The neuroactive potential of Grana Padano and Parmigiano Reggiano cheese microbiome
Date:
Abstract: Grana Padano (GP), Trentingrana (TG), and Parmigiano Reggiano (PR) are among the most widely recognised Italian Protected Designation of Origin (PDO) cheeses. Their long ripening process (≥12 months) is characterised by strong proteolysis. During this time, the cheese microbiome plays a chief role in metabolising amino acids, leading to the formation of flavouring and neuroactive compounds. Thus, the present study was designed as a multiomic approach in order to profile the microbiome, the volatilome, and the proteome of GP, TG and PR cheeses. We sampled PDO GP (n=42), TG (n=18), and PR (n=63), and then assessed the microbiome by high-throughput shotgun metagenomic sequencing, the volatile organic compounds (VOCs) by gas chromatography/mass spectrometry (GC/MS), and proteome by liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS). Bioinformatic, statistical, and machine learning analysis were performed to investigate the metagenome, volatilome, and metaproteome. Taxonomic profiles revealed a clustering of PR and TG vs GP, suggesting the existence of two groups of cheeses, as also demonstrated by a supervised machine learning classification model. Functional metagenomic analysis further identified protein–coding genes involved in the biosynthesis of neuroactive molecules, including gamma-aminobutyric acid (GABA), serotonin, catecholamines, acetylcholine, indole-3-propionic acid, and conjugated linoleic acids. The presence of the predicted neurotransmitter peptides was also assessed and quantified. By merging metagenomics, volatilomics, and metaproteomics data, a second supervised machine learning analysis helped to explain those features that were most impactful in predicting the two groups of cheeses. Our results demonstrated that, although GP and TG belong to the same PDO disciplinary, their microbiome strongly differ. In addition, long–ripened cheeses are potential sources of psychobiotics, underscoring their importance in promoting mental well-being