The cultivation of microbes and microscopy techniques as a means to identify microbial communities have severe limitations, since the majority of microbes in the environment are viable but nonculturable. For this reason, the methods of biochemistry and molecular biology that are independent of culturing are being widely used in the studies of microbial ecology. In this paper, fluorescent technique, PCR-based technique, PLFA technique and others to characterize diversity of microorganisms are reviewed. ...