Browsing by Author "Dhlamini, Z."

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    Cloning Cellulase Genes from Victoria Falls Rainforest Decaying Logs Metagenome
    (Sciendo, 2024) Nyathi, M,; Dhlamini, Z.; Ncube, T.
    The Victoria Falls rainforest is a protected site whose forest floors harbor a host of cellulolytic microorganisms involved in biomass degradation. This study collected decaying logs and soil from the rainforest for bioprospecting cellulases from their metagenomes. Metagenomic DNA was isolated from the compound sample. Degenerate cellulase primers were used to amplify cellulase genes in the metagenome. The resulting amplicons cloned into Z-competent Escherichia coli DH5α were analyzed by functional screening for the production of cellulase extracellularly. Functional screening of the clones resulted in one clone (Clone-i) testing positivefor extracellular cellulase production. Submerged fermentation of Clone-i was carried out for cellulase production. The cellulases were characterized to determine their activity’s optimum pH and temperature. The diversity of the cellulases produced by Clone-i was determined. Clone-i’s optimum enzyme activity was observed after 72 hours of incubation at 50°C and pH 5. Clone-i produced 80% more exoglucanases as compared to endoglucanases. The cel- lulolytic Clone-i’ isolate shows Victoria Falls rainforest’s potential as an enzyme bioprospecting site, reflecting that metagenomics is a valuable tool in microbial ecology.
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    Molecular Characterization of Aflatoxigenic Aspergillus species in dried Traditional foods in Zimbabwe
    (Society of Education, 2014-01-10) Dangwa, N.; Mwenje, E.; Dhlamini, Z.; Siwela, A.H
    The presence of aflatoxin producing Aspergillusspp in sixty samples of six selected traditional foods sold on the Bulawayo open market in Zimbabwe was investigated. Ten samples of each of the following commodities were bought from the market; dried groundnuts, dried cowpeas, dried maize, dried cowpea leaves, dried mopane worms and dried Cleome gynandra leaves and analysed for the presence of aflatoxigenic aspergillus. Moisture content of the samples was determined and another portion of the samples was plated on petri dishes containing Sabouraud Dextrose Agar (SDA) and incubated at 28 C. A total of 35 isolates was obtained and these were characterised according to their morphology as well as the type of aflatoxins they produced as determined by thin layer chromatography. Four distinct morphological groups were found and they were classified as Aspergillu sparasiticus (57%); Aspergillusniger (17%); Aspergillus tamarii (17%) and Aspergillusflavus (8%). These results were validated by using DNA primers of the structural genes, aflD (nor-1), aflM (ver-1) and aflP (omt-1) and the regulatory gene aflR to discriminate between aflatoxigenic and nonaflatoxigenic strains after amplifying DNA of the fungal strains. None of the isolates produced all the four genes involved in the aflatoxin biosynthetic pathway although they had shown positive results on the biochemical tests. Out of the 35 isolates obtained, 18 of them were aflatoxigenic and these isolates were from mopane worms (9), cowpeas (4), groundnuts (3) and Cleome gynandra (1). This investigation showed that dried traditional foods in Zimbabwe were contaminated by the aflatoxigenic fungus, Aspergillus, probably due to improper drying of the commodities, coupled by prevailing environmental conditions from packaging to the selling points.
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    SARS-CoV-2 Serological testing in frontline health workers in Zimbabwe
    (PLoS Neglected Tropical Diseases, 2021-03-31) Rusakaniko, S.; Sibanda, E.N.; Mduluza, T.; Tagwireyi, P.; Dhlamini, Z.; Ndhlovu, C.E.; Chandiwana, P.; Chiwambutsa, S.; Lim, R.M.; Scott, F.; Sibanda, L. M.
    Background In order to protect health workers from SARS-CoV-2, there is need to characterise the different types of patient facing health workers. Our first aim was to determine both the infection status and seroprevalence of SARS-CoV-2 in health workers. Our second aim was to evaluate the occupational and demographic predictors of seropositivity to inform the country’s infection prevention and control (IPC) strategy. Methods and principal findings We invited 713 staff members at 24 out of 35 health facilities in the City of Bulawayo in Zimbabwe. Compliance to testing was defined as the willingness to uptake COVID-19 testing by answering a questionnaire and providing samples for both antibody testing and PCR testing. SARS-COV-2 antibodies were detected using a rapid diagnostic test kit and SAR-COV-2 infection was determined by real-time (RT)-PCR. Of the 713 participants, 635(89%) consented to answering the questionnaire and providing blood sample for antibody testing while 560 (78.5%) agreed to provide nasopharyngeal swabs for the PCR SARS-CoV-2 testing. Of the 635 people (aged 18–73) providing a blood sample 39.1% reported a history of past COVID-19 symptoms while 14.2% reported having current symptoms of COVID-19. The most-prevalent co-morbidity among this group was hypertension (22.0%) followed by asthma (7.0%) and diabetes (6.0%). The SARS-CoV-2 sero-prevalence was 8.9%. Of the 560 participants tested for SARS-CoV-2 infection, 2 participants (0.36%) were positive for SAR-CoV-2 infection by PCR testing. None of the SARS-CoV-2 antibody positive people were positive for SAR-CoV-2 infection by PCR testing. Conclusion and interpretation In addition to clinical staff, several patient-facing health workers were characterised within Zimbabwe’s health system and the seroprevalence data indicated that previous exposure to SAR-CoV-2 had occurred across the full spectrum of patient-facing staff with nurses and nurse aides having the highest seroprevalence. Our results highlight the need for including the various health workers in IPC strategies in health centres to ensure effective biosecurity and biosafety.