EMA-qPCR to monitor the efficiency of a closed-coupled solar pasteurization system in reducing Legionella contamination of roof-harvested rainwater

Reyneke, Brandon; Dobrowsky, P. H.; Ndlovu, Thando; Khan, S. Ajmal; Khan, Wesaal

doi:10.1016/j.scitotenv.2016.02.108

Cited by 27 publications

(13 citation statements)

References 46 publications

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“…For each sampling event, 1 L rainwater sample [SOPAS (untreated and pasteurized samples) and SODIS (untreated and treated samples)] was concentrated as outlined in Reyneke et al [20]. The concentrated rainwater samples utilised for Legionella spp.…”

Section: Methodsmentioning

confidence: 99%

“…were detected at the higher pasteurization temperatures (>78 °C), using the Polymerase Chain Reaction (PCR), however the viability of these organisms at temperatures higher than 72 °C was not confirmed. In a follow up study, Reyneke et al [20] then utilised ethidium monoazide bromide quantitative polymerase chain reaction (EMA-qPCR) to verify that viable Legionella spp. were detected in solar pasteurized rainwater samples (>70 °C).…”

Section: Introductionmentioning

confidence: 99%

“…It is well known that Legionella can proliferate at high temperatures [17, 21], however the growth temperature for Legionella is between 25 °C and 45 °C with an optimum temperature of 36 °C [22]. In a recent study conducted by Reyneke et al [20] the research group showed that Legionella spp. are viable at temperatures higher than 70 °C.…”

Section: Introductionmentioning

confidence: 99%

“…Results obtained by Dobrowsky et al [17] and Reyneke et al [20] however, also indicated that significant concentrations of iron (Fe), aluminium (Al), lead (Pb) and nickel (Ni) may have been leaching from the 100 L stainless steel storage tank of the Apollo™ SOPAS system, which may have negatively affected the chemical quality of the treated rainwater. In the current study a new Phungamanzi TM SOPAS system, which was designed and manufactured in South Africa and which consists of a 125 L high grade polyethylene storage tank, was utilised for the solar pasteurization of rainwater.…”

Section: Introductionmentioning

confidence: 99%

“…Ethidium monoazide bromide is a nucleic acid binding dye that can be used to bind to the deoxyribonucleic acid (DNA) of cells (after photoactivation) with damaged and permeable membranes (non-viable cells). The binding of the dye to the DNA prevents PCR amplification of the DNA and thereby leads to a strong signal reduction during qPCR as only the DNA from intact (viable) cells will be amplified [20, 26]. …”

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of solar pasteurization versus solar disinfection for the treatment of harvested rainwater

et al. 2016

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BackgroundNumerous pathogens and opportunistic pathogens have been detected in harvested rainwater. Developing countries, in particular, require time- and cost-effective treatment strategies to improve the quality of this water source. The primary aim of the current study was thus to compare solar pasteurization (SOPAS; 70 to 79 °C; 80 to 89 °C; and ≥90 °C) to solar disinfection (SODIS; 6 and 8 hrs) for their efficiency in reducing the level of microbial contamination in harvested rainwater. The chemical quality (anions and cations) of the SOPAS and SODIS treated and untreated rainwater samples were also monitored.ResultsWhile the anion concentrations in all the samples were within drinking water guidelines, the concentrations of lead (Pb) and nickel (Ni) exceeded the guidelines in all the SOPAS samples. Additionally, the iron (Fe) concentrations in both the SODIS 6 and 8 hr samples were above the drinking water guidelines. A >99% reduction in Escherichia coli and heterotrophic bacteria counts was then obtained in the SOPAS and SODIS samples. Ethidium monoazide bromide quantitative polymerase chain reaction (EMA-qPCR) analysis revealed a 94.70% reduction in viable Legionella copy numbers in the SOPAS samples, while SODIS after 6 and 8 hrs yielded a 50.60% and 75.22% decrease, respectively. Similarly, a 99.61% reduction in viable Pseudomonas copy numbers was observed after SOPAS treatment, while SODIS after 6 and 8 hrs yielded a 47.27% and 58.31% decrease, respectively.ConclusionWhile both the SOPAS and SODIS systems reduced the indicator counts to below the detection limit, EMA-qPCR analysis indicated that SOPAS treatment yielded a 2- and 3-log reduction in viable Legionella and Pseudomonas copy numbers, respectively. Additionally, SODIS after 8 hrs yielded a 2-log and 1-log reduction in Legionella and Pseudomonas copy numbers, respectively and could be considered as an alternative, cost-effective treatment method for harvested rainwater.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Comparative analysis of solar pasteurization versus solar disinfection for the treatment of harvested rainwater

et al. 2016

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Treatment Techniques in Water Harvesting

Reyneke

Waso

Ndlovu

et al. 2021

Handbook of Water Harvesting and Conservation

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Comparison of EMA-, PMA- and DNase qPCR for the determination of microbial cell viability

Reyneke

Ndlovu

Khan

et al. 2017

Appl Microbiol Biotechnol

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Ethidium monoazide (EMA) quantitative polymerase chain reaction (qPCR), propidium monoazide (PMA)-qPCR and DNase treatment in combination with qPCR were compared for the determination of microbial cell viability. Additionally, varying EMA and PMA concentrations were analysed to determine which dye and concentration allowed for the optimal identification of viable cells. Viable, heat treated (70 °C for 15 min) and autoclaved cultures of Legionella pneumophila, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus and Enterococcus faecalis were utilised in the respective viability assays. Analysis of the viable and heat-treated samples indicated that variable log reductions were recorded for both EMA [log reductions ranging from 0.01 to 2.71 (viable) and 0.27 to 2.85 (heat treated)], PMA [log reductions ranging from 0.06 to 1.02 (viable) and 0.62 to 2.46 (heat treated)] and DNase treatment [log reductions ranging from 0.06 to 0.82 (viable) and 0.70 to 2.91 (heat treated)], in comparison to the no viability treatment controls. Based on the results obtained, 6 μM EMA and 50 μM PMA were identified as the optimal dye concentrations as low log reductions were recorded (viable and heat-treated samples) in comparison to the no viability treatment control. In addition, the results recorded for the 6 μM EMA concentration were comparable to the results obtained for both the 50 μM PMA and the DNase treatment. The use of EMA-qPCR (6 μM) may therefore allow for the rapid identification and quantification of multiple intact opportunistic pathogens in water sources, which would benefit routine water quality monitoring following disinfection treatment.

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EMA-qPCR to monitor the efficiency of a closed-coupled solar pasteurization system in reducing Legionella contamination of roof-harvested rainwater

Cited by 27 publications

References 46 publications

Comparative analysis of solar pasteurization versus solar disinfection for the treatment of harvested rainwater

Comparative analysis of solar pasteurization versus solar disinfection for the treatment of harvested rainwater

Treatment Techniques in Water Harvesting

Comparison of EMA-, PMA- and DNase qPCR for the determination of microbial cell viability

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