Detection and identification of bacterial endosymbionts in arbuscular mycorrhizal fungi belonging to the family gigasporaceae

Intracellular bacteria have been found previously in one isolate of the arb uscular mycorrhizal (AM) fungus Gigaspora margarita BEG 34. In this study, we extended our investigation to 11 fungal isolates obtained from different geographic areas and belonging to six different species of the family Giga sporaceae, With the exception of Gigaspora rosea, isolates of all of the AM species harbored bacteria, and their DNA could be PCR amplified with unive rsal bacterial primers. Primers specific for the endosymbiotic bacteria of BEG 34 could also amplify spore DNA from four species, These specific prime rs were successfully used as probes for in situ hybridization of endobacter ia in G. margarita spores. Neighbor-joining analysis of the 16S ribosomal D NA sequences obtained from isolates of Scutellospora persica, Scutellospora castanea, and G. margarita revealed a single, strongly supported branch ne sted in the genus Burkholderia.