3.2 PCR amplification, DGGE and phylogenetic profile of actinomycetes based on nifH genes
The PCR products of nifH gene from soil and rice plants roots with the size of fragment DNA ∼360 bp (Fig. 4) were separated using polyacrylamide gel containing 40–65% denaturant. Based on DGGE result, it showed that community structure of nitrogen fixing bacteria in soil samples were more varied than that of the root samples (Fig. 5A). Cluster analysis of community showed that the community of nitrogen fixing bacteria in soil samples were different with roots sample (Fig. 5B). Sequence analysis result showed that bands 1, 2, 3 had 99% similarity with uncultured bacterium clone J50 based on maximum identity from GenBank database. Band 4 was closely related with uncultured bacterium clone clod-38 with 98% of maximum identity, and band 5 was closely related with uncultured bacterium clone BG2.37 with 92% of maximum identity