Inactivation of faecal indicator micro-organisms in waste stabilisation ponds: interactions of environmental factors with sunlight

Davies‐Colley, Robert J.; Donnison, A.; Speed, D. J.; Ross, Colleen; Nagels, John W.

doi:10.1016/s0043-1354(98)00321-2

Cited by 223 publications

(227 citation statements)

References 26 publications

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“…The first-phase decay rate constant of S. aureus strain Newman was significantly larger under the oxic compared to anoxic conditions, suggesting that oxygen-mediated indirect photoinactivation mechanisms are important for the decay of S. aureus. Such oxygen-mediated mechanisms are generally understood to depend on the generation of ROS that damage the cell through photooxidation, and studies have observed that oxygen increases photoinactivation rates for fecal indicator bacteria in environmental systems (6,17,19). In our experiments, ROS were likely generated by sensitizers inside S. aureus cells (i.e., endogenous sensitizers), because reactors consisted only of clear, simulated seawater seeded with S. aureus.…”

Section: Discussionmentioning

confidence: 92%

“…A number of studies have therefore investigated bacterial photoinactivation in the context of environmental water quality (1)(2)(3)(4)(5)(6)(7), with further studies also focusing on photoinactivation in drinking water treatment (8)(9)(10)(11), photodynamic therapy (12)(13)(14)(15), and wastewater treatment (16)(17)(18)(19)(20). Bacteria can be inactivated by sunlight by direct and indirect mechanisms.…”

mentioning

confidence: 99%

“…The majority of previous work on bacterial photoinactivation mechanisms in aquatic environments has focused on fecal indicator bacteria (FIB), such as enterococci, fecal coliforms, and Escherichia coli (2,5,6,11,19,(22)(23)(24), which are the basis of recreational and drinking water quality monitoring criteria (25) and have served as process indicators for decades. Fewer studies have investigated photoinactivation mechanisms of bacterial pathogens in aquatic environments (13,(26)(27)(28).…”

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confidence: 99%

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Staphylococcus aureus Strain Newman Photoinactivation and Cellular Response to Sunlight Exposure

McClary

Sassoubre

Boehm

2017

Appl Environ Microbiol

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Sunlight influences microbial water quality of surface waters. Previous studies have investigated photoinactivation mechanisms and cellular photostress responses of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, but further work is needed to characterize photostress responses of bacterial pathogens. Here we investigate the photoinactivation of Staphylococcus aureus (strain Newman), a pigmented, waterborne pathogen of emerging concern. We measured photodecay using standard culture-based assays and cellular membrane integrity and investigated photostress response by measuring the relative number of mRNA transcripts of select oxidative stress, DNA repair, and metabolism genes. Photoinactivation experiments were performed in both oxic and anoxic systems to further investigate the role of oxygen-mediated and non-oxygen-mediated photoinactivation mechanisms. S. aureus lost culturability much faster in oxic systems than in anoxic systems, indicating an important role for oxygen in photodecay mechanisms. S. aureus cell membranes were damaged by sunlight exposure in anoxic systems but not in oxic systems, as measured by cell membrane permeability to propidium iodide. After sunlight exposure, S. aureus increased expression of a gene coding for methionine sulfoxide reductase after 12 h of sunlight exposure in the oxic system and after 6 h of sunlight exposure in the anoxic system, suggesting that methionine sulfoxide reductase is an important enzyme for defense against both oxygen-dependent and oxygen-independent photostresses. This research highlights the importance of oxygen in bacterial photoinactivation in environmentally relevant systems and the complexity of the bacterial photostress response with respect to cell structure and transcriptional regulation.IMPORTANCE Staphylococcus aureus is a pathogenic bacterium that causes gastrointestinal, respiratory, and skin infections. In severe cases, S. aureus infection can lead to life-threatening diseases, including pneumonia and sepsis. Cases of communityacquired S. aureus infection have been increasing in recent years, pointing to the importance of considering S. aureus transmission pathways outside the hospital environment. Associations have been observed between recreational water contact and staphylococcal skin infections, suggesting that recreational waters may be an important environmental transmission pathway for S. aureus. However, prediction of human health risk in recreational waters is hindered by incomplete knowledge of pathogen sources, fate, and transport in this environment. This study is an in-depth investigation of the inactivation of a representative strain of S. aureus by sunlight exposure, one of the most important factors controlling the fate of microbial contaminants in clear waters, which will improve our ability to predict water quality changes and human health risk in recreational waters.KEYWORDS Staphylococcus aureus, coastal waters, enterococci, fecal indicator bacteria, photoinactivation

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Section: Discussionmentioning

confidence: 92%

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confidence: 99%

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confidence: 99%

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Staphylococcus aureus Strain Newman Photoinactivation and Cellular Response to Sunlight Exposure

McClary

Sassoubre

Boehm

2017

Appl Environ Microbiol

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“…radiation but the results presented here show that they were the most sensitive at the highest irradiation, as reported by other authors (Sinton et al 1999). Sunlight may thus contribute to bacteriophage inactivation, mainly through photo-oxidation catalysed by exogenous photosensitizers (Davies-Colley et al 1999).…”

Section: Discussionmentioning

confidence: 99%

Removal and inactivation of indicator bacteriophages in fresh waters

et al. 2002

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Aims:The removal and inactivation of faecal coliform (FC) bacteria, enterococci (ENT), sulphite-reducing clostridia (SRC), somatic coliphages, F-specific RNA bacteriophages and bacteriophages infecting Bacteroides fragilis in fresh waters. Methods and Results: Removal was studied in two areas of a river. The results showed different removal of each group of microbes. Faecal coliform bacteria were removed faster than any other, whereas SRC and bacteriophages infecting Bact. fragilis were the most persistent. Inactivation was measured by 'in situ' experiments, which showed significant differences in survival of the different groups of bacterial and bacteriophage indicators. The SRC and bacteriophages were more resistant than faecal coliforms and enterococci, with the exception of F-specific RNA bacteriophages in the summer. Inactivation experiments with pure cultures of bacteriophages confirmed that phage B40-8 of Bact. fragilis was the most resistant. Conclusions: Bacteria and bacteriophages show different resistance to natural inactivation. The use of phages allows information to be obtained in addition to that provided by bacterial indicators. Somatic coliphages and phages infecting Bact. fragilis might supply that indicator function. Significance and Impact of the Study: Confirmation was obtained that bacteriophages provided additional information to that provided by bacterial indicators to monitor the natural inactivation of viruses and/or pathogens.

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“…In contrast, the response of the E. coli to UV-A and PAR was similar and a longer term exposure was required to reduce the activity. Viruses have also been shown to be inactivated by solar radiation, but to a lesser degree than bacteria (Davies-Colley, 1999;Stinton, 2002).…”

Section: Sunlight and Water Claritymentioning

confidence: 99%