Persistence of Bacteroides ovatus under simulated sunlight irradiation

Dong, Shengkun

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https://hdl.handle.net/2142/46872 Copy

Description

Title

Persistence of Bacteroides ovatus under simulated sunlight irradiation

Author(s)

Dong, Shengkun

Issue Date

2014-01-16T18:19:19Z

Director of Research (if dissertation) or Advisor (if thesis)

Nguyen, Thanh H.

Department of Study

Civil & Environmental Eng

Discipline

Environ Engr in Civil Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Bacteroides ovatus
• natural organic matter
• algae
• hydroxyl radicals
• salinity
• simulated sunlight
• Persistence

Abstract

The persistence of Bacteroides ovatus, a human-associated anaerobic fecal contamination indicator bacteria species, was evaluated under simulated sunlight exposure and conditions similar to surface water and seawater. By combining propidium monoazide (PMA) treatment and quantitative polymerase chain reaction (qPCR) detection, the decay rates of B. ovatus were determined in the presence of exogenous photosensitizers and salinity up to 39.5 parts per thousand at 27oC. UVB was found to be important for B.ovatus decay, averaging a four log10 of decay over 6 h of exposure without the presence of extracellular photosensitizers. The addition of NaNO2, an exogenous sensitizer producing hydroxyl radicals, did not significantly change the decay rate of B. ovatus, while the exogenous sensitizer algae organic matter (AOM) slowed down the decay of B. ovatus. At seawater salinity, the decay rate of B. ovatus is either slower than or as fast as that at freshwater salinity. Exogenous photosensitizers did not accelerate B. ovatus decay when being present alone in both low and high salinity solutions. Our study suggests that different B.ovatus persistence exists between light and dark treatment: if it is released into either the water or seawater environment in the evening, 50% of it will still be alive by the next morning; if it is released at noon, only 50% will be alive after mere 5 min of full spectrum irradiation on a clear day.

Graduation Semester

2013-12

Permalink

http://hdl.handle.net/2142/46872

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Copyright 2013 Shengkun Dong

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