Faculty of Applied Sciences
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Item The unseen breeding ground for pathogens : a study on the spectrum and awareness of microorganisms on smartphones of university students in South Africa, Kwa-Zulu Natal(2023-11-20) Kuarlal, Nikyle; Ndlovu, Thandie Sylph; Prakaschandra, Dorcas RosaleyBackground: Smartphone use has increased exponentially, having formed an integral part of the COVID-19 pandemic era, especially in the academic arena. It has been established that fomites can harbour potentially pathogenic microorganisms, which pose health risks to humans, particularly to the immunocompromised. The purpose of this study was to determine which microorganisms were harboured on the surfaces of smartphones, document the device sanitisation and hand hygiene habits of students within a university cohort, and determine associations of these habits with microorganism colonisation on smartphones. Methodology: This study prospectively sampled 168 randomly selected students from different departments at the Durban University of Technology (DUT). After informed consent, a swab sample from each participant’s smartphone was collected and transported to the microbiology laboratory for culture following standard microbiological guidelines. Participants were also asked about device sanitisation and their awareness of smartphones harbouring microorganisms. IBM Statistical Package for Social Sciences (SPSS) Statistics V.27 was used for data analysis with the use of descriptive statistics, Pearson chi-square and Pearson’s correlation tests. Results: From the 168 participants, microorganisms were detected in 113 (67.3%) samples, from which 20 different microorganisms were isolated. The majority of microorganisms (n = 17; 73.7%) were opportunistic pathogens. Out of the 168 questionnaire responses, only 36 (21.4%) study participants sanitised their smartphones despite 97 (57.7%) stating that they were aware of smartphones harbouring microorganisms. Conclusion: This study reports a high prevalence of microorganisms harboured on smartphones. The isolation of opportunistic pathogens, as well as the low frequency of smartphone sanitisation, raises a need for awareness of the contamination of smartphones and the potential risk of infection.Item Synthesis and structural elucidation of novel synthetic coumarin scaffolds for their potential pharmacological properties(2022-09) Laurel, Kabange Kasumbwe; Mohanlall, Viresh; Venugopala, Katharigatta NarayanaswamyTwo novel series of Schiff bases of 3-(2-aminothiazol-4-yl)-6,8-dichloro-2H-chromen-2- one (SVM 1-11) and 3-(2-aminothiazol-4-yl)-6-nitro-2H-chromen-2-one (SVN 1-11) were synthesized and confirmed by FT-IR, NMR, LC-MS and elemental analysis. The resulting compounds were evaluated for anti-tuberculosis activity using the micro Alamar blue assay (MABA) against susceptible strain H37Rv (ATCC25177) and multidrug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB). A computational method was also used to identify the molecular targets for these compounds. Larvicidal and insecticidal activity were evaluated against Anopheles arabiensis using the standard WHO larvicidal assay and cone bioassay methods. Anticancer activity was assessed using the MTT assay against human breast adenocarcinoma cells (MCF-7) and human epithelial lung adenocarcinoma cells (A549). The antioxidant and lipoxygenase inhibitory capacity was measured using the DPPH assay and Lipoxygenase inhibitory kit, respectively. The antimycobacterial efficacy of the synthesized SVM 1-11 showed that SVM 8 and SVM 10 were the most active compounds, with MIC values of 0.5 µg/mL against H37RvMTB and 8 µg/mL against MDR-MTB. Among the synthesized SVN 1-11, the most active compounds were SVN 3 and SVN 4, having MICs of 0.5 and 1 µg/mL against H37Rv-MTB, respectively, and 8 and 4 µg/mL against MDR-MTB. The docking study performed with the target enzymes DprE1and Pks13 indicated that the compounds had a high affinity for the druggable targets DprE1 and Pks13 enzymes of Mycobacterium tuberculosis compared to the reference standards rifampicin and isoniazid. The larvicidal and adulticidal tests revealed that compounds SVM 6 and SVM 9 were the most effective, with larvicidal mortality (100%) equal to the reference drug' Themephos; additionally, the above compounds exhibited significant adulticidal activity of 73.5±1.5 and 77.3±2.3%, respectively. Compounds SVN 6, 7, 8, and 9, on the other hand, were the most potent larvicidal and adulticidal, exhibiting 100% larvae mortality after 24 hours, and significant adulticidal activity. The anticancer activity study indicates that these compounds had a significant effect on MCF-7 cells. SVM 2, 4, 8 and 11 were the most effective with IC50 values ranging from 5.7 to 9.2 µg/mL. Compounds SVN 1, 2, 4, 9, 10, and 11, on the other hand, had a remarkable cytotoxicity effect on MCF-7, with IC50 range from 6.2-16.38 µg/mL. The caspase-Glo® kit test (Caspase 3/7, 8 and 9) was used to assess the mechanism involved in the anticancer activity of the selected active compounds against MCF-7. The results showed that the apoptosis generated by these compounds was triggered in part by the activation of caspase-3/7 and caspase-9, which may be the primary mechanism of apoptosis. The antioxidant results revealed that compounds SVM 3 and SVM 8 were the most potent, with a percentage scavenging capacity of 92.7±1.1 and 89.7±1.7%, respectively. Compounds SVN 5 and 9, on the other hand, were the most active, with a percentage scavenging capacity of 80.5±0.6 and 85.4±1.3%, respectively. The lipoxygenase inhibitory assay revealed that compounds SVM 3, 8, and 11 were the most potent LO inhibitors, with inhibitory capacity ranging from 60 to 67%. Compound SVN 11, on the other hand, was the most effective, with a percentage inhibitory capacity of 61.3±0.3%. Our results suggest that integrating different functional groups on the phenyl ring at the fourth position of the thiazole moiety, connected to the primary coumarin nucleus at the third position, contributed significantly to the biological activity of the compounds. These active compounds could be used as a scaffold for structural optimization to develop highly effective and selective antimycobacterial, anticancer, antioxidant, larvicidal, and adulticidal agents and promote further development of more efficient lipoxygenase inhibitors of novel structurally similar analogues.Item Human interpretable artificial intelligence applications for microbial-related diseases(2022-09) Espinoza, Josh L.; Singh, Suren; Nelson, Karen E.; Dupont, Christopher L.The human microbiome is a complex ecosystem that is influenced not only by host genetics but environmental stimuli. With advancements in next-generation sequencing (NGS) technologies, genomics and related meta-omics such as metagenomics, metatranscriptomics and metaproteomics have become increasingly accessible for researchers and clinicians to investigate microbial-related diseases. However, analysis of the outputs of “omics” technologies are often difficult due to variance introduced by biological complexity, batch effects from laboratory protocols/conditions, and the sensitivity/calibration of highly sensitive instruments. The biological complexity of “omics” presents a considerable analytical obstacle as most datasets contain hundreds of thousands to millions of unique features with unknown connections and nested hierarchies. In addition to this inherent complexity, the deluge of data generated from NGS technologies is fundamentally compositional, conveys only relative information, and because of this cannot be robustly analyzed using conventional statistical approaches. Furthermore, meta-omics datasets are typically sparse and the number of biological features often vastly exceeds the number of biological samples which can introduce anomalies in statistical analysis and the downstream findings if not addressed accordingly; a term dubbed as “the curse of dimensionality”. The complexity, compositionality, and dimensionality of “omics” datasets makes it challenging to derive clinical meaning and an understanding of the microbial system with respect to a host phenotype. Although, artificial intelligence and machine-learning methods have progressed substantially in recent years, their applications in domain sciences such as biology, and by extension “omics” technologies, have been limited in terms of human interpretability. In many machine-learning paradigms, interpretability is often sacrificed for analytical performance, or vice versa, but recently a domain-agnostic effort aims to develop explainable artificial intelligence algorithms that have both high modeling performance and human interpretability; a major goal of biomedical sciences. In this dissertation, I develop novel approaches in bridging biological science with machine learning methods at the vanguard of scientific development through the initiative of explainable artificial intelligence. The methods developed are validated on 3 datasets pertaining to microbial-related diseases including antibiotic resistance discovery, acute malnutrition in West African children, and caries pathology in Australian juvenile twins. The combination of methods developed are expected to provide the means for clinical researchers to overcome obstacles in interrogating the complex narratives that determine health and disease.Item Optimisation of edible oil effluent degredation by microorganisms(2003) Surujlal, Swastika; Bux, FaizalWater is a precious and very valuable resource. Water resource shortages are problems that are plaguing the world. There is therefore a high demand for tightening water quality standards for both potable water and waters in the environment. It is becoming a necessity to treat and reuse wastewaters, especially wastewaters from industries, as these waters are of concern due to their toxic effects on the environment. In South Africa one of the industries of major concern is that of the edible oil industry and there are over a dozen ofthese industries in South Africa alone. Each of these industries utilises approximately 1.75 million m3 of water and discharges approximately 0.61 million m3 to the sewer each year. This wastewater that is being released has very high organic, inorganic and fats, oils and greases loads. Depending on the type of refinery process conducted on the crude oil, the effluent quality and quantity varies on a day to day basis. The two types of refinery procedures are the physical refining, where water is used or chemical refining where caustic soda is used. The organic load ofthe untreated effluent can range from 1 100 to 8 990 mg COD/L, the oils and greases can range from 80 to 1 360 mg/L and the pH can range from 1.8 to 10.5.Item The isolation, identification and characterisation of the causative agent involved in the "paralysis syndrome" and the implementation of suitable control measures(1999) Govender, Mogambery Kisten; Kasan, Hamanth C."Paralysis syndrome" was first described by Dr M.J Versveld in 1993. The disease appeared to be confined to the Natal area with a few sporadic outbreaks in Gauteng, but none in the Cape region, nor in non-Rainbow flocks. The syndrome tended to re-appear on affected farms but not necessarily in the same houses. There was no correlation between affected flocks and their parent flock or hatchery identity (Maharaj, pers.comms.1994).Item Chemoprotective action of natural products on cultured human epithelial cells exposed to aflatoxin B1(2005) Reddy, Lalini; Odhav, BhartiPrevious studies indicate that a mutation in the non-oncogenic p53 gene is epidemiologically linked to human HCC (Ozturk, 1991; Chan et al., 2003). Hsu et al. (1991) found this link in Chinese, South African and Asian patients and Hollstein et al. (1993) found the same gene mutation in Taiwanese patients. The incidence of these aberrations is reported to be about 20- 50% in HCC’s (Kishimoto et al., 1997). There is sufficient evidence to indicate that carotenoids in addition to their well known antioxidant properties (Paiva and Russel, 1999), also affect intercellular communication, immune responses, neoplastic transformations and growth control, and cellular levels of enzymes that detoxify carcinogens (Zhang et al., 1991; Brockman et al., 1992; Pryor et al., 2000). To date studies carried out have used the rat (Foote et al., 1970; Gradelet et al., 1998) and the mule duckling model (Cheng et al., 2001) to show the protective effect of these carotenoids against AFB1 exposure. Of the well known carotenoids, lycopene and beta- carotene occur in abundance in fruits and vegetables and are safe for human consumption. Aflatoxin B1 frequently induces mutations of the p53 gene which is linked to HCC. Although there is much evidence from epidemiological studies linking the beneficial aspects of carotenoids to the prevention of cancer, the cellular and molecular mechanisms need to be understood in order to implement large scale intervention strategies to prevent AFB1 induced carcinoma. The use of chemical or dietary interventions to alter the susceptibility of humans to the actions of carcinogens and to block, retard or reverse carcinogenesis is an emerging chemoprotective strategy for disease prevention (Abdulla and Gruber, 2000; Kensler et al., 2003; Bingham and Riboli, 2004). Chemoprotection by natural products involves maintaining cellular integrity, preventing DNA alterations, activation of p53 suppressor protein and apoptosis. The aim of this study was thus to investigate the cellular and molecular mechanisms by which beta-carotene and lycopene may prevent the AFB1-induced toxic changes in human hepatocytes. In order to achieve this aim, the following objectives were set out: i. To optimise an in vitro system for the evaluation of AFB1 damage to cultured hepatocytes. ii. To determine the biochemical protection offered by beta-carotene and lycopene to AFB1-exposed hepatocytes, by measuring the mitochondrial activity, cell viability and ROS levels using appropriate enzyme assays and flow cytometry. iii. To determine the cellular protection offered by beta-carotene and lycopene to AFB1-exposed hepatocytes, by studying the morphological changes at the structural and ultrastructural levels using phase contrast light and electron microscopy respectively. iv. To determine the molecular protection offered by beta-carotene and lycopene to AFB1-exposed hepatocytes, by detecting apoptotic bodies as genomic markers and measuring the levels of p53 protein and AFB1-N7-guanine adducts produced.