Free Amino Acids in Three <i>Pleurotus</i> Species Cultivated on Agricultural and Agro-Industrial By-Products

• Main Authors: Dimitra Tagkouli, Andriana Kaliora, Georgios Bekiaris, Georgios Koutrotsios, Margarita Christea, Georgios I. Zervakis, Nick Kalogeropoulos
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Molecules
• Subjects: <i>Pleurotus</i> mushrooms; free amino acids; GABA; bitter amino acids; sweet amino acids; monosodium glutamate-like amino acids
• Online Access: https://www.mdpi.com/1420-3049/25/17/4015

Previous studies have demonstrated the feasibility of employing by-products of the olive and wine sectors for the production of <i>Pleurotus</i> mushrooms with enhanced functionalities. In this work we investigated the influence of endogenous and exogenous factors on free amino acids (FAAs) profile of <i>Pleurotus ostreatus</i>, <i>P. eryngii</i> and <i>P. nebrodensis</i> mushrooms produced on wheat straw (WS), alone or mixed with grape marc (GM), and on by-products of the olive industry (OL). Overall, 22 FAAs were determined in substrates and mushrooms, including all the essential amino acids, the neurotransmitter γ-aminobutyric acid (GABA) and ornithine. On a dry weight (dw) basis, total FAAs ranged from 17.37 mg/g in <i>P. nebrodensis</i> to 130.12 mg/g in <i>P. ostreatus</i> samples, with alanine, leucine, glutamine, valine and serine predominating. Similar distribution patterns were followed by the monosodium glutamate (MSG)-like, sweet and bitter FAAs. Significant differences in FAAs level were observed among the species examined and among the cultivation substrates used. Principal Component Analysis (PCA) performed on the entire FAAs profile of six <i>Pleurotus</i> strains, clearly separated <i>P. ostreatus</i> from <i>P. eryngii</i> and <i>P. nebrodensis</i>, in accordance to their phylogenetic affinity. This is the first report of FAAs in <i>P. nebrodensis.</i>