Isolation,identification and typification of Alicyclobacillus acidoterrestris and Alicyclobacillus acidocaldarius strains from orchard soil and the fruit processing environment in South Africa

Alicyclobacillus acidoterrestris and Alicyclobacillus acidocaldarius are thermo-acidophilic, non-pathogenic, spore-forming bacteria that can survive the typical heat processing of fruit juices and concentrates. Bacterial endospores then germinate, grow and cause spoilage of acid food products. Species of Alicyclobacillus were isolated from orchard soil and a fruit concentrate production factory in South Africa. Preliminary identification of the isolates was based on morphological, biochemical and physiological properties. Identification at species level was done by PCR amplification using genus-specific primers and 16S ribosomal RNA (rRNA) gene sequencing. The majority of isolates belonged to the species A. acidoterrestris, but A. acidocaldarius was also isolated and identified. As far as we could determine, this is the first report of the isolation of A. acidoterrestris from wash water and soil outside a fruit processing plant, as well as the isolation of A. acidocaldarius from vinigar flies. The genotypic relatedness between strains of A. acidoterrestris and between strains of A. acidocaldarius was determined by RAPD-PCR. Sixteen isolates identified as A. acidoterrestris grouped into four clusters based on RAPD-PCR banding patterns, suggesting that they belong to at least four genotypic groups. Three isolateT:/PGN/ELSEVIER/YFMIC/web/00001155/s identified as A. acidocaldarius gave three unique banding patterns.     

Flexible mass transfer model for water minimization in batch plants

This paper presents the least constrained mass transfer mathematical formulation for freshwater minimization in multipurpose batch chemical processes with central reusable water storage. The mathematical formulation is an extension of the model developed by Majozi [T. Majozi, Wastewater minimization using central reusable water storage in batch processes, Computers and Chemical Engineering Journal 29 (7) (2005) 1631–1646]. In the latter model four scenarios were considered with various limitations or constraints. In the scenario presented in this paper only the mass load is fixed, whilst both the quantity of water used in a particular operation and outlet concentration are allowed to vary. In essence, fixing the mass load is more representative of the practical case. A solution procedure for the resultant nonconvex mixed integer nonlinear programming (MINLP) model is also presented. The solution procedure first involves reformulating the MINLP into a relaxed linear model (MILP). The MILP is first solved, the solution of which forms a feasible starting solution for the MINLP. Presented are two illustrative examples.     

A comparison of mebendazole and albendazole in treating children with Trichuris trichiura infection in Durban, South Africa

OBJECTIVE: To compare the efficacy of mebendazole 500 mg and albendazole 400 mg single-dose treatments of Trichuris trichiura infection in children in the Durban area of KwaZuluNatal, South Africa. DESIGN: A single-blind randomised trial in children with a documented moderate infection of T. trichiura. Ova were counted in stool specimens before and 10 days after treatment by the formal-ether concentration method. SETTING: Two shelters for abandoned and orphaned children in Durban. PARTICIPANTS: Ninety-six children aged between 2 and 12 years. OUTCOME MEASURES: The number of children who showed reduced T. trichiura ova counts after the treatments, and reductions in ova counts, both expressed as percentages. Statistical analysis using the Wilcoxon 2-sample test and the chi-square test. RESULTS: Eighty-two children completed the trial; 42 received mebendazole and 40 albendazole. Of the mebendazole group 85% showed a reduction in T. trichiura ova count, compared with 75% of children who received albendazole. Mebendazole treatment was associated with a median percentage reduction in ova count of 72.2%, which significantly exceeded the 44.1% reduction after albendazole (P = 0.024). CONCLUSION: The mebendazole 500 mg single-dose therapy was more efficacious than the albendazole 400 mg single-dose therapy in treating T. trichiura infection in these children.     

Antimicrobial resistance of bacterial flora associated with bovine products in South Africa.

The administration of subtherapeutic doses of antibiotics to livestock introduces selective pressures that may lead to the emergence and dissemination of resistant bacteria. This study determined the antibiotic-resistance spectra of the microbial flora found on freshly slaughtered and retail beef and in unpasteurized and pasteurized packaged milk. Staphylococci, Enterobacteriaeae, and isolates from total aerobic plate counts were tested for resistance to vancomycin, streptomycin, methicillin, tetracycline, and gentamicin using the disc diffusion susceptibility test and resistance to penicillin was determined by using oxacillin. A larger proportion of resistance to most antibiotics, except for vancomycin, was displayed by isolates from abattoir samples. The incidence of multiple antibiotic resistance (MAR) pathogenic bacteria is also higher in the abattoir. Resistance genes lost because of lack of selective pressure or resistant flora being replaced by more sensitive flora during processing is the reason for the lower incidence of MAR pathogenic bacteria among retail samples. These resistant bacteria can be transferred to humans through the consumption of rare or raw beef and unpasteurized milk, thus rendering the resultant food-related infections difficult to treat. The present findings clearly demonstrate that antibiotic-resistant bacteria in beef and milk pose a serious problem in South Africa.     

Isolation and identification of Alicyclobacillus acidocaldarius by 16S rDNA from mango juice and concentrate

In this study we investigate the spoilage of ultra high temperature UHT mango juice as well as a carbonated fruit juice blend to identify organisms contributing to the spoilage. The mango concentrate, the final product, as well as the other ingredients used during manufacturing, were tested for the presence of Alicyclobacillus by polymerase chain reaction (PCR) and sequencing analyses. Microbiological examination of the mango pureé and spoiled fruit juices, using YSG agar [yeast extract 2 g, glucose 1 g, soluble starch 2 g, pH 3.7 (adjust with 2N H₂SO₄), H₂O 1000 mL, bacto agar 15 g] incubated at 55 °C, detected sporeforming, acid dependent and thermotolerant bacteria. The hyper variable region of the 16S rDNA was amplified. The nucleotide sequence of the PCR fragments was determined using the ABI Prism 310 automated DNA sequencer and the collected sequencing data were analysed and compared with the non‐redundant database using NCBI‐BLAST. Alicyclobacillus acidocaldarius were isolated and identified by 16S rDNA gene sequences analyses. The results indicated that the mango purèe, as well as the final product of mango juice and the fruit juice blend, were positive for Alicyclobacillus. The preventative measures of low pH, pasteurization of mango juice and the subsequent use of aseptic packaging were not regarded as sufficient to prevent the outgrowth of Alicyclobacillus spoilage organisms.     

Prototype Line Crawler for Power Line Inspection

In South Africa, electricity is supplied through thousands-of-kilometers of overhead power cables, which is owned by Eskom the national energy supplier. Currently monitoring of these overhead power cables are done by means of helicopter inspection flights and foot patrols, which are infrequent and expensive. In this paper, the authors present the design of a prototype power line crawler （inspection robot） for the monitoring of these overhead power lines in South Africa. The designed prototype power line crawler is capable of driving on the wire, balancing on the wire and is capable of maneuvering past certain obstacles found on the overhead power cables. The prototype power line crawler is designed to host a monitoring system that monitors the power line as the inspection robot drives on it. Various experimental tests were performed and are presented in this paper, showing the capability of performing these tasks. This prototype inspection robot ensures a platform for future development in this area.     

ANN-DT: an algorithm for extraction of decision trees fromartificial neural networks

Although artificial neural networks can represent a variety of complex systems with a high degree of accuracy, these connectionist models are difficult to interpret. This significantly limits the applicability of neural networks in practice, especially where a premium is placed on the comprehensibility or reliability of systems. A novel artificial neural-network decision tree algorithm (ANN-DT) is therefore proposed, which extracts binary decision trees from a trained neural network. The ANN-DT algorithm uses the neural network to generate outputs for samples interpolated from the training data set. In contrast to existing techniques, ANN-DT can extract rules from feedforward neural networks with continuous outputs. These rules are extracted from the neural network without making assumptions about the internal structure of the neural network or the features of the data. A novel attribute selection criterion based on a significance analysis of the variables on the neural-network output is examined. It is shown to have significant benefits in certain cases when compared with the standard criteria of minimum weighted variance over the branches. In three case studies the ANN-DT algorithm compared favorably with CART, a standard decision tree algorithm.     

The growth and characterization of (211) and (133) Oriented (Hg,Cd)Te epilayers (211)B GaAs by organometallic vapor phase epitaxy

The growth of CdTe buffer layers on (211)B GaAs substrates by organometallic vapor phase epitaxy (OMVPE) was studied, and it was found that, depending on the growth conditions, either the (211) or (133) epitaxial orientation could be formed. In some cases, an epilayer showing a mixed (211) and (133) orientation was also observed. The influence of several growth parameters on the orientation of the CdTe layer was investigated, and it was found that the Te/Cd ratio, together with the growth temperature, have the most significant effect in determining the epilayer orientation. From these results, it was then possible to select nominally optimized growth conditions for CdTe buffer layers of both orientations. (Hg,Cd)Te layers of the same orientations could then be grown and characterized. Although double crystal x-ray diffraction measurements indicated a somewhat better crystalline perfection in the (133) (Hg,Cd)Te layers, these layers showed a poor surface morphology compared to the (211) orientation. Measurement of etch pit densities also indicated defect densities to be typically half an order of magnitude higher in the (133) orientation. Diodes were formed by ion implantation in both orientations and significantly better results were obtained on the (211) (Hg,Cd)Te layers.     

Prototype Monitoring System for Power Line Inspection by Means of a PandaBoard

The national energy supplier （Eskom in South Africa） supplies electricity through thousands-of-kilometers of overhead power lines. The current methods of inspection of these overhead power lines are infrequent and expensive. In this paper, the authors present the development of a prototype monitoring system for power line inspection in South Africa. The developed prototype monitoring system collects data （information） from the overhead power lines, is remotely accessible and fits into a power line robot. The prototype monitoring system makes use ofa PandaBoard （SBC） with GPS receiver and 5 MP camera to collect data. Hardware fatigue is the biggest problem faced on the overhead power lines and is captured by means of the 5 MP camera and is displayed on a website hosted by the PandaBoard via Wi-Fi. The monitoring system has low power consumption, is light weight, compact and easily collects data. The data obtained from the prototype monitoring system was satisfactory and provides an improved solution for monitoring power lines for Eskom in South Africa.     

Development of an Internal Amplification Control Using Multiplex PCR for the Detection of Listeria monocytogenes in Food Products

The bacterial pathogen Listeria monocytogenes is responsible for listeriosis, a food-borne disease, which may result in severe illness and possible death. Large outbreaks of listeriosis have been associated with food products including soft cheeses and ready to eat food products. Polymerase chain reaction (PCR) is a molecular identification method for food-borne pathogens; however, a drawback of this method is that false-positive or false-negative results may occur. To validate the accuracy of the PCR as a powerful molecular tool for pathogen detection, it is important that false-negative results be distinguishable from true-negative PCR results. The aim of this study was to design and include an internal amplification control (IAC) within the PCR to coamplify with L. monocytogenes in order to identify false-negative results of L. monocytogenes from ostrich meat and camembert cheese samples. The IAC had to be incorporated into the PCR without loss of specificity and sensitivity on the detection limit of L. monocytogenes and was developed and tested for use in a multiplex PCR detection system. A region of the pUC19 plasmid was selected as the IAC for this study. The optimal concentration at which pUC19 would coamplify with L. monocytogenes was determined to be 0.001 pg/μL. Following an enrichment procedure, the minimum number of organisms detected in a spiked food sample by the PCR was 8 CFU/mL L. monocytogenes; the same detection limit was attained when the pUC19 IAC was included in the PCR. An optimal pUC19 IAC concentration increased the reliability of the PCR for food diagnostic purposes.