Stable Nitrogen and Carbon Isotope Signatures (δ 15N and δ 13C Values in ‰) of Fresh and Preserved Button Mushrooms (Agaricus bisporus) from the German Market

Abstract

Fresh and preserved button mushrooms (Agaricus bisporus) are among the most consumed varieties worldwide. The cultivation is highly optimized and largely based on the use of different compost materials from agricultural wastes as substrates. In this study, we determined the stable carbon (13C) and nitrogen (15N) isotope signatures of the fruiting bodies and used the measured δ values (‰) to obtain indirect information on the medium on which they were grown. The δ 13C values (‰) of the investigated fresh and processed button mushrooms from the German market were quite narrow (δ 13C values −24.8 ± 0.9 ‰, n = 72), which indicated C3 plant materials as carbon sources. Overall high δ 15N values (δ 15N values > 5.5 ‰) of the cultivated mushrooms enabled a differentiation to wild growing saprophytes. Furthermore, the broad range of δ 15N values (Δ=7 ‰) pointed toward a cultivation on compost materials with varying shares of farmyard manure. While only few samples suggested a cultivation on dominantly plant-based substrates, more than 50% of the investigated button mushrooms were related to high shares of animal manures in the compost mixture. Little variation of δ 15N values (‰) in related products collected on subsequent years indicated a high level of standardization of the individual cultivation processes over several years. Analysis of the carbon and nitrogen isotope signatures of cultivated button mushrooms could thus be valuable parameters used for long-term monitoring and controlling purposes.