Identification and classification of selected endophytic
diazotrophic bacteria The selected EDB were identified by phylogenetic analysis of
the 16S rRNA gene. Total DNA of the bacteria was extracted using a modified potassiumacetate method (Prakamhang et al.
2009) and used as a DNA template in PCR reactions.Amplification of the 16S rRNA gene was performed using a
pair of universal primers, fD1 (5′-AGAGTTTGATCCTGGC TCAG-3′) and rP2 (5′-ACGGCTACCTTGTTACGACTT-3′)
(Weisburg et al. 1991). DNA sequencing was performed by MACROGEN (Korea). The DNA sequences were aligned
and compared to sequences available in GenBank. Phylogenetic tree was constructed by neighbor-joining method
using Mega 4 (Tamura et al. 2007), and confidence levels were estimated for 1,000 replicates by bootstrapping.