I am P.hD student in Chungbuk National University and I am studying the endobacteria which live inside arbuscular mycorrhizal fungi spores.

So far, only one obligatory endobacteria (Candidatus Glomeribacter gigasporarum) was isolated from AMF spores and it is candidates in nature ( Bianciotto et al., 2003). Other than that, few other bacterial isolates were obtained from AMF cytoplasm by crushing the spores after surface sterilization or using hypodermic needle method. Are there any possibilities for facultative endobacteria live inside arbuscular mycorrhizal fungi? If so, why does it enter inside the AMF spores, and what benefit do the bacteria or AMF get by this association?