1. Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu 500-712 Gwangju, Korea, Applied R&D Center, Southern Nevada Water Authority, 1001 S. Valley View Blvd., Las Vegas, Nevada 89125, and USDA-ARS Environmental Microbial Safety Laboratory, Beltsville, Maryland 20705