Molecular characterization of cellulosolytic-chitinolytic bacteria associated with fruitbodies of the ectomycorrhizal fungus Tuber borchii Vittad.

This study describes a molecular characterization of fluorescent pseudomona ds and spore-forming bacteria isolated from fruitbodies of the ectomycorrhi zal fungus Tuber borchii Vittad. These strains had previously been characte rized for their cellulosolytic and chitinolytic activities and studied for their putative role in facilitating ascus opening and ascospore germination within fruitbodies of T. borchii (Gazzanelli et al., 1999). In the present study, representative pure cultures of these bacteria were genetically cha racterized using amplified ribosomal 16S rRNA gene (rDNA) restriction analy ses (ARDRA). Examination of the ARDRA patterns revealed two different 16S r DNA types among the pseudomonads and three 16S rDNA types among the spore-f orming bacteria. Strains representative of each type were chosen for 16S rD NA sequencing. Phylogenetic analysis of the 16S rDNA sequence placed member s of the pseudomonads in branches belonging to the Pseudomonas fluorescens and P. syrigae lineages of the P. fluorescens cluster, while phylogenetic a nalysis of the spore-forming bacteria placed them in branches belonging to the Bacillus subtilis group, B. cereus group and Paenibacillus spp. These r esults represent one the first attempts to make systematic molecular compar isons and carry out functional studies of the bacteria-fungus-plant symbios es within the ectomycorrhizal fungus T. borchii Vittad.