However,in several cases the 16S rRNA based-phylogeny of the isolates revealed a high level of identity with species not described as diazotrophic nor containing nitrogenase - encoding genes (e.g.A. spanius ,M.arborescens , S.paucimobilis,PS.libanensis and PS.viridiflava),suggesting a wider range of nitrogenase-containing species than previously known.