1. Photoreactivation and dark repair of environmentalE. colistrains following 24 kHz continuous ultrasound and UV-C irradiation
- Author
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Jasjeet Kaur, Suresh D. Pillai, and Raghupathy Karthikeyan
- Subjects
Environmental Engineering ,Ultraviolet Rays ,02 engineering and technology ,Wastewater ,010501 environmental sciences ,Biology ,01 natural sciences ,Bacterial cell structure ,Water Purification ,Microbiology ,Coli strain ,Escherichia coli ,Humans ,Ultrasonics ,Irradiation ,Photolyase ,Effluent ,Feces ,0105 earth and related environmental sciences ,business.industry ,Ultrasound ,General Medicine ,021001 nanoscience & nanotechnology ,Disinfection ,Water Microbiology ,0210 nano-technology ,business ,Metabolic activity - Abstract
In this study, effects of 24 kHz continuous ultrasound and UV-C on inactivation and potential repair of environmental E. coli strains were studied through a culture based method and a metabolic activity assay. Three environmental E. coli strains isolated from fecal samples of feral hog and deer and treated wastewater effluent were studied and compared with a laboratory E. coli strain (ATCC® 10798). Metabolic activity of E. coli cells during the inactivation and repair period was assessed using the AlamarBlue® assay. Transmission electron microscopy assays were also performed to evaluate morphological damage of bacterial cell wall. After 24 h of photoreactivation period, laboratory E. coli strain (ATCC® 10798) reactivated by 30% and 42% in contrast to E. coli isolate from treated wastewater effluent, which reactivated by 53% and 82% after ultrasound and UV-C treatment, respectively. Possible shearing and reduction in cell size of E. coli strains exposed to ultrasound was revealed by transmission electron micrographs. Metabolic activity of E. coli strains was greatly reduced due to morphological damage to cell membrane caused by 24 kHz continuous ultrasound. Based upon experimental data and TEM micrographs, it could be concluded that ultrasound irradiation has potential in advanced water treatment and water reuse applications.
- Published
- 2016
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