1. Division of Applied Bioscience and Biotechnology, Institute of Agricultural Science and Technology, College of Agriculture and Life Science, Chonnam National University, Gwangju 500-757, South Korea; Department of Civil and Environmental Engineering, Kwangju University, Gwangju 503-703, South Korea; and Department of Environmental Science and Engineering, Kwangju Institute of Science and Technology, Gwangju 500-712, South Korea