Possible involvement of Pseudomonas fluorescens and Bacillaceae in structural modifications of Tuber borchii fruit bodies

Previous studies on Tuber borchii fruit bodies in early maturation stages s uggested a role of bacteria in sporocarp structural modifications. In order to verify this hypothesis, in the present study we investigated by means o f microbial and ultrastructural approaches, the bacterial population of T b orchii sporocarps from intermediate maturation phases to advanced decomposi tion stages, paying particular attention to chitinolytic and cellulolytic b acteria and to their relationships with ascii and ascospores. We found that Pseudomonas fluorescens and spore-forming Bacillaceae, both able to degrad e cellulose and chitin, are present inside the sporocarps in all maturation stages investigated. Moreover, rod-shaped bacteria seem able to erode ascu s walls and colonize the interior of ascii containing mature spores. These results suggest a possible role of these bacteria in the process of ascus o pening. Moreover, the presence of P. fluorescens and Bacillaceae on isolate d mature spores after decontamination suggests an intimate association betw een these bacteria and the ascospores.