Description of environmental samples and DNA extraction.

Twenty-one various environmental samples were collected, including seven soil samples, seven sediment samples, two sludge samples, four water samples, and one plant leaf surface sample. The soil, sediment, and sludge samples were used directly for DNA extraction. For the water samples, 4 to 5 liters of water were filtered through 0.22-μm nitrocellulose filters (Merck Millipore, Billerica, MA), which were then used for genomic DNA extraction. For the leaf surface sample, 3 pieces of lotus leaves were washed with 1 liter of sterile water and then treated as a water sample. Detailed information for all of the samples is shown in Table S7. The environmental samples were stored at −20°C before DNA extraction. Total genomic DNA was extracted using a DNeasy PowerSoil kit (Qiagen, Dusseldorf, Germany) following the manufacturer’s instructions.