Comparison of bacterial communities in roots of selected trees with and without summer truffle (Tuber aestivum) ectomycorrhiza

In this study, we examined the effect of the presence of mycorrhiza and ascomata of summer truffle (Tuber aestivum) on the bacterial composition of roots from small trees growing in selected sites of the Nida Basin. Qualitative DNA sequencing methods such as Sanger and next-generation sequencing (NGS) were used.

The Sanger method revealed different bacterial species compositions between the samples where summer truffle ascomata was recorded and control samples. Five genera of bacteria could be distinguished: Bacillus, Erwinia, Pseudomonas, Rahnella and Serratia, among which the most numerous were Pseudomonas (Gammmaproteobacteria class) at 32.9%. The results obtained by the NGS method also showed differences in species composition of the bacteria depending on the study sample. Seven genera of bacteria were distinguished: Rhizorhabdus, Methylotenera, Sphingomonas, Nitrosospira, Streptomyces, Methyloceanibacter and Niastella, which dominated in roots from the truffle sites. Telmatobacter, Roseiarcus, Granulicella, Paludibaculum, Acidipila, Acidisphaera and Aliidongia dominated in roots from the control sites. With the NGS method, it is possible to identify the microbiome of a whole root, while only a root fragment can be analysed by the Sanger method.

These results extend the scope of knowledge on the preferences of certain groups of bacteria associated with truffles and their influence on the formation of ascomata in summer truffles. Our results may also be useful in selecting and monitoring sites that promote ascomata of Tuber aestivum.