ResearchSpace
ResearchSpace is the institutional repository of the University of KwaZulu-Natal, unlocking knowledge, empowering impact, and preserving UKZN's research legacy.
Recent Submissions
Characterization of antimicrobial properties of pleurotus ostreatus-derived phenolic compounds: Implications for drug development against antibiotic-resistant neisseria gonorrhoeal isolates.
(2024) Yakobi, Sinethemba Hopewell.; Pooe, Ofentse Jacob.
The global spread of antimicrobial resistance in Neisseria gonorrhoeae presents a major challenge to treating gonorrhoeal infections, necessitating immediate intervention strategies. This study investigates the prevalence and mechanisms of antibiotic resistance in N. gonorrhoeae isolates from KwaZulu Natal, South Africa, where antimicrobial resistance monitoring is limited. Utilizing molecular and culture methods, significant resistance levels were detected: 48% of isolates were fully resistant to ciprofloxacin, 14% to both penicillin and tetracycline, and one isolate showed resistance to azithromycin, while ceftriaxone remained universally effective. The extracts exhibited varying antimicrobial activities against E. coli and S. aureus, with a mean extract concentration of 1x10-5 mg/mL. In contrast, N. gonorrhoeae isolates showed a mean MIC concentration of 1x10-3 mg/mL, indicating a higher resistance to the target extracts compared to E. coli and S. aureus. The high resistance to penicillin, with MICs exceeding 32 μg/mL, is attributed to the presence of penicillinase-producing plasmids and mutations in penicillin-binding proteins (PBPs), particularly in the penA gene.
Logistic regression indicated a strong correlation between bacterial growth rates and tetracycline concentrations, emphasizing the complexity of resistance dynamics. The study also explored flavonoid compounds as alternative therapies, with quercetin showing notable antibacterial properties. Molecular docking and dynamics simulations were employed to examine quercetin's interaction with critical bacterial proteins, penicillin-binding protein 2 (PBP2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), essential for cell wall synthesis and metabolism. Quercetin demonstrated strong binding affinity to the active sites of these proteins, potentially inhibiting their function. Molecular dynamics (MD) simulations provided insights into the long-term stability and dynamic behaviour of the quercetin-protein complexes, showing consistent and secure binding within the active sites of PBP2 and GAPDH. Analysis of rootmean- square deviation (RMSD) and root-mean-square fluctuation (RMSF) confirmed the stability of these protein structures during simulation. Binding-free energy calculations using the molecular mechanics method confirmed quercetin's strong inhibitory potential against both PBP2 and GAPDH. Structural insights from Procheck and other computational tools identified crucial residues in the binding pockets, providing valuable information for developing more effective quercetin derivatives or other flavonoid-based therapeutics. This comprehensive study underscores quercetin as a promising alternative treatment for drugresistant N. gonorrhoeae and emphasizes the need for continued exploration of flavonoid compounds in combating antimicrobial resistance. The findings advocate for a global collaborative effort to combat antimicrobial resistance in N. gonorrhoeae, involving robust surveillance systems, advanced molecular techniques, and novel antimicrobial agents to curb the spread of resistant strains,ensure effective treatment, and safeguard public health.
Fourteen years of retinopathy of prematurity in KwaZulu-Natal, South Africa.
(2024) John, Jerusha Shanthi.; Du Bruyn, Magritha.; Kruse, Carl-Heinz.
This thesis addresses a critical need in neonatal healthcare: preventing blindness and severe vision impairment caused by retinopathy of prematurity (ROP) among preterm infants in KwaZulu-Natal, South Africa. With advances in neonatal care enabling the survival of smaller, more vulnerable infants, ROP has become a pressing public health issue. This project aimed to evaluate the impact of the South African ROP screening guidelines introduced nearly a decade ago and to assess the current state of ROP detection and screening in KwaZulu-Natal. By analysing referral patterns, patient demographics, and screening outcomes, the study aimed to understand the effects of the guidelines and identify areas where care could be further improved. To achieve these objectives, the study followed an approach that involved analysing clinical data on ROP referrals from neonatal intensive care units (NICUs) across eastern KwaZulu-Natal. This included examining ROP referral rates, patient demographics, screening compliance, and treatment numbers to capture trends before and after implementing the guidelines, the identification of trends and areas requiring intervention. The project’s outputs include an evaluation of the effectiveness of the ROP screening guidelines, revealing notable reductions in treatable ROP cases and improvements in neonatal eye health overall. However, it also uncovered persistent challenges, such as inconsistent referral practices across facilities, large variability in guideline adherence, and a concerning rate of missed follow-up appointments. These insights have implications for healthcare policy and practice, suggesting that while the guidelines are largely beneficial, targeted efforts are needed to address gaps in referral practices and patient follow-up. The impact of this project is important for both clinical practice and public health policy. The project advocates for focused education and monitoring efforts, especially in facilities with high inappropriate referral rates, to enhance ROP screening efficacy. In doing so, the study supports ongoing improvements to neonatal care, aiming to safeguard vision health among the most vulnerable infant populations in South Africa and beyond.
Mucuna pruriens L. (DC) and Arachis hypogaea (L.) enhance soil biological and chemical properties of nutrient-deficient small-scale sugarcane soils.
(2025) Khwela, Sikhanyiso Bright.; Magadlela, Anathi.; Ramdhani, Syd.
Most of the rural population in South Africa rely on agriculture for food security and livelihood. In KwaZulu-Natal, sugarcane production plays a significant role in the livelihoods of smallscale farmers in rural areas. However, there has been a decline in sugarcane productivity and yield due to soil-health-related problems caused by long-term monoculture and excessive chemical fertilizer use. Legume cover cropping is an attractive and sustainable alternative to reduce overreliance on synthetic nitrogen (N) fertilizers since legumes increase soil N levels through symbiotic N fixation. Mucuna pruriens L. (DC) and Arachis hypogaea L. have been reported to fix approximately 34-242 kg N ha-1 and 150-200 kg N ha-1, respectively.
Furthermore, these legume species have been reported to provide ecosystem services such as nutrient cycling, weed suppression, soil erosion control, increased organic matter, and microbial diversity. Therefore, this study investigated the effects of cultivating M. pruriens and A. hypogaea on the soil chemical characteristics, bacterial community composition, and enzyme activities of five different acidic and nutrient-deficient sugarcane plantation soils in KwaZulu-Natal, South Africa. Additionally, the study evaluated the N-source preference, biomass accumulation, and plant nutrition of M. pruriens and A. hypogaea growing in these acidic and nutrient-deficient sugarcane soils. Post-harvesting, the soil pH increased across all study sites for both legume species. Both M. pruriens and A. hypogaea sanctioned for Ncycling, N-fixing, and P solubilizing bacteria with the dominant strains belonging to the Burkholderia and Pseudomonas genera. The increase in P solubilizing bacteria, alkaline and acid phosphatase activity assisted with the demands of biological N fixation, allowing M. pruriens and A. hypogaea to fix 26-58% and 40-70% of N from the atmosphere, respectively.
Overall, the findings of this study showed that M. pruriens and A. hypogaea contribute to soil health improvement by reducing soil acidity and increasing the diversity of nutrient-cycling bacteria and their associated enzyme activities in small-scale sugarcane soils.
The effects of thermal stress on the physiology of two high-latitude corals from the environmentally variable intertidal and moderate subtidal habitats.
(2025) Boodraj, Prishani Devi.; Glasson, David.; Vosloo, Dalene.
Corals are of great ecological and economic importance; however, they are increasingly threatened by mass bleaching events caused by ocean warming, which has become more frequent and is predicted to increase in frequency and severity in the coming years. The degree of coral bleaching, recoverability, and mortality is highly variable and considered to be affected by the coral’s physiological and antioxidant capacity and the thermal regimes they experience. These mechanisms are still poorly understood and need to be investigated in different coral species from varying environmental regimes when exposed to prolonged thermal stress and during recovery to better inform conservation measures. Coral communities found on the subtropical East Coast of South Africa can be defined as ‘extreme’ due to the sub-optimum environmental conditions experienced especially in intertidal habitats and ‘marginal’ since, ecologically, they are not true accretive reefs. Climate change has not caused severe bleaching in corals of this region, but the physiological mechanisms that influence their thermal resilience/susceptibility are yet to be investigated. Therefore, this thesis examined the thermal resilience/susceptibility of Anomastraea irregularis (massive morphology) and Pocillopora verrucosa (branching morphology) from the intertidal and subtidal zones of the understudied rocky shores of Treasure Beach, east coast KwaZulu-Natal province, South Africa using both laboratory and field studies. The intertidal pools in this region are highly dynamic, with large summer daytime fluctuations of more than 10°C at spring tide while the subtidal zone is notably more environmentally stable. These corals were maintained in closed recirculating aquaria and exposed to two constant thermal stress conditions (control: 26°C, thermal stress treatments: 28°C and 30°C) for three months and then were maintained at control conditions for two months to monitor recovery. Respiration, photosynthetic, and growth rates were measured monthly. The Symbiodiniaceae density, chlorophyll-a concentration, chlorophyll-a concentration per symbiont cell, lipid concentration, protein concentration, antioxidant enzyme activity (superoxide dismutase, catalase, glutathione peroxidase, glutathione s-transferase), and caspase 3 activity were analysed at the start and end of the thermal stress as well as at the end of the recovery period. The thermal stress treatments induced bleaching (significant decrease in Symbiodiniaceae density and chlorophyll-a concentrations) in both species from both habitats with associated significant decrease in photosynthetic and growth rates. Increased oxidative stress was also evident with the increased superoxide dismutase, catalase, glutathione peroxidase, and caspase 3 activity in fragments in both thermal stress treatments at the start and end of thermal stress and at the end of recovery.
There were inherent physiological differences between the species and habitat that were maintained throughout the experiment, highlighting that variable thermal regimes and coral species can influence coral resilience to thermal stress. The intertidal corals were more resilient (less bleaching and fewer deaths) than their subtidal conspecifics, and A. irregularis appeared more resilient than P. verrucosa in both thermal stress treatments. The intertidal corals could lower their respiration rates to that of the control rates by the end of thermal stress and maintained higher Symbiodiniaceae densities, chlorophyll-a, and lipid concentrations than their= subtidal conspecifics throughout the study. Resilience of A. irregularis may be a result of its thicker tissue, which allowed higher Symbiodiniaceae density and lipid concentrations and lower P:R ratios demonstrative of a more heterotrophic nature. Overall, higher protein concentrations and lower antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) were evident in intertidal fragments than subtidal fragments and A. irregularis than P. verrucosa when thermally stressed. The higher protein concentrations may have facilitated the corals’ physiological processes that made them more resilient to prolonged thermal stress. Therefore, these corals may have had lower antioxidant activities because of less oxidative stress. The results indicated much higher antioxidant activity in susceptible corals, suggesting that oxidative stress may be responsible for higher bleaching and mortalities. The photosynthetic and growth rates, Symbiodiniaceae density, chlorophyll-a concentration, and lipid concentration of both species from both habitats did not fully recover two months after thermal stress. Similarly, the antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase), and caspase 3 activities of both species from both habitats did not decrease to control levels at the end of recovery, indicating that a longer period would be required for full recovery of the biochemical and physiological pathways of these corals. This has implications for coral reef recovery trajectories in situ since less time between mass bleaching events is predicted in the near future.
Field studies are important for validating the physiological responses found during laboratory studies since the static nature of laboratory experiments cannot account for the dynamic environmental conditions corals encounter in situ. A pilot study was conducted to determine if the ‘flexi-chamber’ and photogrammetry could be used to track respiration, photosynthesis, and growth of A. irregularis and P. verrucosa fragments (3 cm > 4 cm) in the intertidal and subtidal habitats in Park Rynie, east coast KwaZulu-Natal province, South Africa. This study found that the two methods could be optimised to effectively measure the physiological processes of coral fragments in both habitats at relatively low cost and low complexity.
To understand the physiological responses of these species when exposed to thermal stress in their natural habitats an in-situ experiment at Treasure Beach was conducted during the warmer austral spring and summer months where fragments of both species were reciprocally transplanted between the two habitats. Controls were established by placing fragments in their original habitats. Respiration, photosynthesis, growth rates, and coral health scores were measured monthly for six months. The physiological rates were measured using the optimised methods that were obtained during the pilot study. The Symbiodiniaceae density, chlorophyll-a concentration, chlorophyll-a concentration per symbiont cell, and lipid concentration were also
analysed at the start and end of the study. Similar to the laboratory results, differential physiological responses between species and habitat were evident in response to the reciprocal transplantation. Intertidal A. irregularis and P. verrucosa transplanted into the subtidal habitat showed potential acclimation to the subtidal habitat. These fragments were able to adjust their P:R ratios and maintain higher Symbiodiniaceae cell density, Symbiodiniaceae chlorophyll-a concentration, and Symbiodiniaceae chlorophyll-a concentration per cell, and lipid content thereby experiencing less bleaching and mortalities. Anomastraea irregularis appeared more physiologically plastic (altering respiration rates and maintaining higher Symbiodiniaceae cell density and lipid concentration) and therefore more tolerant (less bleaching and mortalities) than P. verrucosa to the changes in environmental conditions.
The laboratory and field results add to the limited knowledge of how high-latitude corals of different species and from habitats of differing environmental regimes react physiologically to long-term thermal stress. The results are promising since these resilient corals may be used in
future conservation initiatives. The results of this thesis show the ability of some coral species to acclimatise and/or adapt to different environmental conditions, however, the potential for these corals to acclimatise/adapt to global climate change related stressors still warrants further
investigation especially since several other stressors are also impacting reef systems.
Physiological and genotypic analyses of the African leafy vegetable, Amaranthus dubius, in response to environmental stresses and cryopreservation.
(2025) Haripershad, Ashiq.; Shaik, Shakira.
Africa’s population is predicted to double by 2050. However, the current population’s dietary demand exceeds the agricultural output capacity of arable land and irrigable water. This issue is further exacerbated by the climate crisis, causing unpredictable rainfall and weather patterns and influencing
soil quality and water supply. Identifying under-utilised crops that are resistant to water-deficit, soil salinity, and high temperatures can therefore mitigate some of these challenges to secure a sustainable food supply. Furthermore, long-term preservation of identified resilient genotypes is
necessary to safeguard germplasm for future research and use. It is, therefore, also necessary to investigate post-storage plant growth and development to determine viability retention and true-totype genetic fidelity.
Amaranthus dubius, an under-utilised African leafy vegetable, thrives in southern Africa and is a nutritious food source containing many essential vitamins, minerals, and nutrients. This annual shrub can also tolerate environmental stresses and remains resilient on marginal lands. However,
phenotypic variations observed in wild-type populations, including altered growth rates and biomass partitioning, result in reduced nutrient concentrations and yield, unpredictable quality, and overall agricultural inefficiency, hindering propagation and cultivation. Furthermore, the underlying genetic regulation of these stress responses has not been investigated, representing a missing step towards improving crop resilience, resource-use efficiency, and developing propagation strategies. This study aimed to elucidate the growth, physiological and genetic responses of A. dubius to waterdeficit, soil salinity, high-temperature, and preservation stresses, thereby identifying superior, resilient genotypes. Phenotypic responses were quantified by individually exposing A. dubius seedlings to each stress and measuring various growth and physiological parameters. Genetic expression was measured by quantifying mRNA transcripts of stress-responsive genes. This data was used to identify and clonally propagate superior genotypes, through cuttings and in vitro propagation, to conserve desired traits and increase scalability for greater agricultural capacity.
Multiple stress-tolerant specimens of A. dubius were identified by measuring biomass, shoot height, leaf area, water pressure potential, electrical conductivity, and contents of total chlorophyll, proline, and protein. Proteins were characterised in water-deficit and heat stress tolerant genotypes. The
expression of putative Na+/H+ antiporter transcripts was quantified using degenerately-primed realtime qPCR, revealing a mechanism of ionic stress tolerance whereby toxic solutes were increasingly compartmentalised in roots rather than foliar tissues under salinity stress. Quantification of waterdeficit, high-temperature and cryopreservation-responsive transcripts requires further optimisation. Nevertheless, this research produced water-deficit, salinity, high-temperature and preservationtolerant clonal genotypes of A. dubius, aiding the struggle for food security in southern Africa. This
work culminated in the expansion of indigenous knowledge and facilitates future studies regarding gene identification, sequencing, and the possible development of transgenic crops to withstand achanging climate.