Nicole Chou              May.11.2010
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Nicole Chou May.11.2010. Nicole Chou May.11.2010. Nicole Chou May.11.2010. Global Water Situation. Water Scarcity. Billion people have no access to an improved water supply and far more lack access to safe water. SODIS (Solar Water Disinfection).

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Nicole Chou May.11.2010

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Nicole Chou May.11.2010

Nicole Chou May.11.2010

Nicole Chou May.11.2010

Global Water Situation

Water Scarcity

Billion people have no access to an improved water supply and far more lack access to safe water.

SODIS (Solar Water Disinfection)

SODIS is a low -cost simple household water treatment method .

Expose drinking water in plastic bottle to sunlight for more than 6 hours.

 Mainly use solar radiation (UVA specific)

 Synergistic effect will occur if water temperature rise above 50 oC

** A positive impact on health has been documented in several epidemiological field studies. For example, In India, where a total 40% of diarrhea diseases and 50% of severe diarrhea episodes were prevented by use of SODIS.

Purpose Of This Research

- To measure the effectiveness of SODIS

 By define the inactivation pattern of mechanisms.

To define the ability of survive and repair damage

- To confirm that temperature is not predominant factor in the elimination of bacteria.

Materials and Methods

  • Enteric Bacterium

    - Gram-negative rod shape bacteria. Includes

    - Eschericia coli (pathogenic strains)

    - Salmonella

    - Shigella

    - Transmission route: Fecal-oral route

    * E.coli K-12 MG1655 Cells.

    Stationary phase cells .

Materials and Methods

  • Multi-parameter flow cytometry

Materials and Methods

  • Fluorescence stain


  • Culturability


Aerobic incubation VS. Anaerobic Incubation



  • Total [ATP]


  • Efflux pump activity


  • Membrane Potential (Depolarization)

Fig 5 d-f

Fig 4 e


  • Membrane Integrity

Fig 5 g-i

Fig 4 f


  • Glucose uptake ability


  • Syto 9 vs. Culturability


  • Syto 9 vs. Membrane potential (Fig 5e & h)


  • Inactivation Pattern

[ATP] decrease

Inactivation of Efflux pump

Loss of Culturability

Loss of membrane potential

Glucose uptake rate decrease

Loss of membrane integrity

Bosshard et al.,2009


  • Subsequent dark storage of Salmonella typhimurium

Bosshard et al.,2009


  • Subsequent dark storage of Shigella flexneri

Bosshard et al.,2009


  • Inactivation mechanism

  • Rapidly [ATP] and inactivation of Efflux pump activity

     Due to damaged on respiratory chain

     PyKF (Pyruvate Kinase) is a direct target


Repair and regrowth

- Viability test were carry out 5 days after irradiation.

 No regrowth or recovery.

 Significant decrease in all measured cellular functions

** This indicates that damaged that caused by UVA light is irreversible.

**The re-grown of permeabilized cells has never been shown


  • SODIS and artificial UVA light kill enteric bacteria by inactivation of the respiratory chain and subsequent exhaustion of ATP.

  • Split exposure reduce the light dose required for inactivation.

  • Temperature is not a predominant factor in the SODIS method.

SODIS Demonstration


Michael Berney, Hans-Ulrich Weilenmann, and Thomas Egli Flow-cytometric study of vital cellular functions in Escherichia coli during solar disinfection (SODIS) Microbiology, Jun 2006; 152: 1719 - 1729.

F. Bosshard, M. Berney, M. Scheifele, H.-U. Weilenmann, and T. EgliSolar disinfection (SODIS) and subsequent dark storage of Salmonella typhimurium and Shigella flexneri monitored by flow cytometryMicrobiology, April 1, 2009; 155(4): 1310 - 1317.

Kenya Sun Water Safer to Drink CNN. David McKenzie. September 1, 2009 <>

SODIS. “SODIS (short for Solar Water Disinfection)" <>

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