Investigation of the Proteomes of the Truffles Tuber albidum pico, T. aestivum, T. indicum, T. magnatum, and T. melanosporum

Abstract

Truffles of the Tuber species are known as expensive foods, mainly for their distinct aroma and taste. This high price makes them a profitable target of food fraud, e.g., the misdeclaration of cheaper truffle species as expensive ones. While many studies investigated truffles on the metabolomic level or the volatile organic compounds extruded by them, research at the proteome level as a phenotype determining basis is limited. In this study, a bottom-up proteomic approach based on LC-MS/MS measurements in data-independent acquisition mode was performed to analyze the truffle species Tuber aestivum, Tuber albidum pico, Tuber indicum, Tuber magnatum, and Tuber melanosporum, and a protein atlas of the investigated species was obtained. The yielded proteomic fingerprints are unique for each of the of the five truffle species and can now be used in case of suspected food fraud. First, a comprehensive spectral library containing 9000 proteins and 50,000 peptides was generated by two-dimensional liquid chromatography coupled to tandem mass spectrometry (2D-LC-MS/MS). Then, samples of the truffle species were analyzed in data-independent acquisition (DIA) proteomics mode yielding 2715 quantified proteins present in all truffle samples. Individual species were clearly distinguishable by principal component analysis (PCA). Quantitative proteome fingerprints were generated from 2066 ANOVA significant proteins, and side-by-side comparisons of truffles were done by T-tests. A further aim of this study was the annotation of functions for the identified proteins. For Tuber magnatum and Tuber melanosporum conclusive links to their superior aroma were found by enrichment of proteins responsible for sulfur-metabolic processes in comparison with other truffles. The obtained data in this study may serve as a reference library for food analysis laboratories in the future to tackle food fraud by misdeclaration of truffles. Further identified proteins with their corresponding abundance values in the different truffle species may serve as potential protein markers in the establishment of targeted analysis methods. Lastly, the obtained data may serve in the future as a basis for deciphering the biochemistry of truffles more deeply as well, when protein databases of the different truffle species will be more complete.

Food authentication: truffle species classification by non-targeted lipidomics analyses using mass spectrometry assisted by ion mobility separation

“…For this reason, research efforts at various cellular levels have been massively advanced in recent years. For example, there are approaches to detect truffle species using genomics-, [7][8][9][10][11] proteomics- [12][13][14] or isotopolomics-based [15][16][17][18] methods. However, all of these approaches are quite time-consuming or require special laboratory infrastructure.…”

From Nontargeted to Targeted Analysis: Feature Selection in the Differentiation of Truffle Species (Tuber spp.) Using 1H NMR Spectroscopy and Support Vector Machine

“…Since clear identification of truffle fruiting bodies under the microscope is challenging and difficult and thus requires a lot of expertise and experience, determining truffle species by PCR amplification or other genomics based methods ,− are possible. Proteomics approaches − or isotopolomics based methods are also feasible options. − But they all require a sophisticated laboratory environment and end up being time-consuming and expensive. Therefore, there is a requirement for further analytical methods to distinguish morphologically similar truffle species.…”

Comparative study of characteristic compounds of three species of truffle

“…Due to its distinct aroma and great nutritional content, a truffle is a tasty, wild edible mushroom that is well-known around the world [1,2]. It has a number of advantageous components, including amino acids, organic acids, and other metabolites, which have pharmacological effects on boosting immunity, decreasing blood pressure, fighting tumors, acting as an antioxidant, and more [3][4][5][6][7]. It is estimated that there are as many as 180 species of truffle in the world, and more than 60 species have been reported in China [8].…”