Stable Nitrogen and Carbon Isotope Signatures (δ15N andδ13C Values in parts per thousand) of Fresh and Preserved Button Mushrooms(Agaricus bisporus)from the German Market

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 (C-13) and nitrogen (N-15) isotope signatures of the fruiting bodies and used the measured delta values (parts per thousand) to obtain indirect information on the medium on which they were grown. The delta C-13 values (parts per thousand) of the investigated fresh and processed button mushrooms from the German market were quite narrow (delta C-13 values -24.8 +/- 0.9 parts per thousand, n = 72), which indicated C(3)plant materials as carbon sources. Overall high delta N-15 values (delta N-15 values > 5.5 parts per thousand) of the cultivated mushrooms enabled a differentiation to wild growing saprophytes. Furthermore, the broad range of delta N-15 values (Delta=7 parts per thousand) 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 delta N-15 values (parts per thousand) 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.

Automated summary

The study analyzed the stable carbon and nitrogen isotope signatures of cultivated button mushrooms to determine their growth medium. Results showed that the investigated mushrooms from the German market primarily used C(3) plant materials as carbon sources, with over 50% of the samples related to high shares of animal manures in the compost mixture. The minimal variation in stable nitrogen isotope values over subsequent years indicated a high level of standardization in individual cultivation processes.