Summary: Tuber magnatum , an ascomycetous fungus and obligate ectomycorrhizal symbiont, forms hypogeous fruit bodies, commonly called Italian white truffles. The diversity of bacterial communities associated with T. magnatum truffles was investigated using culture‐independent and ‐dependent 16S rRNA gene‐based approaches. Eighteen truffles were classified in three groups, representing different degrees of ascocarp maturation, based on the percentage of asci containing mature spores. The culturable bacterial fraction was (4.17 ± 1.61) × 10 ⁷ , (2.60 ± 1.22) × 10 ⁷ and (1.86 ± 1.32) × 10 ⁶ cfu g ⁻¹ for immature, intermediate and mature ascocarps respectively. The total of bacteria count was two orders of magnitude higher than the cfu g ⁻¹ count. Sequencing results from the clone library showed a significant presence of α ‐Proteobacteria (634 of the 771 total clones screened, c. 82%) affiliated with Sinorhizobium , Rhizobium and Bradyrhizobium spp. The bacterial culturable fraction was generally represented by γ‐ Proteobacteria (210 of the 384 total strains isolated, c. 55%), which were mostly fluorescent pseudomonads. Fluorescent in situ hybridization confirmed that α‐ Proteobacteria (85.8%) were the predominant components of truffle bacterial communities with β‐ Proteobacteria (1.5%), γ‐ Proteobacteria (1.9%), Bacteroidetes (2.1%), Firmicutes (2.4%) and Actinobacteria (3%) only poorly represented. Molecular approaches made it possible to identify α‐ Proteobacteria as major constituents of a bacterial component associated with T. magnatum ascoma, independently from the degree of maturation.

The microbial community associated with ascocarps of the ectomycorrhizal fungus Tuber borchii Vittad. was studied by both cultivation and direct extraction of bacterial 16S rRNA gene (rDNA) sequence approaches. The inner part of six T. borchii ascoma collected in North-Central Italy was used to establish a bacterial culture collection and to extract the total genomic DNA to obtain a library of 16S rDNAs representative of the truffle bacterial community. Most of the isolates were affiliated to the gamma-Proteobacteria, mainly Fluorescent pseudomonads; some isolates were members of the Bacteroidetes group and Gram-positive bacteria, mostly Bacillaceae. The majority of the clones from the library were alpha-Proteobacteria showing significant similarity values, of greater than 97%, with members of the Sinorhizobium/Ensifer Group, Rhizobium and Bradyrhizobium spp. not previously identified as Tuber-associated bacteria. Only a few bacterial strains belonging to this bacterial subclass were found in the culture collection and isolated on a medium specific for Rhizobium-like organisms. A few clones were members of the beta- and gamma-Proteobacteria; as well as low and high G+C Gram-positive bacteria. Our findings clearly indicate that a dual approach increases the information obtained on the structural composition of a truffle bacterial community as compared to that derived via cultivation or direct recovery of 16S rDNA sequences alone.

In recent years, the improvement in health and social conditions has led to an increase in the average lifespan. Since aging is the most important risk factor for the majority of chronic human diseases, the development of therapies and intervention to stop, lessen or even reverse various age-related morbidities is an important target to ameliorate the quality of life of the elderly. The gut microbiota, that is, the complex ecosystem of microorganisms living in the gastrointestinal tract, plays an important role, not yet fully understood, in maintaining the host’s health and homeostasis, influencing metabolic, oxidative and cognitive status; for this reason, it is also named “the forgotten endocrine organ” or “the second brain”. On the other hand, the gut microbiota diversity and richness are affected by unmodifiable factors, such as aging and sex, and modifiable ones, such as diet, pharmacological therapies and lifestyle. In this review, we discuss the changes, mostly disadvantageous, for human health, induced by aging, in microbiota composition and the effects of dietary intervention, of supplementation with probiotics, prebiotics, synbiotics, psychobiotics and antioxidants and of physical exercise. The development of an integrated strategy to implement microbiota health will help in the goal of healthy aging.