Analysis on the species diversity of cyanobacteria in paddy field by comparison between norm al culture and DGGE method

Segments of 1 6S rDNA genes from cyanobacteria were retrieved from paddy field samples by DNA extraction and polymerase chain reaction(PCR)，and subsequently analyzed by denaturing gradient gel electrophoresis(DGGE)．The cyanobacterial community was analyzed in the rice paddy field by nested PCR using universal 1 6S rDNA primers and subsequently primers targeting cyanobacterial specific regions in the 1 6S rDNA genes．The amplified products were analyzed by denaturing gradient gel electrophoresis(DGGE)．14 dominating bands were excised from the gels and further sequenced and determined by BLAST search against the GenBank database．10 bands were identified as cyanobacteria，representing 6 different cyanobacerial genera．4 of the bands were identified as belonging tO the genus Leptolyngbya，1 tO the genus Nostoc，2 tO the genus Synechococcus，and 1 tO each of the genera Oscillatoria，Chroococcidiopsis and Chamaeaiphon，respectively．The cyanobacterial diversity varied both in the upper and the deeper soil fractions and different sampling points．Lyngbya，Oscillatoria，Chroococcidiopsis and Nostoc were identified under microscope by normal culture method，but can not be identified exactly，indicated that DGGE method can reflect the complex and dynamic of cyanobacteria in the community．