Identification and Characterization of Endophytic Diazotrophs Isolated from Cymbopogon caesius and Miscanthus floridulus: Identification and Characterization of Endophytic Diazotrophs Isolated from Cymbopogon caesius and Miscanthus floridulus

In order to investigate the diversity of endophytic diazotrophs in Cymbopogon caesius and Miscanthu floridulus, thirty and thirty-six isolates were obtained respectively from these two forage grasses by using two selective medium without nitrogen sources in combination with acetylene reduction assay. The sixty-six endophytic diazotrophs were assigned to 10 groups (61 strains, at least 3 for each group from I to X) and five ungrouped strains by analysis of SDS-PAGE (dodecyl sulfate sodium salt polyacrylamide gel electrophoresis) patterns of whole-cell protein electrophoresis and IS-PCR (Insertion sequence-based PCR) DNA fingerprinting. 16S rDNA sequencing analysis of representative strains of each group showed that these strains were closely related to Burkholderia cepacia, Enterobacter cloacae, Phytobacter diazotrophicus, Enterobacter asburiae, Herbaspirillum seropedicae, Cronobacter sakazakii, Enterobacter oryzae, Klebsiella pneumoniae, Enterobacter dissolvens, Azospirillum amazonense, and Cronobacter dublinensis, indicating the high diversity of endophytic diazotrophs colonized in the host plants of C. caesius and M. floridulus. The results of physiological and biochemical tests showed that some isolates had the ability of ammonia secreting, indole producing, and phosphorus and potassium dissolving, suggesting the potential application in agricultural practices. Fig 2, Tab 3, Ref 38