Bacterial communities inhabiting the ascomata of the ectomycorrhizal summer truffle (Tuber aestivum)

Abstract

This paper continues the studies on the role of bacteria in the environment of summer truffle (Tuber aestivum), focusing on ascomata at three sites in the Nida Basin (southern Poland). Bacterial taxa and the number of OTU sequences identified were determined based on analysis of peridium and gleba collected in 2017 and 2018. The aim of the presented work is to learn the structure of bacterial communities associated with the ascomata of the summer truffle T. aestivum forming in specific stands in south Poland and fine roots of surrounding trees. Sanger DNA sequencing, and next-generation sequencing (NGS) were used. NGS sequencing platforms short-read (300 bases) was selected, using a MiSeq Illumina. The Kruskall-Wallis test was used for alpha diversity analysis and the PERMANOVA test for beta diversity. Alpha and beta biodiversity analyzes were performed using various indices (Chao1, Simpson, Shannon, Faith's phylogenetic, observed OTUs, Heip's evenness measure - alpha diversity; UniFrac, Jaccard, Bray–Curtis - beta diversity).The Sanger method identified six bacterial taxa that were dominant in the community: Bacillus (86.7 %), Pseudomonas (51.5 %), Stenotrophomonas (15.5 %), Paenibacillus (7.9 %), Rhizobium (7.3 %), and Chryseobacterium (8.5 %). In contrast, NGS results showed the dominance (at OTUs >10,000) of taxa: Bradyrhizobiaceae, Sphingobacteriaceae, Micrococcaceae, Yersiniaceae, Sphingomonadaceae, Rhizobiaceae, Flavobacteriaceae, and Comamonadaceae. The PERMANOVA test for the Bray-Curtis and Jaccard indices showed dissimilarities between samples from two of the sites with respect to beta diversity. Significant differences were found in the bacterial communities colonizing the ascomata of T. aestivum and in the root communities with T. aestivum ectomycorrhizae the purpose of this study. The results obtained may be helpful in selecting and monitoring sites suitable for the formation of ascomata of T. aestivum.