Occurrence, physiological and molecular analysis of endophytic diazotrophic bacteria in gramineous energy plants

Endophytic diazotrophic bacteria could be isolated from the energy plants Pennisetum purpureum, Miscanthus sinensis, Miscanthus sacchariflorus and Spartina pectinata using semisolid nitrogen free media. Higher levels of diazotrophic bacteria were found if no nitrogen fertilizer was applied. The bacteria were characterized on the basis of typical morphology, physiological tests, and the use of phylogenetic oligonucleotide probes. They belong partially to the species Azospirillum lipoferum and Herbaspirillum seropedicae while others supposedly represent a new species of Herbaspirillum. Using PCR-fingerprinting techniques a limited genetic diversity of these isolates was found which may indicate an adaptation to the specific conditions of the interior of these plants.