AUTHOR=Li Xiaolin , Zhang Xiaoping , Ye Lei , Kang Zongjing , Jia Dinghong , Yang Lufang , Zhang Bo 

TITLE=LC-MS-Based Metabolomic Approach Revealed the Significantly Different Metabolic Profiles of Five Commercial Truffle Species

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02227

DOI=10.3389/fmicb.2019.02227

ISSN=1664-302X

ABSTRACT=<p>Truffles are ascomycetous ectomycorrhizal fungi that have elevated status in the culinary field due to their unique aroma and taste as well as their nutritional value and potential biological activities. <italic>Tuber melanosporum</italic>, <italic>T. indicum</italic>, <italic>T. panzhihuanense</italic>, <italic>T. sinoaestivum</italic>, and <italic>T. pseudoexcavatum</italic> are five commercial truffle species mainly distributed in Europe or China. In this study, an untargeted metabolomics technology based on an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was applied to analyze the metabolic profiles and variations among these five truffle species. In our results, a total of 2376 metabolites were identified under positive ion mode, of which 1282 had significantly differential amounts and covered 110 pathways or metabolisms. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) revealed a clear separation from each of these five truffles, indicating a significantly different metabolic profile among them, with the biggest difference between <italic>T. melanosporum</italic> and the other four truffles. The differential metabolites covered various chemical categories, and a detailed analysis was performed for nine metabolic categories, including amino acids, saccharides and nucleosides, organic acids, alkaloids, flavonoids, carnitines, phenols and alcohols, esters, and sulfur compounds. For each of the nine categories, most of metabolites predominantly accumulated in <italic>T. melanosporum</italic> compared with the other four truffles. Meanwhile, there were significant differences of the average ion intensity in each category among the five truffles, e.g., higher amounts of amino acids was detected in <italic>T. panzhihuanense</italic> and <italic>T. pseudoexcavatum; T. indicum</italic> contained significantly more carnitines, while there were more alkaloids in <italic>T. melanosporum.</italic> Additionally, some metabolites with biological activities were discussed for each category, such as acetyl-<sc>L</sc>-carnitine, adenine, neobavaisoflavone, and anandamide. Generally, this study may provide the valuable information regarding the variation of the metabolic composition of these five commercial truffle species, and the biological significance of these metabolites was uncovered to explore the metabolic mechanisms of truffles, which would be helpful for further research on the compounds and potential biological functions in truffles that have not yet been investigated.</p>