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Item type:Item, Multi-proxy constraints on the origin, dynamics, and geochemical evolution of soil inorganic carbon in semi-arid landscapes of Botswana(Botswana International University of Science and Technology(BIUST), 2026-08) Ebouel,Ferdinand Junior DinaSoil inorganic carbon (SIC) constitutes a major component of the terrestrial carbon pool, particularly in dryland environments where pedogenic carbonates dominate long-term carbon sequestration. Despite its diverse environmental and ecological importance, SIC remains largely underrepresented in global carbon budgets, a deficit compounded by a lack of research into its formation dynamics and role as a proxy for paleoenvironmental and climatic evolution. This thesis addresses the prominent theoretical and methodological gaps through a progressive, multi-scale investigation of SIC in the semi-arid landscapes of Botswana. Using pedological and sedimentological approaches, the study characterised SIC formation pathways across major landscape units by integrating morphological examinations, mineralogical analyses, major and trace element geochemistry, and stable isotopes (δ13C, δ 18O). The findings highlight a regional dominance of pedogenic carbonate accumulation, driven by the mobilisation of calcium ions within distinct hydrological and geological settings. In the Kalahari Basin, this process is driven by felsic rock weathering and local fluviolacustrine reworking of lithogenic materials. Two mechanisms operate simultaneously. Mobilised calcium may originate from the in-situ dissolution of pre-existing carbonates or from the upward movement of calciumenriched soil solutions through evapotranspiration. While on the Eastern Hardveld, calcium is primarily supplied by the weathering of silicate-rich basaltic rocks. The results highlight an insitu mobilisation mechanism linked to the weathering of basaltic rock fragments reworked into the soils, in addition to upward movement. Stable isotope of carbon (δ13C) and oxygen (δ18O) signatures in carbonates indicate persistent semi-arid conditions and C3-C4 mixed vegetation. Furthermore, REE fractionation patterns and negative cerium anomalies provide robust, independent constraints for distinguishing pedogenic from lithogenic signatures, overcoming limitations of major-element-based interpretations. Collectively, these results advance the geochemical understanding of SIC formation in underrepresented regions and provide a transferable methodological framework for investigating soil carbon dynamics. This work reduces critical uncertainties in the global carbon budget and establishes a transferable framework for tracing SIC formation across semi-arid environments.Item type:Item, Antibacterial activities of potential antibiotic-producing bacteria and indigenous plants against antibiotic-resistant bacteria(Botswana International University of Science and Technology (BIUST), 2025-07) Makale, Katlego P.P; Rahube, Teddie O; Rantong, Gaolathe; Makhzoum, AbdullahAntibiotic resistance is a significant global public health problem, intensified by anthropogenic activities. The resistance contributes to longer hospital stays, increased health care, and high death rates. Natural compounds from medicinal plants and bacteria are attractive alternatives for the development of novel antibiotics and ultimately combating antibiotic resistance. The study aimed to isolate, and screen crude plant extracts and bacteria for antibacterial properties. Selected test bacteria; Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Proteus mirabilis MN029 were used in the screening of antibacterial properties of selected plants and potential antibiotic-producing bacteria. Long-read PacBioⓇ HiFi technology was used to sequence Proteus mirabilis-MN029 and the strain was used as a model for multi-drug resistant bacteria in evaluating the antibacterial properties of plant crude extracts. The Proteus mirabilis-MN029 genome comprised of a single chromosome, 38.5% G+C content and 3,988,563 bps in length, acquired and chromosomally encoded antimicrobial resistance genotypes to clinically relevant antibiotics, virulence factors, drug targets and transporters. Potential antibiotic-producing bacteria were also isolated from soil and water samples, the isolates that inhibited at least four test bacteria were subjected to Gram staining, biochemical testing, and antibiotic susceptibility testing. Four promising antibiotic-producing bacteria were sequenced using short-read sequencing technology on the Illumina platform. The potential antibiotic-producing bacteria were identified as Paenibacillus elgii-KM_B45, Brevibacillus laterosporus-KM_C76, Paenibacillus oleatilyticus-KM_D13 and Paenibacillus oleatilyticus-KM_D46, their genomes revealed 23 biosynthetic gene clusters associated with antibacterial properties. Pterocarpus angolensis, Aloe zebrina and Aloe littoralis were also tested 1 for antibacterial effectiveness against the test bacteria. Maceration was used to extract plant crude extracts using solvents of different polarities. The primary screening was conducted using Kirby Bauer Disc diffusion, while microdilution assay was employed as a secondary screening for determining the minimum inhibitory concentration of the medicinal plants against the test bacteria. Among the three tested medicinal plants, P. angolensis inhibited most of the test bacteria compared to A. littoralis and A. zebirna. The highest activity was demonstrated at MIC of 0.075 mg/ml by A. littoralis and A. zebrina ethylacetate root extracts against S. aureus. The results of antibacterial activities associated with the selected bacteria and plants provide a great opportunity for further research, which will focus on the purification of the secondary metabolites for use in the development of new antibiotics.Item type:Item, Phytochemical and antioxidant analysis of Citrullus ecirrhosus seed: an in vitro and in silico evaluation towards atherosclerosis management(Botswana International University of Science and Technology (BIUST), 2025-04) Kambasiya, Walter; Masisi, Kabo; Makhzoum, AbdullahAtherosclerosis is an inflammatory condition of the arteries that contributes significantly to around 84.5% of all CVD mortality. It is distinguished by lipid accumulation in coronary arteries, which results in plaque development, reduced blood flow, and oxygen availability to various body tissues. This study therefore aimed at assessing phytochemicals of Citrullus ecirrhosus seed powder from three varieties, their antioxidant potential and predicting the binding mode of HMG-CoA reductase enzyme towards phyto-compounds using in silico studies as a drive towards atherosclerosis management. Secondary metabolites were extracted from Citrullus ecirrhosus seed powder using water, methanol, ethyl acetate, chloroform and hexane, and evaluated for total phenolic content (TPC) and total flavonoid content (TFC). The polar extracts (methanol and water) had higher phenolic and flavonoid content as compared to the moderate and non-polar seed powder extracts (P < 0.05). The methanolic and water extracts also showed higher (P < 0.05) free radical scavenging capacity as compared to the other moderate and non-polar solvent extracts in the DPPH and ABTS assays. This showed that the seed powder extract was rich in polar phytochemicals as compared to the non-polar. Identification of secondary metabolites of the extract was done using GC-MS. From a range of phytochemicals identified, 19 of those had reported antioxidant activities. These are Hexadecanoic acid; methyl ester (methyl palmitate); n-Hexadecanoic acid; Phenol, 2,4-bis(1,1-dimethylethyl); γ-Tocopherol; Hydroxylamine 5-Hydroxymethylfurfural; ester; O-decyl; Vanillin 13-Octadecenoic lactoside; acid methyl Octadecanoic ester; acid; 9,10-Secocholesta-5,7,10(19)-triene-3,24,25-triol, (3β,5Z,7E); cis-Vaccenic acid; Pentanoic acid, octyl 3-Dodecene, (Z); 1-Heptatriacotano; Nonadecane; 2-Piperidinone, N-[4-bromo-n-butyl]; Heptacosane; Stigmasterol; 2-Methoxy-4-vinylphenol. The molecular interaction between HMG-CoA reductase enzyme, which is significant in cholesterol regulation, was studied against the 19 phytoconstituents from the seed powder extracts in silico. The phytoconstituents with high binding affinity within the range of that for the statins used were Vanillin lactoside, 9,10-secocholesta-5,7,10(19)-triene-3,24,25-triol, stigmasterol, gamma-Tocopherol and Phenol, 2,4-bis(1,1-dimethylethyl)-. Their binding affinities ranged from -8.2 to -6.3 kcal/mol. Vanillin lactoside showed the highest binding affinity of -8.2 kcal/mol and the interactions between the compound and the protein were predicted to be through conventional hydrogen bond, carbon hydrogen bond, Pi-Cation, Pi-Alkyl and unfavorable donor-donor interactions. This study thus showed that the Citrullus eccirhosus seeds have phytochemicals with antioxidant activity and some phytochemicals having a binding mode towards the HMG-CoA reductase enzyme in silico. However, there is also need to carry out wet lab analysis so as to confirm the ability of the seed powder in reducing the atherosclerotic lesion in atherosclerosis induced albino wistar rats.Item type:Item, Immortalization of primary lamb kidney cells towards a continuous cell line for propagation of foot and mouth disease virus(Botswana International University of Science and Technology (BIUST), 2025-07) Gaboiphiwe, Kitsiso; Lebani, Kebaneilwe; Masisi, Kabo; Fana, E.MFoot and mouth disease (FMD) is a highly contagious disease of great economic importance. The disease is caused by foot and mouth disease virus (FMDV). Diagnosis of FMD is done through tests such as virus isolation (VI), enzyme linked immunosorbent assay (ELISA), virus neutralisation tests (VNT) and polymerase chain reaction (PCR) platforms. Tests such as VI and VNT require the use of cells that are susceptible to infection with FMDV. Cells that can be used for FMDV culture include primary cells and cell lines developed for diagnostic applications. Cells such as primary lamb kidney cells have been shown to be very sensitive to infection with FMDV, but the cells are short lived, laborious to prepare, and give variable results due to the use of different batches. Notwithstanding, the sensitivity of primary lamb kidney cells to infection by FMDV can be taken advantage of and developed into a cell line. Primary lamb kidneys cells’ lifespan can be increased through exogenous introduction of telomerase reverse transcriptase (TERT). In this study, transduction was conducted on primary lamb kidney cells at 80% confluency using recombinant lentivirus to over express TERT. The lentivirus construct included puromycin antibiotic resistance, thus, the cells were subjected to antibiotic selection, and surviving cells were expanded further. The over expression of TERT was confirmed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) using a comparative ΔΔct method. The differences in the cycle thresholds for detection of TERT between primary cells and transduced cells showed increased expression of TERT in transduced cells. This increased expression however waned with increased cell passages. Encouragingly, the transduced cells were able to maintain similar morphology to primary cells over successive passages. The growth rate results also showed that primary cells’ growth regressed with progressive passaging as that of transduced cells increased. Analysis of TCID50/mL results for SAT and O serotypes of FMDV demonstrated no significant differences between primary and transduced cells. Virus isolation of SAT and O serotypes of FMDV gave similar time intervals to reach 100% cytopathic effect. These results demonstrate promise that the transduced cells could be used as a possible replacement for primary lamb kidney cells. Future work however must determine the extent of passaging that can be undertaken on transduced cells before there are notable changes to properties of the transduced cells. The transduced cells would also need to be validated using a broader range of virus serotypes and strain.