The bacterial communities of Tuber aestivum: preliminary investigations in Molise region, Southern Italy

Purpose Truffles are colonized by a complex microbial community of bacteria, yeasts, and filamentous fungi, whose role has not yet been fully understood. The main purpose of the research was to characterize the bacterial communities associated with Tuber aestivum Vittad. fruiting bodies collected from natural truffle grounds in the Molise region (Southern Italy). Despite it is one of the Italian richest areas of truffles, little is known about truffles in Molise. Methods Six ripe fruiting bodies of Tuber aestivum Vittad. and six soil samples were collected in July 2018 at Villa San Michele in the municipality of Vastogirardi, Molise region. Then, soil and truffle microbial communities were analyzed through 16S rRNA gene sequencing on the Illumina MiSeq platform and bioinformatics analyses. Results Consistently with previous studies, the main phyla retrieved in the investigated ascocarps were Proteobacteria and Actinobacteria, with the genus Bradyrhizobium particularly represented. Nevertheless, significant differences between soil and truffle microbiota and an unexpected heterogeneity across truffles were observed. It is likely that a specific recruitment of bacteria from soil to ascocarps occurs during the truffle formation and that local-scale factors play an important role in determining the structure of the investigated truffle microbial communities. Conclusion Although further analyses (based on a larger soil and truffle sample size and aimed at defining in more detail microbial diversity, soil physical and chemical properties, microclimatic conditions, and vegetation) are required to better understand which are these factors and how they could influence the composition of truffle bacterial communities, this study represents the starting point for a deepened characterization of this economically important product.