accessibility to vegetables across urban areas in a cost-effective manner. This will also assist in contributing to sustatinable develeopment goals; 3 (good health and wellbeing) and 11 (sustainable cities and communities). There is need to study the perfomance of other vegetables as well as various factors that can improve crop perfomance using the hydroponic system inorder to boost; crop yield, adoption of the system and hence vegetable accessibility and food security. Policy makers and governments should put more efforts in training farming communities about hydroponics.Item Molecular Diversity of Bacteria from a Municipal Dumpsite: Implications to Public Health(The Nelson Mandela African Institution of Science and Technology, 2016) Mwaikono, Kilaza SamsonDespite known risks of inappropriate disposal of solid wastes; most cities in developing countries dispose waste in open dumpsite where humans, animals and microbes interact. This study was done in Arusha municipal dumpsite, Tanzania to investigate the abundance and diversity of bacteria, compare the faecal microbiota of pigs scavenging on dumpsite and indoor reared pigs, and also determine the resistance profile of enteric bacteria from the dumpsite. Domestic wastes, solid biomedical wastes, sludge from the river near the dumpsite and faecal materials of pigs were sampled. Total DNA was extracted and the variable region four (v4) of the 16S rRNA gene was sequenced using high throughput Illumina MiSeq platform. The quality control of sequences and the statistical analyses was performed using Mothur platform. A total of 8,469,294 quality sequences were generated. The mean of bacterial species per sample was 8,243. Diversity was high with an average InvSimpson index of 44.2. Thirty-five bacterial phyla dominated by Firmicutes (38%), Proteobacteria (35%), Bacteroidetes (13%) and Actinobacteria (3%) were found. Overall, 76,862 operational taxonomic units (OTUs) dominated by Acinetobacter (12.1%), Clostridium sensu stricto (4.8%), Proteinclasticum and Lactobacillus (each 3.4%), Enterococcus (2.9%) and Escherichia/Shigella (1.7%) were revealed. There was a significant difference in faecal microbiota between scavenging and indoor reared pigs. Pathogenic genera like Brucella, Rickettsia and Listeria were exclusive to scavenging pigs. In solid biomedical waste, 36.2% of OTUs were related to dehalogenation, 11.6% degraders of aromatic hydrocarbons, 8.5% chlorophenol degradation and Atrazine metabolism 8.3%, and bacteria related to pathogens were 34%. Escherichia/ Shigella, Bacilli and Proteiniclasticum were predominant enteric bacteria. Some bacteria in scavenging pigs had 99% sequence similarity to pathogenic Escherichia furgosonii, Shigella sonnei, Enterococcus faecium and Escherichia coli O154:H4. Over 50% of the isolates were multidrug resistant. The study provides a comprehensive report on diversity of bacteria in Arusha municipal dumpsite. The high species richness shows the complexity of this man-made ecosystem, and calls for further research to assess for a link between human diseases and the dumpsite. This would provide insight into proper disposal of the waste, as well as, limit the risks to human health associated with the dumpsites.