L-ergothioneine (ERGO) is a biologically active antioxidant produced by certain fungal species and mycobacterium. The precursors to the synthesis of ERGO are the amino acids histidine, cysteine, and methionine. The objective of this study was to determine the influence of selected cultural and postharvest practices on the ERGO content present in button mushroom Agaricus bisporus. In the first experiment, the effect of supplements added to the compost was studied. Mushrooms were grown in tubs containing 22.7 kg of compost supplemented with protein-rich corn gluten at 2% and 4% of the dry weight of compost and amino acids (methionine [5 mM], cysteine [5 mM], histidine [10 mM]), and these mushrooms were compared to an untreated control. Further experiments were conducted with compost supplemented with the same amino acid(s) individually and in combination at various levels. A third experiment was conducted using various levels of histidine added to deep bags of compost. High-performance liquid chromatography was employed for quantification of ERGO, and the results indicated that protein supplement treatments had no significant effect on the amount of ERGO produced by the mushrooms, but the addition of histidine to compost in deep bags significantly increased the amount of ERGO produced. In addition, ERGO content increased significantly with each flush of the crop cycle. Further experimentation demonstrated that the extent of mycelium growth in compost significantly increased the amount of ERGO produced. The results further indicated that ERGO could be increased by up to 1.3 mg/g dry weight in later flushes by several stress factors placed on the mycelia, such as dry compost, indicating that ERGO may be a stress factor. A postharvest shelf-life study demonstrated that ERGO significantly decreased during postharvest storage for up to 6 days at 12 degrees C.
