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Extraction and identification of endophytes for skin health
(2026) Mahlangu, Siphiwe Godfrey; Mokwatlo, Sekgetho Charles; Zulu, Nodumo; Tai, Siew
The health crisis of multidrug microbial resistance is responsible for approximately 700 000 deaths annually, worldwide. Interest in exploring ancient treatment methods to develop novel therapeutic strategies against multidrug-resistant (MDR) pathogens has increased in recent years. The ongoing increase in the number of infectious diseases exacerbated by antimicrobial resistance has intensified the need for novel, organic, and potent antimicrobial agents. In addition, antioxidant compounds are valuable in drug discovery owing to their defensive effects against oxidative stress, potentially treating various ailments including skin diseases and infections. Medicinal plants produce a plethora of bioactive compounds with antimicrobial and antioxidant properties, which play critical roles in drug development. Centella asiatica (L) Urban and Gunnera perpensa L are multipurpose medicinal plants indigenous to the Western Cape Province of South Africa. These medicinal plants treat inflammation, burns, ulcers, wounds, postoperative hypertrophic scars, eczema, and cough. However, the extensive use of medicinal plants for drug development can result in deforestation, potentially leading to the extinction of plant species. This can be prevented by using endophytes, as only a small portion of the plant sample is required for extraction. Thus, endophytes (endo-symbiotic bacteria and fungi) reside in host plants. Endophytes stimulate the host plant defence system and contribute to their medicinal properties. Endophytes sometimes produce compounds similar to those produced by the host plants, making them promising candidates for drug development. Hence, these compounds have proven valuable resources as they may have significant untapped potential to eradicate multidrug-resistant infections and oxidative stress in humans. In this study, fresh healthy plant samples were collected and 31 endophytic bacteria were isolated from surface-sterilized Centella asiatica leaves and Gunnera perpensa rhizomes, with 20 bacterial endophytes isolated from C. asiatica leaves and 11 endophytic bacteria isolated from G. perpensa rhizomes. C. asiatica isolates were identified as Pseudomonas sp. strain (SGM1, SGM2, SGM3, SGM4, SGM5, SGM6, SGM7), Novosphingobium sp. strain SGM8, Pseudomonas sp. strain (SGM9, SGM10), Chryseobacterium sp. strain SGM11, Enterobacter sp. strain SGM12, Enterobacter sp. strain SGM13, Pseudomonas sp. strain SGM14, Enterobacter sp. strain SGM15, Enterobacter sp. strain SGM16, Agrobacterium sp. strain SGM17, Pantoea sp. strain SGM18, Paraburkholderia sp. strain SGM19, and Pseudomonas sp. strain SGM20. Herbaspirillum sp. (GP-SGM1, GP-SGM2, GP-SGM3, GP-SGM11), Pseudomonas sp. (GP-SGM4 and GP-SGM5), and Novosphingobium sp. GP-SGM6, Chryseobacterium sp. GP-SGM7, Labedella sp. GP-SGM8, Brevibacterium sp. GP-SGM9, and Pseudomonas sp. GP-SGM10 were isolated from G. perpensa rhizomes and characterized by scanning electron microscopy (SEM). The growth kinetics of the 31 endophytic bacteria were evaluated using the specific maximum growth rate (µmax) and optical density (OD) values on 12-well microtiter plates. Standard bacterial growth trends were observed for C. asiatica strains, with the exception of Enterobacter sp. strain SGM15 (0.03 ± 0.02 hr-1) which portrayed slower cell growth, while Pseudomonas sp. strain SGM6 (0.27 ± 0.16 hr-1) displaying the highest µmax, followed by Enterobacter sp. strain SGM16 (0.25 ± 0.32 hr-1). Additionally, Pseudomonas sp. strain SGM3 exhibited the highest maximum OD (6.74 ± 0.14), while the lowest maximum OD was recorded for Novosphingobium sp. strain SGM8 (0.14 ± 0.06). G. perpensa strains growth trends revealed that Chryseobacterium sp. GP-SGM7 portrayed the highest µmax and OD values of 0.33 ± 0.01 hr−1 and 4.20 ± 0.04 while Herbaspirillum sp. GP-SGM11 portrayed noticeably slower growth (0.12 ± 0.05 hr−1) and least microbial growth (1.50 ± 0.00). The antibacterial activity was evaluated using the disc diffusion method against five pathogenic bacteria: Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. It was observed that B. cereus, S. aureus, K. pneumoniae, and P. aeruginosa were more susceptible to the antibacterial metabolites from most endophytic isolates from C. asiatica and G. perpensa isolates. All 31 endophytic crude metabolites were ineffective against E. coli. Pseudomonas sp. strain SGM2 from C. asiatica, and Chryseobacterium sp. GP-SGM7 from G. perpensa exhibited significant antibacterial activity. The DPPH and FRAP assays demonstrated that all C. asiatica and G. perpensa endophytic crude metabolites portrayed strong antioxidant activity in a dose-dependent manner with Pseudomonas sp. strain SGM2 displaying the greatest DPPH (88.09 ± 0.73 %) and Chryseobacterium sp. strain SGM11 showing the highest antioxidant activity in the FRAP assay (0.72 ± 0.01) of the C. asiatica endophytic strains and Chryseobacterium sp. strain GP-SGM7 and Pseudomonas sp. strain GP-SGM10 showed the highest scavenging activity (73.86 ± 1.01 % and 73.66 ± 1.68 %, respectively); greater reducing power of 0.54 ± 0.01 was also exhibited by Chryseobacterium sp. strain GP-SGM7 demonstrating the greatest antioxidant properties for G. perpensa strains. Pseudomonas sp. strain SGM2 of C. asiatica and Chryseobacterium sp. GP-SGM7 of G. perpensa were chosen as the isolates of interest for further alteration of cultivation parameters to maximize growth yields and metabolite production. The effects of different temperatures (23, 30, and 37°C) and glucose feed (0, 2, 4, and 8 g/L) on the growth patterns and production of antibacterial and antioxidant metabolites in Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GP-SGM7 were grown in 2 L shake flasks. Cultivation of Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GP-SGM7 at 30°C with 0 g/L glucose appeared to increase the microbial growth, as the highest maximum OD was observed under these conditions. However, increasing the temperature to 37°C with or without glucose supplementation resulted in a decrease in the microbial yield. However, at 37°C with 0 g/L glucose, µmax increased in Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GPSGM7 was observed at 23 and 30°C in the presence of 0 g/L glucose. The antibacterial and antioxidant properties under these conditions revealed significant inhibition against S. aureus at 30°C (2, 4, and 8 g/L) and at 30°C with 0 g/L glucose, significant inhibition was observed against four pathogenic strains B. cereus, S. aureus, K. pneumoniae, and P. aeruginosa. No inhibition was observed for E. coli, and endophytic crude metabolites cultivated at 23 and 37°C (0, 2, 4, and 8 g/L) were not effective against all test strains. In addition, 30°C (0 g/L glucose) resulted in greater DPPH scavenging free radical activity for Pseudomonas sp. strain SGM2 (88.09 ± 0.73 %) at 20 mg/L concentration and highest DPPH for Chryseobacterium sp. GPSGM7 was observed at 30°C (0 and 4 g/L), with scavenging activity of 73.86 ± 1.01 % and 80.97 ± 0.43 %, respectively. Furthermore, Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GP-SGM7 showed a significantly higher FRAP in the presence of 4 g/L glucose at 30°C. The absence of glucose and suboptimal and high temperatures resulted in decreased FRAP values. Optimum conditions for improved microbial yields and antibacterial and antioxidant production by Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GP-SGM7 was grown at 30°C with 0 g/L glucose and applied to a 0.5 L Sixfor bioreactor runs. The effect of altering fermentation conditions on endophytes of interest for increased growth yields and metabolite production in a controlled environment was then investigated in a 0.5 L Sixfor bioreactor. This included testing at various pH levels (5, 6, and 7), agitation speeds (190, 250, and 500 rpm) and aeration rates (1 and 3 vvm). To validate the shake flask cultivation, an additional run was performed with 3 g/L glucose to assess the growth yields and efficacy of the metabolites produced under the selected parameters. When all changes were incorporated into the bioreactor fermentation conditions, a slight improvement was observed in biomass and antioxidant production, owing to the better agitation and oxygen availability experienced in the bioreactor. However, no antibacterial or antibiotic metabolites were produced under the tested conditions owing to the lack of antibacterial activity. The bioreactor samples were analyzed for glucose consumption trends using high-performance liquid chromatography (HPLC), and glucose utilization was detected under fermentation conditions of pH 7 – 500 rpm – 3 vvm (3 g/L glucose feed) with glucose depletion at 24 h. No residual glucose was detected under the other tested cultivation conditions. Moreover, comprehensive metabolite profiling of the crude secondary metabolites of Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GP-SGM7 was analyzed using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Metabolite profiling of Pseudomonas sp. strain SGM2 and Chryseobacterium sp. GP-SGM7 under various reactor fermentation conditions yielded 86 and 93 metabolites, respectively, with distinct metabolites detected during fermentation at pH 7 – 500 rpm and 3 vvm (3 g/L glucose feed). Agitation speed, aeration rate, and pH are key parameters in endophyte biomass production. Although neutral pH, high agitation and aeration, and the addition of the carbon source glucose were conducive to endophytic growth and yielded the highest biomass, they did not necessarily facilitate antibiotic/antimicrobial production.
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Open Access
Exploration of skills development programmes contributing towards youth employment: A case study of the Waves of Change and Not in Education, Employment, or Training Programmes in Cape Town, South Africa
(2026) Mahamba-Sithole, Langalakhe; Hoosain, Shanaaz
South Africa has been affected by a youth unemployment crisis, with many young people struggling to enter the workforce. Non-governmental organisations and civil society have created initiatives to provide youth with life skills and work readiness training. This study sought to explore skills development interventions targeting youth employment by conducting a case study of the Waves of Change and NEETs programmes in Cape Town. This study was based on a qualitative, exploratory, descriptive research design, and therefore, interviews were conducted with twelve programme graduates who participated in the past three years. The study's key findings revealed that the programmes made young people more employable. However, their graduates needed to take personal responsibility to complete the programmes and find work. The classes and activities run by the programmes worked to improve the interpersonal skills and professionalism of the participants. The interactions with the facilitators and the services provided by the programmes were also vital for making the participants more employable. Barriers to employment were noted to include the lack of work experience, documentation, and certification requirements, as well as the locations of the companies. The key recommendations are that the government allocates resources to running similar youth skills development programmes across South Africa. In addition, the government should incentivise companies to run internships and trainee programs so that young people can acquire experience. Further research should explore company recruiters' perceptions of unemployed youth and requirements for job seekers.
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Open Access
KGANG KGOLO: The thing that matters
(2026) Magano, Clarah; Mahashe, George; Monoa, Thabang
KGANG KGOLO: The Thing That Matters examines the intersections of identity, memory, and archival practice in Southern Africa, reflecting on personal and collective histories. Using visual culture, storytelling, and decolonial frameworks, the study interrogates how identity is shaped, contested, and represented through state apparatuses such as identity documents, letters, and visual archives. Central to the study, the concept of KGANG KGOLO draws on African womanism and existential phenomenology, offering a lens to explore the experiences of marginalised groups. Through the narratives of the Barokologadi ba ga Maotwe in Melorane and Pitsedisulejang, and my grandmother, Mme Lena Motletlwa “MmaSpech” Mogotsi, this framework examines the layered intersections of personal and political identity, highlighting forced removals and land dispossession in the 1950s, including the displacement from Melorane to Pitsedisulejang/Madikwe Game Reserve. Using autoethnography, critical fabulation, and oral histories, the study reconstructs fragmented familial and ancestral memories, emphasizing Setswana's role in preserving these narratives. Engaging with scholars such as Uhuru Phalafala, NoViolet Bulawayo and Saidiya Hartman, it critiques the erasure of African languages in academia and advocates for their reintegration as valid intellectual frameworks. This linguistic marginalisation is positioned as both a site of resistance and a tool for decolonial memory-making, enabling communities to reclaim histories and epistemologies from colonial frameworks. The research also explores the relationship between state-issued identity documents: passbooks, reference books, and biometric IDs, and personal autonomy, showing how these tools both restricted and facilitated movement and citizenship. MmaSpech's experiences under apartheid, alongside ongoing challenges with contemporary identification systems, reveal the long-standing role of state surveillance in shaping Black identity, paralleling these bureaucratic practices with colonial and apartheid-era visual culture. By combining mainane, art history, sociology, anthropology, and political theory, KGANG KGOLO critiques institutional frameworks that perpetuate exclusion. It advocates for a re-evaluation of archives, integrating African languages and oral histories to reshape collective memory and confront the erasure of Black South African histories. The study foregrounds African women's experiences, such as MmaSpech's, highlighting their resilience, agency, and role in cultural survival amid systemic erasure. Ultimately, the study positions archives: visual, textual, and oral, as dynamic, contested spaces. The analysis of photographs, documents, and stories highlights ongoing struggles for land, identity, and belonging in post-apartheid South Africa, honoring marginalized personal histories and asserting African epistemologies as central to reimagining Southern African identities in a postcolonial context.
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Open Access
Systematics and diversification of the genus Aspalathus (Crotalarieae, Leguminosae)
(2026) Madika, Lydia Khumo; Muasya, Muthama; Zhigila, DA; Stirton, CH; Sebola, RJ
The genus Aspalathus L. (Leguminosae: Crotalarieae) exemplifies many of the traits associated with Cape radiations. With nearly 300 described species, and likely many more yet undescribed, Aspalathus is the second-largest genus within the Cape Floristic Region (CFR) and comprises one of the most taxonomically complex groups in the fynbos. Approximately 98 percent of its species are endemic to the region, and many display striking morphological adaptations to their respective microhabitats, including varied leaf structures, spinescence, flower pigmentation, and fire response strategies. Species of Aspalathus are often adapted to disturbance, especially wildfire, with many exhibiting reseeder life forms—a strategy that includes rapid post-fire germination and growth. Furthermore, like many legumes, they contribute to ecosystem functioning through symbiotic nitrogen fixation, thus playing a critical role in nutrient cycling. Beyond its ecological prominence, the genus has substantial economic relevance through Aspalathus linearis (Burm.f.) R.Dahlgren, the plant used to produce rooibos tea, a globally traded herbal infusion that supports an entire agricultural industry in South Africa. Taxonomically, the genus has posed longstanding challenges. The foundational classification was laid down over 40 years ago by botanist Rolf Dahlgren. Although pioneering, Dahlgren's work preceded the advent of molecular systematics, which now provide much higher resolution tools for inferring evolutionary relationships. Recent decades have seen the discovery and description of over 20 new species of Aspalathus following Dahlgren's treatment. However, efforts to reconstruct the evolutionary tree of Aspalathus using standard DNA barcodes have yielded low-resolution phylogenies, often failing to resolve deeper nodes. These limitations underscore the urgent need for genomic-scale datasets and a reappraisal of existing taxonomic frameworks. This thesis is organized around three core aims: (1) to resolve long-standing phylogenetic uncertainty within Aspalathus, and to test the monophyly of the genus and utility of taxonomic characters, using Sanger sequencing data; (2) to infer backbone topology and infrageneric classification, and to investigate determinants of diversification patterns, using phylogenomic data; and (3) to revise the taxonomy of Aspalathus subgen. Sericea, a morphologically and ecologically distinct subgroup, using wealth of specimens and morphometric analyses. The study is structured into three data chapters aligned with these aims, preceded by a general introduction (Chapter 1) and concluded with a synthesis (Chapter 5) that integrates key findings. Chapter 2 investigates the evolutionary cohesiveness of the genus Aspalathus using Sanger sequencing of four widely used genetic markers: ETS, ITS, matK, and trnS–trnG. A central question was whether Aspalathus, as currently circumscribed, forms a monophyletic group. Phylogenetic analyses, sampling 137 taxa and data analysed using Bayesian methods, produced a polytomy within the Aspalathus clade. Despite the low resolution, two major clades emerged within the polytomy, each showing a closer relationship to the clade containing the two genera Wiborgia Kuntze and Wiborgiella Boatwr. & B.-E.van Wyk, thus indicating that the genus Aspalathus, as traditionally defined, may not be monophyletic. Morphological assessments support this molecular signal: the two clades differ in several key traits, including leaf morphology, presence or absence of petioles, and leaflet shape, reinforcing the hypothesis of a deep evolutionary divergence within the genus. To overcome the limitations of low-resolution Sanger data, Chapter 3 employs the Angiosperms353 target capture sequencing, a cutting-edge phylogenomic method that samples hundreds of genes across the nuclear genome. This broader and more detailed dataset enables the construction of a well-resolved backbone phylogeny for the genus and confirms Aspalathus as being monophyletic. Analyses recover two strongly supported major clades in Aspalathus, designated here as Clade A and Clade B. Clade A includes the majority of species formerly assigned to Sericeae, while Clade B contains the remainder of the genus and is resolved into eight well-supported subclades. These subclades integrate multiple of Dahlgren's traditional groups: Subclade 1 unites Laterales (group 34), Calcicolae (33), Niveae (24), and two species of Pingues (22); Subclade 2 encompass Pingues (22); Subclade 3 links Digitifoliae (31) with the monotypic Vermiculatae; Subclades 4 and 5 together encompass Teretilobae (32), though resolved into two distinct molecular lineages; Subclade 6 is taxonomically complex and polyphyletic, including elements of Callosae (17), Carnosae (18), Cephalanthae (3), Crotalariiformes (4), Gigantes (15), and some Sericeae (1); Subclade 7 comprises the largest radiation, subdivided into Subclade 7A—which includes Pedunculares (6), Borboniae (7), Filicaules (8), Rostratae (9), Rubescentes (10), Adnates (11), Lepthanthae (12), Ternatae (13), Purpureae (14), and two Pingues species (22)—and Subclade 7B, which corresponds to the morphologically cohesive Terminales (29); and Subclade 8 unites Sulphureae (19) with Pachycarpae (21). The depth of divergence and the congruence between molecular and morphological data provide compelling evidence for a taxonomic reclassification. Consequently, this study formally proposes the division of the genus into two subgenera: Aspalathus subgen. Aspalathus and Aspalathus subgen. Sericea. This infrageneric classification confirms both evolutionary history and morphological distinctiveness. Divergence dating indicates that the crown age of Aspalathus is approximately 14.6 million years, with subsequent rapid radiation during the Miocene, coinciding with the expansion and ecological specialization of the fynbos biome. Chapter 4 presents a comprehensive taxonomic revision of Aspalathus subgen. Sericea (Clade A), with the overarching aim of clarifying species and subspecies boundaries, standardizing nomenclature, and providing an updated framework for identification and conservation assessment. The revision is based on extensive herbarium material, verified field observations, and quantitative morphometric analyses, with selected micromorphological traits examined in detail. Data on habit, vegetative and floral morphology, life history traits, and habitat preferences were compiled and analyzed using phenetic and multivariate approaches, allowing for the assessment of inter- and intraspecific variation, updated distribution mapping, and preliminary conservation evaluations. Key findings include the recognition of a morphologically coherent subgenus defined by silvery-sericeous indumentum, trifoliolate leaves with reduced lateral leaflets, and distinctive inflorescence and calyx architecture. The revision refines and expands upon Dahlgren's treatment by integrating quantitative analyses, ecological niche data, lecto-typification of historically ambiguous names, and updated distributional records. Several taxonomic adjustments were made, including the elevation of subspecies to species rank (e.g., A. virgata, A. staurantha, A. lagopus), while historically synonymized taxa such as A. elongata var. densa are highlighted as candidates for potential future reinstatement, pending further material and analysis, and the provisional retention of unresolved species pairs (e.g., A. rotunda–A. fragilis). While Dahlgren's core species groups are broadly supported, this study resolves finer infraspecific limits, identifies previously overlooked narrow endemics, and delivers a modern framework for both systematic research and conservation planning in the Cape Floristic Region. In conclusion, this thesis delivers the most comprehensive and integrative study of Aspalathus to date. By combining traditional morphological analysis with cutting-edge phylogenomic tools, it resolves longstanding ambiguities in the genus's classification and provides a robust evolutionary framework for understanding its diversification. The clear separation of Aspalathus into two major clades, now proposed as subgenera, is supported by strong genetic evidence and morphological coherence. This reclassification not only addresses taxonomic confusion but also enhances our ability to interpret evolutionary processes across the group. Importantly, the timing and context of diversification suggest that the Cape Floristic Region's complex environmental mosaic with its fire-adapted ecosystems, heterogeneous soils, and shifting paleoclimates played a central role in shaping the genus's diversity. Rather than being driven solely by aridification, Aspalathus radiated in response to fine-scale ecological opportunities, from edaphic niches to pollination strategies. Therefore, this work contributes not only to the systematics of an ecologically and economically important genus, but also to a broader understanding of how biodiversity emerges and radiates in global hotspots. It provides a model for integrative, genome-informed taxonomy that can be applied to other complex and species-rich plant groups facing similar classification challenges.
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Open Access
Bose condensation in gluon plasma
(2026) Louw, Gary; Peshier, Andre
To explore the possibility of a gluon condensate forming in heavy ion collisions, we study the quantum relativistic Boltzmann equation with glasma-inspired initial conditions. We focus on the standard case of a homogeneous and isotropic gluon plasma. Generalising an existing numerical approach for binary interactions in the scalar 𝜑4-theory to QCD, we develop an efficient framework to estimate equilibration and condensation timescales (to be compared to those for number-changing processes due to inelastic interactions). Our scheme improves on existing test particle simulations and Fokker-Planck approaches based on the small-scattering-angle approximation of the Boltzmann equation. By comparing the latter to our Boltzmann model allows the specification of an auxiliary UV cut-off which hitherto was known only parametrically. Uncertainties are thus reduced to details of QCD screening, which we parametrise with a screening mass and investigate with two different regularisations of the square amplitude. Preliminary results suggest that gluon condensation in heavy ion collisions is less likely than expected from Fokker-Planck approaches, which appear to underestimate equilibration and condensation timescales.