ResearchSpace

Communities in ResearchSpace

Welcome to ResearchSpace, the institutional repository of the CSIR. ResearchSpace is an open access electronic archive collecting, preserving and distributing scholarly digital materials created by the CSIR.

Recent Submissions

Item

Plant-derived natural products and their nano transformation: A sustainable option towards desert locust infestations

(2024-11) Mangundu, P; Makaudi, R; Paumo, HK; Ramalapa, Bathabile E; Tshweu, Lesego L; Raleie, N; Katata-Seru, L

The desert locust has been recognized as the most devastating migratory pest in the world. Swarms of this pest have been threatening vast regions of pastures and crops in Africa, Middle East, and South Asia. The biological management of expanding swarms has become a strategy of particular interest due to environmental awareness and economic issues associated with chemical pesticides. The present review aims to explore the latest updates and information about pesticidal plants that are distributed across Africa. Searches on Web of Science, Google Scholar, PubMed, and Scopus databases from 2013–2024 revealed a total of 22 plant species probed for insecticidal activities against desert locusts. The formulation, active ingredients, and biological effects of essential oils and other extracts from these plants are presented. Despite the promising antiwww.chemistryopen.org [a] [a] Bathabile Ramalapa, [b] insecticidal effects of the plant extracts and compounds, issues related to their solubility and instability under environmental conditions have been observed. To address such major quality defects, methods for the encapsulation of plant natural products within nanostructures are detailed. Given the presence of bioactive compounds with nucleophiles bearing functional groups, the reported plant extracts have been exploited to fabricate metal nanoparticles with inherent insecticidal activities. In this paper, a holistic overview of prepared phytochemical-coated metal nanopesticides is also presented. In summary, this study offers insights into the integration of nanoformulated natural resources as a more sustainable option to control desert locust invasions.

Item

Enterobacter spp. isolates from an underground coal mine reveal ligninolytic activity

(2024-10) Rammala, BJ; Ramchuran, Santosh O; Chunilall, Viren; Zhou, N

Lignin, the second most abundant renewable carbon source on earth, holds significant potential for producing biobased specialty chemicals. However, its complex, highly branched structure, consisting of phenylpropanoic units and strong carbon-carbon and ether bonds, makes it highly resistant to depolymerisation. This recalcitrancy highlights the need to search for robust lignin-degrading microorganisms with potential for use as industrial strains. Bioprospecting for microorganisms from lignin-rich niches is an attractive approach among others. Here, we explored the ligninolytic potential of bacteria isolated from a lignin-rich underground coalmine, the Morupule Coal Mine, in Botswana. Using a culture-dependent approach, we screened for the presence of bacteria that could grow on 2.5% kraft lignin-supplemented media and identified them using 16 S rRNA sequencing. The potential ligninolytic isolates were evaluated for their ability to tolerate industry-associated stressors. We report the isolation of twelve isolates with ligninolytic abilities. Of these, 25% (3) isolates exhibited varying robust ligninolytic ability and tolerance to various industrial stressors. The molecular identification revealed that the isolates belonged to the Enterobacter genus. Two of three isolates had a 16 S rRNA sequence lower than the identity threshold indicating potentially novel species pending further taxonomic review. ATR-FTIR analysis revealed the ligninolytic properties of the isolates by demonstrating structural alterations in lignin, indicating potential KL degradation, while Py-GC/ MS identified the resulting biochemicals. These isolates produced chemicals of diverse functional groups and monomers as revealed by both methods. The use of coalmine-associated ligninolytic bacteria in biorefineries has potential.

Item

Proteomic analysis identifies dysregulated proteins in albuminuria: A South African pilot study

(2024-08) Khoza, S; George, JA; Naicker, Previn; Stoychev , SH; Fabian, J; Govender, Ireshyn S

Albuminuria may precede decreases in the glomerular filtration rate (GFR) and both tests are insensitive predictors of early stages of kidney disease. Our aim was to characterise the urinary proteome in black African individuals with albuminuria and well-preserved GFR from South Africa. This case-controlled study compared the urinary proteomes of 52 normoalbuminuric (urine albumin: creatinine ratio (uACR) < 3 mg/mmol) and 56 albuminuric (uACR ≥ 3 mg/mmol) adults of black African ethnicity. Urine proteins were precipitated, reduced, alkylated, digested, and analysed using an Evosep One LC (Evosep Biosystems, Odense, Denmark) coupled to a Sciex 5600 Triple-TOF (Sciex, Framingham, MA, USA) in data-independent acquisition mode. The data were searched on SpectronautTM 15. Differentially abundant proteins (DAPs) were filtered to include those with a ≥2.25-fold change and a false discovery rate ≤ 1%. Receiver–operating characteristic curves were used to assess the discriminating abilities of proteins of interest. Pathway analysis was performed using Enrichr software. As expected, the albuminuric group had higher uACR (7.9 vs. 0.55 mg/mmol, p < 0.001). The median eGFR (mL/min/1.73 m2) showed no difference between the groups (111 vs. 114, p = 0.707). We identified 80 DAPs in the albuminuria group compared to the normoalbuminuria group, of which 59 proteins were increased while 21 proteins were decreased in abundance. We found 12 urinary proteins with an AUC > 0.8 and a p < 0.001 in the multivariate analysis. Furthermore, an 80-protein model was developed that showed a high AUC ˃ 0.907 and a predictive accuracy of 91.3% between the two groups. Pathway analysis found that the DAPs were involved in insulin growth factor (IGF) functions, innate immunity, platelet degranulation, and extracellular matrix organization. In albuminuric individuals with a well-preserved eGFR, pathways involved in preventing the release and uptake of IGF by insulin growth factor binding protein were significantly enriched. These proteins are indicative of a homeostatic imbalance in a variety of cellular processes underlying renal dysfunction and are implicated in chronic kidney disease.

Item

Comparative evaluation of the power-to-methanol process configurations and assessment of process flexibility

(2024-07) Mbatha, Siphesihle; Cui, X; Panah, PG; Thomas, S; Parkhomenko, K; Roger, A-C; Louis, B; Everson, R; Debiagi, P; Musyoka, N; Langmi, H

This paper compares different power-to-methanol process configurations encompassing the electrolyser, adiabatic reactor(s) and methanol purification configurations. Twelve different power-to-methanol configurations based on direct CO2 hydrogenation with H2 derived from H2O-electrolysis were modelled, compared, and analysed. A high temperature solid oxide electrolyser is used for hydrogen production. A fixed bed reactor is used for methanol synthesis. The aim of the paper is to give detailed comparison of the process layouts under similar conditions and select the best performing process configuration considering the overall methanol production, carbon conversion, flexibility, and energy efficiency. ASPEN PLUS® V11 is used for flowsheet modelling and the system architectures considered are the open loop systems where methanol is produced at 100 kton per annum and sold to commercial wholesale market as the final purified commodity. Further optimization requirements are established as targets for future work. Three options of power-to-methanol configuration with methanol synthesis from CO2 hydrogenation are proposed and further evaluated considering process flexibility. From the evaluation, the series–series based configuration with three adiabatic reactors in series performed better in most parameters including the flexible load dependent energy efficiency.

Item

Settlement-level economic performance as a factor influencing working-age population migration in South Africa

(2024-12) Arnold, Kathryn A; Le Roux, Alize; Smit, JL; Mans, Gerbrand G

South African towns and cities face substantial challenges, owing largely to the pace of economic growth to date and continued migration of people from rural areas. The widely accepted push–pull theory of migration assumes that migration is a functional and inevitable outcome of spatial inequality. Economic drivers are frequently used to explain population movements in South Africa, given that the country’s biggest socio-economic challenges include high unemployment, stark inequality and persistent poverty. This study empirically investigates the theoretical perspective of the push–pull model from an economic and settlement-based standpoint. It establishes a settlement-level perspective of the relationship between economic performance and working-age population change in South Africa between the 2001 and 2011 Censuses. Fine-resolution downscaled economic and population datasets are used, applying spatial GIS-based methods and techniques, together with statistical correlation analyses, to explore and quantify the relationship. Population change in the working-age population is found to have a positive statistically significant association with economic performance at settlement level. The relationship is multifaceted, given the complexity of South Africa’s economic and development landscape, with considerable variability between different economically profiled settlement types, and different demographic groups based on age, gender, employment status and skills level.