Research Publications (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213

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Chitinase from Thermomyces lanuginosus SSBP and its biotechnological applications
(Springerlink, 2015) Khan, Faez Iqbal; Bisetty, Krishna; Singh, Suren; Permaul, Kugen; Hassan, Md. Imtaiyaz
Chitinases are ubiquitous class of extracellu-lar enzymes, which have gained attention in the past few years due to their wide biotechnological applications. The effectiveness of conventional insecticides is increasingly compromised by the occurrence of resistance; thus, chi-tinase offers a potential alternative to the use of chemical fungicides. The thermostable enzymes from thermophilic microorganisms have numerous industrial, medical, envi-ronmental and biotechnological applications due to their high stability for temperature and pH. Thermomyces lanug-inosus produced a large number of chitinases, of which chi-tinase I and II are successfully cloned and purified recently. Molecular dynamic simulations revealed that the stability of these enzymes are maintained even at higher tempera-ture. In this review article we have focused on chitinases from different sources, mainly fungal chitinase of T. lanug-inosus and its industrial application.
Development of an energy-dense biscuit suitable for primary school learners for the South African National School Nutrition Programme
(African Journal of Food, Agriculture, Nutrition and Development, 2021) Hassanally, Saffia; Naicker, Ashika; Singh, Evonne
South Africa has a well established National School Nutrition Programme (NSNP). Despite rescheduling the mealtime to two hours after the start of the school day to accommodate learners who come to school on an empty stomach, a gap still exists as many children start their learning day with low energy and concentration levels. A cost-effective, energy-dense snack served at the start of the school day can be a solution to sustain learners until the main meal is served. Cross-sectional surveys were used to determine the snack preferences of children and the product development process was used to develop a suitable snack. An energy-dense peanut butter biscuit was developed based on those surveys as well as a scoping review of previous snack studies. The energy-dense developed product provided 1388kJ (61.0%) of energy from fat, 688kJ (30.2%) of energy from carbohydrates and 201kJ (8.8%) of energy from protein per 100g. The biscuit conformed to microbial testing standards. Shelf-life analysis projected a shelf-life of five weeks fresh and five months in food grade packaging. Sensory results showed that there was no significant difference in sensory scores across gender (p=0.691) and age (p=0.706). More of the learners (n=56, 69.1%) found the biscuit to be ‘Super good’ than the other ratings (p<.0005). When compared with similar biscuit products currently on the market, it was found that the developed biscuit was the most reasonably priced. The developed biscuit has the potential to serve as a solution to hidden hunger for children that come to school on an empty stomach. This versatile snack solution has potential for continuity of use even during periods of national crisis as with COVID-19, when learners’ nutritional needs may be most vulnerable.
Digitalization in developing maritime business environments towards ensuring sustainability
(MDPI, 2020-11-06) Kapidani, Nexhat; Bauk, Sanja; Davidson, Innocent E.
The paper focuses on assessing the level of digitalization in several developing maritime business environments in Albania, Bosnia and Herzegovina, Montenegro, and Serbia. The assessment has been done in reference to Holtham’s and Courtney’s Intelligent Information and Communication Technologies (ICT) Exploiter Model. The dimensions as maritime business system effectiveness, roles, and skills of information technology personnel, ladders of knowledge, ICT strategy, organizational culture, and manager’s mindset are analyzed. In addition, benchmarking with findings from developed maritime business environments in Croatia, Greece, Italy, and Slovenia, which belong to the European Union (EU), by using the same model, has been conducted. This is done with the aim to outline directions for improving the quality and speed of digitalization in non-EU countries, which have been functioning for decades in transitional conditions. The maritime ecosystem naturally has a tendency to be unique and to function smoothly as such. Alleviating the differences in the level and effectiveness of digitalization in developed and developing European countries is a path towards achieving this goal. By sharing their own expertise in the rational and intelligent use of ICT, developed EU countries can support developing non-EU countries towards ensuring sustainability in the entire European and worldwide maritime business ecosystem.
Effect of internal woven roller shade and glazing on the energy and daylighting performances of an ofﬁce building in the cold climate of Shillong
(Elsevier, 2015) Singh, Ramkishore; Lazarus, Ian Joseph; Kishore, V.V.N.
The energy and visual performances of the façades are deﬁned by many parameters including façade size, properties of glazings and shadings, and their arrangements as well as control strategies. In this study, a number of combinations of internal woven roller shades and four double glazings have been proposed and assessed in integrated manner in order to improve the energy efﬁciency and visual comfort in new or existing ofﬁce buildings. Ofﬁce rooms facing south, east, north and west have been simulated for cold climate, by varying glazed areas and proposed glazing and shading alternatives. Results have been calculated, compared and analyzed in terms of the energy consumptions, energy saving potentials, daylight autonomy, useful daylight illuminance and discomfort glare free time, for each of the combina-tions. Simulation results show that the choice of glazing and shading alternatives can have substantial impact on energy and visual performances of the ofﬁce space. Regardless of façade orientation, the max-imum energy saving is achieved for a window-to-wall ratio (WWR) of 30%. Saving potential decreases signiﬁcantly for larger glazed area and for each façade orientation. For all façade orientations and glazed areas (except for 30% WWR in the north wall), a bare low-e coated double glazing (U = 1.616 W/m2 K, SHGC = 0.209, sv = 0.301) is found to be the most energy efﬁcient choice. For 30% north glazing, the energy efﬁciency can be maximized with a different bare low-e coated double glazing (U = 1.628 W/m2 K, SHGC = 0.370, sv = 0.581). Moreover, glare affected time, daylight autonomy and useful daylight illuminance in the ofﬁce spaces with these glazing choices are estimated P50%, between 46% and 99%and in the range of 53–88% respectively. Also, the visual comfort can further be improved just by deploy-ing even a highly transparent fabric (50% transmittance, 20% reﬂectance, 45% average openness) as an interior roller shade with these glazing choices.
Identifying factors that affect the probability of being cured from MDR-TB disease, KwaZulu-Natal, South Africa : a competing risks analysis
(Scientific Research Publishing, Inc., 2022) Mbona, Sizwe Vincent; Mwambi, Henry; Chifurira, Retius
Four decentralised sites are located in rural areas and one centralised hospital in KwaZulu-Natal province, South Africa. Objective: To analyse risk factors associated with multidrug-resistant tuberculosis (MDR-TB) using com peting risks analysis. Understanding factors associated with MDR-TB and obtaining valid parameter estimates could help in designing control and in tervention strategies to lower TB mortality. Method: A prospective study was performed using a competing risk analysis in patients receiving treatment for MDR-TB. The study focused on 1542 patients (aged 18 years and older) who were diagnosed of MDR-TB between July 2008 and June 2010. Time to cure MDR-TB was used as the dependent variable and time to death was the com peting risk event. Results: The Fine-Gray regression model indicated that base line weight was highly significant with sub-distribution hazard ration (SHR) = 1.02, 95% CI: 1.01 - 1.02. This means that weight gain in a month increased chances of curing MDR-TB by 2%. Results show that lower chances to cure MDR-TB were among patients between 41 to 50 years compared to those pa tients who were between 18 to 30 years old (SHR = 0.80, 95% CI: 0.61 - 1.06). The chances of curing MDR-TB in female patients were low compared to male patients (SHR = 0.84, 95% CI = 0.68 - 1.03), however this was not sig nificant. Furthermore, HIV negative patients had higher chances to cure MDR-TB (SHR = 1.07, 95% CI: 0.85 - 1.35) compared to HIV positive pa tients. Patients who were treated in the decentralised sites had lower chances to be cured of MDR-TB (SHR = 0.19, 95% CI: 0.07 - 0.54) as compared to pa tients who were treated in the centralised hospital. Conclusion: Identifying key factors associated with TB and specifying strategies to prevent them can reduce mortality of patients due to TB disease, hence positive treatment out comes leading to the goal of reducing or end TB deaths. Urgent action is re quired to improve the coverage and quality of diagnosis, treatment and care for people with drug-resistant TB.
Irrigation water and microbiological safety of fresh produce : South Africa as a case study : a review
(Academic Journals, 2012-09-11) Ijabadeniyi, Oluwatosin Ademola; Buys, E. M.
Irrigation water is perhaps the leading pre-harvest source of contamination of fresh produce in the world. In this review, the impact of contaminated surface irrigation water on bacterial contamination of fresh produce was examined. Some practical solutions to prevent or reduce this challenge were also considered. In South Africa, fruit and vegetables are produced on a large scale by commercial farmers who depend on surface water for their cultivation. However, the surface water, that is, rivers- has been reported to be heavily contaminated with Escherichia coli and feacal coliforms. There is a concern that contaminated surface water used for irrigation may contaminate fresh vegetables which may also have a negative effect on the export of vegetables to the EU and USA. Consumption of vegetables contaminated with foodborne pathogens presents a public health risk especially in countries like South Africa that has more than 5 million people with immune-system compromised diseases such as HIV and tuberculosis. Other groups of people that may be negatively affected because of the contaminated surface water are those who are directly and indirectly associated with the production of fresh vegetables such as pickers, handlers, packers and farmers that participate in the production of vegetables during pre-harvest and post-harvest. Prevention of contamination of fresh produce from both pre-harvest and post-harvest sources especially irrigation water still remains the only effective way to protect the public. However, for this to occur, every stakeholder in the production industry must have a culture of food safety.
Molecular dynamics simulation of chitinase I from Thermomyces lanuginosus SSBP to ensure optimal activity
(Taylor and Fancis Online, 2016-09-22) Khan, Faez Iqbal; Bisetty, Krishna; Gu, Ke-Ren; Singh, Suren; Permaul, Kugen; Hassan, Md. Imtaiyaz; Wei, Dong-Qing
The fungal chitinase I obtained from Thermomyces lanuginosus SSBP, a thermophilic deuteromycete, has an optimum growth temperature and pH of 323.15 K and 6.5, respectively. This enzyme plays an important task in the defence mechanism of organisms against chitin-containing parasites by hydrolysing β-1, 4-linkages in chitin. It acts as both anti-fungal and biofouling agents, with some being thermostable and suitable for the industrial applications. Three-dimensional model of chitinase I enzyme was predicted and analysed using various bioinformatics tools. The structure of chitinase I exhibited a well-defined TIM barrel topology with an eight-stranded α/β domain. Structural analysis and folding studies at temperatures ranging from 300 to 375 K using 10 ns molecular dynamics simulations clearly showed the stability of the protein was evenly distributed even at higher temperatures, in accordance with the experimental results. We also carried out a number of 20 ns constant pH molecular dynamics simulations of chitinase I at a pH range 2–6 in a solvent. This work was aimed at establishing the optimum activity and stability profiles of chitinase I. We observed a strong conformational pH dependence of chitinase I and the enzyme retained their characteristic TIM barrel topology at low pH.
Pre-service mathematics teachers’ mental constructions of the determinant concept
(Kamla-Raj, 2016) Ndlovu, Zanele; Brijlall, Deonarain
This study aims to reveal the nature of mental constructions made by pre-service teachers when learning the determinant concepts and to contribute to APOS theory (Action, Process, Object and Schema) in terms of instructional strategies. This is guided by the belief that understanding the mental constructions the students make when learning mathematical concepts leads to improved instructional methods. The data was collected through a structured activity sheet and interviews. The findings revealed that the mental constructions made by pre-service teachers in most cases do concur with the preliminary genetic decompositions, and that many pre-service teachers are operating at an action/process stages, with the exception of the few operating at an object stage. It also revealed that many students could carry procedures effectively, even if the meaning of the concept is not constructed, which indicates that students mainly possess procedural knowledge of the determinant concept.
Role of N-terminal residues on folding and stability of C-phycoerythrin : simulation and urea-induced denaturation studies
(Taylor and Fancis, 2013) Anwer, Khalid; Sonani, Ravi; Madamwar, Datta; Singh, Parvesh; Khan, Faez; Bisetty, Krishna; Ahmad, Faizan; Imtaiyaz Hassan, M. D.
The conformational state of biliproteins can be determined by optical properties of the covalently linked chromophores. Recently determined crystal structure of truncated form of α-subunit of cyanobacterial phycoerythrin (αC-PE) from Phormidium tenue provides a new insight into the structure–function relationship of αC-PE. To compare their stabilities, we have measured urea-induced denaturation transitions of the full length αC-PE (FL-αC-PE) and truncated αC-PE (Tr-αC-PE) followed by observing changes in absorbance at 565 nm, ﬂuorescence at 350 and 573 nm, and circular dichroism at 222 nm as a function of [urea], the molar concentration of urea. The transition curve of each protein was analyzed for ΔGD0, the value of Gibbs free energy change on denaturation (ΔGD) in the absence of urea; m, the slope (=∂ΔGD/∂[urea]), and Cm, the midpoint of the denaturation curve, i.e. [urea] at which ΔGD = 0. A difference of about 10% in ΔGD0 observed between FL-αC-PE and Tr-αC-PE, suggests that the two proteins are almost equally stable, and the natural deletion of 31 residues from the N-terminal side of the full length protein does not alter its stability. Furthermore, normalization of probes shows that the urea-induced denaturation of both the proteins is a two-state process. Folding of both structural variants (Tr-αC-PE and FL-αC-PE) of P. tenue were also studied using molecular dynamics simulations at 300 K. The results show clearly that the stability of the proteins is evenly distributed over the whole structure indicating no signiﬁcant role of N-terminal residues in the stability of both proteins.
Thermostable chitinase II from Thermomyces lanuginosus SSBP : Cloning, structure prediction and molecular dynamics simulations
(Elsevier, 2015-04-08) Khan, Faez Iqbal; Govender, Algasan; Permaul, Kugen; Singh, Suren; Bisetty, Krishna
Thermomyces lanuginosus is a thermophilic fungus that produces large number of industrially-signiﬁcant enzymes owing to their inherent stability at high temperatures and wide range of pH optima, including thermostable chitinases that have not been fully characterized. Here, we report cloning, characterization and structure prediction of a gene encoding thermostable chitinase II. Sequence analysis revealed that chitinase II gene encodes a 343 amino acid protein of molecular weight 36.65 kDa. Our study reports that chitinase II exhibits a well-deﬁned TIM-barrel topology with an eight-stranded α/β domain. Structural analysis and molecular docking studies suggested that Glu176 is essential for enzyme activity. Folding studies of chitinase II using molecular dynamics simulations clearly demonstrated that the stability of the protein was evenly distributed at 350 K.
Thermostable chitinase II from Thermomyces lanuginosus SSBP: Cloning, structure prediction and molecular dynamics simulations
(Elsevier, 2015) Khan, Faez Iqbal; Govender, Algasan; Permaul, Kugen; Singh, Suren; Bisetty, Krishna
Thermomyces lanuginosus is a thermophilic fungus that produces large number of industrially-signiﬁcant enzymes owing to their inherent stability at high temperatures and wide range of pH optima, including thermostable chitinases that have not been fully characterized. Here, we report cloning, characterization and structure prediction of a gene encoding thermostable chitinase II. Sequence analysis revealed that chitinase II gene encodes a 343 amino acid protein of molecular weight 36.65 kDa. Our study reports thatchitinase II exhibits a well-deﬁned TIM-barrel topology with an eight-stranded α/β domain. Structural analysis and molecular docking studies suggested that Glu176 is essential for enzyme activity. Folding studies of chitinase II using molecular dynamics simulations clearly demonstrated that the stability of the protein was evenly distributed at 350 K.