137 research outputs found
Microbial levels on the food preparation areas of a typical district hospital in South Africa
Published ArticleThe role of hospital surfaces (including surfaces in food preparation areas) in the transmission of
hospital-acquired infections (HAI) has been long recognized; however, evidence regarding this critical
information is not well documented. This study was conducted at a typical district hospital in the Free
State Province of South Africa. Using swabs, surface samples were collected from nine kitchen areas,
quantified and identified using the MALDI-TOF MS and API. Fungal counts (1 x 103 to 2.3 x 105 cfu.cm-2)
were higher compared to bacterial counts (1.5 x 103 to 1.1 x 105 cfu.cm-2). A total of 25 bacterial species
and 14 fungal species were identified from hospital kitchen surfaces using the MALDI-TOF MS. Candida
was the most common fungal genus identified represented by 11 species while Bacillus was the most
common bacterial genus isolated represented by 7 species. The presence of species from the genera
Acinetobacter, Enterobacter, Pseudomonas and Candida amongst others on kitchen surfaces could
have serious consequences as they have been implicated in various studies as probable causes of
hospital acquired infections. The study highlights the need to ensure proper cleaning of working
surfaces in the kitchen as well as stringent surveillance and monitoring to ensure the minimal
contamination of food products prepared for patients
South African Mine Effluents: Heavy Metal Pollution and Impact on the Ecosystem
Published ArticleSouth Africa embarks on extensive mining activities, which consequently produce enormous quantities of toxic HMs1 that pollute the surroundings; subjecting the ecosystem to dangers of infections and diseases. Prevalence of HMs in different environmental media and their impact depend on the physical and chemical states of the metal, which tends to persist in their localities because they cannot be biologically or chemically degraded as with organic substances. Mine fugitive dust clouds the environment; in most cases causing irrevocable damage to the biota, with harmful metals usually transferred from water bodies to the food chain via assimilation, bioaccumulation and biomethylation processes
The Occurrence of Bioaerosols in The Food Preparation Areas of HIV/AIDS Hospices in Central South Africa
Characterisation of selected volatile organic compounds in Rwandan indigenous beer ‘Urwagwa’ by dynamic headspace gas chromatography-mass spectrometry
The volatile organic compound profile of alcoholic beverages consists of a wide range of compounds, comprising of acids, alcohols, esters, aldehydes, and other trace level aroma compounds. These compounds play an important role as they provide relative information on the product quality and enhance product acceptability. In this study, two brands of commercially available traditional banana beer samples were collected from a local market in Kigali, Rwanda; and were analyzed for volatile organic compounds. Dynamic headspace, using gas chromatography-mass spectrometry (DHS/GCMS), was used to identify volatile compounds at three different temperatures. Fifty volatile compounds, inclusive of 14 acids, 14 alcohols, and 22 esters were identified and quantified in the two brands of indigenous banana beer samples. Only 12 volatile components (three alcohols, three acids and six esters) were common in all banana beer samples. Among all the identified compounds, ethanol and acetate were the dominant compounds in all beer samples. Ethanol levels were found to be 8.7 and 18.1% (v/v) for brand A and B, respectively using gas chromatography (GC). The two major toxic compounds, methyl alcohol and ethyl carbamate/urethane, were detected in lower concentration levels compared to other identified compounds, thus suggesting negligible risk.Keywords: Indigenous banana beer, volatile compounds, dynamic headspace, gas chromatography-mass spectrometry (GC-MS), ‘Urgwagwa’African Journal of Biotechnology Vol. 12(20), pp. 2990-299
MALDI Biotyper Characterization of Microorganisms Colonizing Heating Ventilation Air-Conditioning Systems at a South African Hospital
Abstract: Airborne microbial contaminants can spread from heating ventilation air conditioning (HVAC) systems resulting in exposure to indoor surfaces and building occupants. Rapid identification of airborne contaminants is a necessity especially in healthcare settings. In the current study, samples were collected from a 5X5 surface area of ventilation grills at a public hospital using swabs. In general bacterial counts were above 12cfu/cm -2 while fungal counts were below 5cfu/cm -2 , ranging from clean (<5) to very contaminated (>10). Microbial contaminants were identified and characterized using the MALDI-TOF MS and Scanning Electron Microscopy. Identified genera included Bacillus, Arthrobacter, Rhodotorula and Penicillium. Microorganisms identified in the current study using the MALDI TOF MS have no reported clinical implications; however, some are potential pathogens due to the presence of immune-compromised patients in these settings. The probable aerosolization of these microorganisms from ventilation systems could result in microorganisms settling on hospital surfaces and possible contamination of medical equipment. The current study also demonstrates the MALDI-TOF MS as a rapid, inexpensive and effective method for microbial characterization of microorganisms isolated from HVAC systems
Genome-wide identification, annotation and characterization of novel thermostable cytochrome P450 monooxygenases from the thermophilic biomass-degrading fungi Thielavia terrestris and Myceliophthora thermophila
Published ArticleCytochrome P450 monooxygenases (P450s)
are ubiquitous heme-thiolate proteins that have potential
biotechnological application. Thermostable-P450s that can
withstand hostile industrial conditions, such as high temperatures,
extremes of pH and organic solvents, are needed
for biotechnological usage. Here, for the first time, we
report a large number of thermostable-P450s from two
thermophilic biomass-degrading fungi, Myceliophthora
thermophila and Thielavia terrestris. Genome-wide P450
analysis revealed the presence of 79 and 70 P450s
(P450ome) in T. terrestris and M. thermophila. Authentic
P450s containing both the P450 signature domains (EXXRand CXG) were classified as follows: T. terrestris (50
families and 56 subfamilies) and M. thermophila (49
families and 53 subfamilies). Bioinformatics analysis of
P450omes suggested the presence of a large number of
thermostable-P450s. Based on aliphatic index cut-off
([90), 14 and 11 P450s were determined to be thermostable
in T. terrestris and M. thermophila. Among the
thermostable P450s, six P450s from T. terrestris and three
from M. thermophila had a melting temperature (Tm) of
[65 C, suggesting their hyperthermal tolerance. Analysis
of the instability index of two ascomycete P450omes
revealed the presence of 12 and 19 in vitro stable P450s in
T. terrestris and M. thermophila. Overall, six P450s from
T. terrestris and four from M. thermophila showed both
thermal tolerance and in vitro stability. Thermophilic
ascomycetes P450s are of potential interest from a structural,
mechanistic and biotechnological point of view, as
five P450s showed higher thermal tolerance and five
showed higher in vitro stability compared to the wellcharacterized
thermostable-P450s CYP175A1 (bacteria)
and CYP119 (archaea)
Functional Evolution of Free Quantum Fields
We consider the problem of evolving a quantum field between any two (in
general, curved) Cauchy surfaces. Classically, this dynamical evolution is
represented by a canonical transformation on the phase space for the field
theory. We show that this canonical transformation cannot, in general, be
unitarily implemented on the Fock space for free quantum fields on flat
spacetimes of dimension greater than 2. We do this by considering time
evolution of a free Klein-Gordon field on a flat spacetime (with toroidal
Cauchy surfaces) starting from a flat initial surface and ending on a generic
final surface. The associated Bogolubov transformation is computed; it does not
correspond to a unitary transformation on the Fock space. This means that
functional evolution of the quantum state as originally envisioned by Tomonaga,
Schwinger, and Dirac is not a viable concept. Nevertheless, we demonstrate that
functional evolution of the quantum state can be satisfactorily described using
the formalism of algebraic quantum field theory. We discuss possible
implications of our results for canonical quantum gravity.Comment: 21 pages, RevTeX, minor improvements in exposition, to appear in
Classical and Quantum Gravit
Defining the microbial transcriptional response to colitis through integrated host and microbiome profiling
The gut microbiome is significantly altered in inflammatory bowel diseases, but the basis of these changes is not well understood. We have combined metagenomic and metatranscriptomic profiling of the gut microbiome to assess modifications to both bacterial community structure and transcriptional activity in a mouse model of colitis. By using transcriptomic analysis of colonic tissue and luminal RNA derived from the host, we have also characterised how host transcription relates to the microbial transcriptional response in inflammation. In colitis, increased abundance and transcription of diverse microbial gene families involved in responses to nutrient deprivation, antimicrobial peptide production and oxidative stress support an adaptation of multiple commensal genera to withstand a diverse set of environmental stressors in the inflammatory environment. These data are supported by a transcriptional signature of activated macrophages and granulocytes in the gut lumen during colitis, a signature that includes the transcription of the key antimicrobial genes S100a8 and S100a9 (calprotectin). Genes involved in microbial resistance to oxidative stress, including Dps/ferritin, Fe-dependent peroxidase and glutathione S-transferase were identified as changing to a greater extent at the level of transcription than would be predicted by DNA abundance changes, implicating a role for increased oxygen tension and/or host-derived reactive oxygen species in driving transcriptional changes in commensal microbes
Evaluating the Influences of Natural Resources and Ageing People on CO2 Emissions in G-11 Nations: Application of CS-ARDL Approach
Globalization as well as the ratio of ageing people in the group of 11 (G-11) countries has seen a rapid increase in recent years. Therefore, this study aims to provide effective policy recommendations for sustainable development goals 13, 8, and 7, for the G-11 countries. This work estimates the impact of natural resources and the ageing population on the emission of carbon dioxide (CO2) in G-11 countries using panel data from 1990–2020. For empirical results, second-generation methods were applied. The Westerlund co-integration test that assesses co-integration confirms the firm association among the parameters, and the values of coefficient of the cross-sectional autoregressive distributed lag (CS-ARDL) approach show that a 1% increase in the ageing population will lower the emissions of CO2 by 13.41% among G-11 countries. Moreover, the findings show that there exists an environmental Kuznets curve (EKC) among natural resources, globalization, economic growth, ageing people, and the emission of CO2. Based on the findings, this work presents some important policy implications for achieving sustainable growth in the G-11 countries. These countries need to lower the amount of energy obtained from fossil fuels to improve air quality. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Quantizing the damped harmonic oscillator
We consider the Fermi quantization of the classical damped harmonic
oscillator (dho). In past work on the subject, authors double the phase space
of the dho in order to close the system at each moment in time. For an
infinite-dimensional phase space, this method requires one to construct a
representation of the CAR algebra for each time. We show that unitary dilation
of the contraction semigroup governing the dynamics of the system is a logical
extension of the doubling procedure, and it allows one to avoid the
mathematical difficulties encountered with the previous method.Comment: 4 pages, no figure
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