1. College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao, Shandong Province, P. R. China;
2. Key Laboratory of Soil Resources and Environment in Qianbei of Guizhou Province, Zunyi Normal University, Zunyi, Guizhou Province, P. R. China;
3. Department of Plant and Microbial Biology, University of California, Berkeley, California, USA;
4. College of Agriculture, Henan University of Science and Technology, Luoyang, Henan Province, P. R. China