Abstract：Abstract: Using 16S rDNA-PCR-DGGE, electron microscopy and conventional plating method, an attempt had been made to explore the genetic diversity and phenotype polymorphism of the endophytic bacteria within A.microphylla. Based on 16S rDNA-PCR-DGGE profile it is suggested that there is a complex and divergent bacterial community with Bacillus cereus and its variants as dominant species within Azolla-cyanobacteria association, which was supported by the fact that the endobacterial cells exhibited distinct ultrastructural characteristics in vivo and the bacteria appeared various colonies with different size, shape and colors in vitro. The advantage and limitation of using DGGE in uncovering genetic diversity and the potential role of endophtic bacteria in phylogeny and synchronic evolution among the Azolla, cyanobacteria and bacteria were discussed.
