Department of Automation, Xiamen University, Xiamen, Fujian, China.|Bioinformatics Division, TNLIST and Department of Automation, Tsinghua University, Beijing, China.|Department of Automation, Xiamen University, Xiamen, Fujian, China.|Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA.|Bioinformatics Division, TNLIST, and Department of Computer Science and Technology, Tsinghua University, Beijing, China.