http://hdl.handle.net/11189/490 2026-09-01T14:49:37Z http://hdl.handle.net/11189/10770 Title: ualitative and quantitative evaluation of bacterial polyhydroxyalkanoates: a critical review of existing methodologies Authors: Ranjan, Amrita; Mthethwa, Thandekile; Welz, Pamela Abstract: Polyhydroxyalkanoates (PHAs) are non-toxic aliphatic polyester biopolymers that are gaining traction as bio-based and biodegradable materials. To support the growing body of research on this subject, scientists and other stakeholders require insight into the synthesis, structure and quantity of PHA produced by bacterial isolates. To address the challenges that researchers face when seeking to evaluate bacterial PHA production, this manuscript presents a cohesive collection and critical evaluation of the methods described in literature, highlighting the applications, advantages, and disadvantages of each. Environmental samples are typically screened for PHA production based on uptake of lipophilic dyes. Thereafter, quantification of polyhydroxybutyrate and/or polyhydroxyvalerate monomers is typically performed using gas chromatography or high-performance liquid chromatography. These methods are robust with good specificity, but their application range is limited by non-availability of commercial standards. Methods based on lipophilic fluorescent dye emissions measured by spectrofluorometry or flow cytometry present simple, cost effective and efficient alternatives, but there are issues related to lack of specificity. For identification and quantification of monomers other than polyhydroxybutyrate and/or polyhydroxyvalerate, and to elucidate monomeric spatial arrangements within the polymer structure requires more sophisticated equipment and skilled analyses including gas chromatography-mass spectrometry, high performance liquid chromatography-mass spectrometry, and finally nuclear magnetic resonance. These methods are presented and discussed, along with other ancillary methods including Raman spectroscopy and Fourier-transform infrared spectroscopy, and methods based on molecular biology principles. 2025-01-01T00:00:00Z http://hdl.handle.net/11189/10748 Title: Screening and targeted sequencing of stool for microbiologic confirmation and drug resistance determination in paucibacillary tuberculosis Authors: Ness, Tara; Ziyane, Mangaliso; Maphalala, Nontobeko; Seeger, Abigail; Vasiliu, Anca; Khumalo, Wethusonke; Thunzini, Mdigo; Dlamini, Sindisiwe; Maphalala, Gugu; Gascua Adu-Gyamfi, clement; Lange, Christoph; Inman, Bryce; Dreyer, Viola; Utpatel, Christian; Niemann, Tanja; DiNardo, Andrew; Kay, Alexander; Niemann, Stefan Abstract: In 2023, an estimated 10.8 million people developed tuberculosis, and 1.25 million people died from this disease, including 161,000 deaths in people with HIV (PWH) in whom tuberculosis remains the leading cause of death. Detecting Mycobacterium tuberculosis drug resistance remains a challenge among patients with paucibacillary tuberculosis; since there is such low bacterial load in their sputum it’s unable to be detected via microscopy, there is also not enough bacteria for other sputum-based tests which could provide resistance testing. At an outpatient clinic in Eswatini from 2020-2023, stool and sputum samples were provided by a subset of children, adolescents, and adults prospectively enrolled in a tuberculosis diagnostic study. In addition to standard diagnostic testing available in country (direct sputum Xpert, stool Xpert, and phenotypic drug susceptibility testing of sputum culture), stool samples underwent extraction and sequencing using targeted next generation sequencing (tNGS), using both the Oxford Nanopore Technologies (ONT) TB Custom Kit (on an ONT MinION Mk1b) and the Deeplex Myc-TB kit (on an Illumina iSeq 100). From 250 participants with pulmonary tuberculosis diagnosed in Eswatini during our study period, 85 (34%) were smear negative on sputum microscopy. Of these, 21/85 (24.7%) participants had adequate M. tuberculosis DNA shed in their stool for attempting tNGS. Targeted sequencing on stool detected M. tuberculosis DNA in 14–19% (n = 12/85–16/85) and provided a full report of mutations associated with drug resistance in 12–14% (n = 10/85–12/85) of patients with paucibacillary (smear-negative) tuberculosis, expanding drug resistance detection beyond other methods. Targeted sequencing of stool, even when applied to patients with paucibacillary disease, can provide case confirmation and expanded drug resistance information. 2025-01-01T00:00:00Z http://hdl.handle.net/11189/10747 Title: Phytofabrication of silver nanoparticles using Ehretia rigida leaf aqueous extract, their characterization, antioxidant and antimicrobial activities Authors: Oselusi, Samson O.; Sibuyi, Nicole Remaliah Samantha; Meyer, Mervin; Meyer, Samantha; MADIEHE, ABRAM Abstract: The green synthesis of nanoparticles (NPs) offers a sustainable, rapid, and cost-effective alternative to traditional chemical and physical methods, with diverse applications across various fields. This study reports the synthesis of silver nanoparticles (AgNPs) using Ehretia rigida (Er) leaf aqueous extract and evaluates their biological activities. The formation of the NPs was confirmed by the change in colour from clear to dark brown. The synthesis parameters, such as pH, temperature, Er extract and silver nitrate (AgNO3) concentrations, reaction ratio, and incubation time, were optimized for high yields, controlled size, and stability of the NPs. The optimized Er-AgNPs were characterized using ultraviolet–visible (UV–vis) spectroscopy, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, and high-resolution transmission electron microscopy (HR–TEM). The Er-AgNPs sample presented a characteristic absorbance peak at 408 nm, a hydrodynamic size of 74.02 ± 0.19 nm, a polydispersity index (PDI) of 0.39 ± 0.05, and a zeta potential of −25.4 ± 6.26 mV. FTIR analysis revealed the nature of the biomolecules responsible for the reduction and stabilization of the NPs. HR–TEM revealed that the Er-AgNPs were spherical, with core sizes ranging from 6 to 18 nm. The Er leaf aqueous extract and Er-AgNPs possessed antioxidant activities, with the Er leaf extract having higher activity than Er-AgNPs. The Er leaf extract did not exhibit any antimicrobial activity, whereas the Er-AgNPs demonstrated broad-spectrum antimicrobial activities against all the tested pathogens. This study provides a sustainable, easy and cost-effective method to produce AgNPs for biomedical applications. 2025-01-01T00:00:00Z http://hdl.handle.net/11189/10740 Title: Are polymorphisms within the fructosamine-3-kinase gene associated with the discordance between HbA1c and other measures of glycemia? Authors: Motshwari, Dipuo Dephney; George, Cindy; Ngwa, Ndonwi Elvis; Zemlin, Annalise E.; Kengne, Andre. P.; Davison, Glenda Mary; Erasmus, Rajiv; Matsha, Tandi Abstract: Glycated hemoglobin has shown disagreements with other glycemic indices; termed the glycation gap. The glycation gap can be influenced by nonglycemic factors, such as protein deglycation, through the fructosamine-3-kinase (FN3K) enzyme. This cross-sectional study aimed to examine whether single nucleotide polymorphisms (SNPs) in the FN3K gene can explain the glycation gap. Among the 826 participants, 79.8% were female, 22.3% presented with diabetes, and the median age was 53 years. The results suggest that genetic polymorphisms in the FN3K gene may influence the glycation gap in individuals with diabetes. With the SNP rs1056534 analysis, the CC genotype was associated with a negative glycation gap (all P < 0.02), whereas the GG genotype was associated with a positive glycation gap (all P < 0.03) in the adjusted models. Similarly, with the SNP rs2256339, the TT genotype was associated with a negative glycation gap (P < 0.08), whereas the TA genotype was associated with a positive glycation gap (all P < 0.05) in the adjusted models. The studied genotypes are associated with protein glycation, contributing to differences in measures of glycemic control. Future studies are needed to explore the clinical implications of these findings. 2025-01-01T00:00:00Z