The casing layer in the culture of Agaricus bisporus, the cultivated mushroom

The casing layer is an essential component of the system employed in the culture of Agaricus bisporus. The literature appropriate to the casing layer is fully reviewed, including aspects relating to fructification and morphogenesis in A.bisporus, together with an appraisal of the various media employed, their properties and functions, and the commercial significance of the casing layer. Equipment is described for use in experiments in mushroom culture, based on a scaled-down version of normal growing technique, allowing the analysis of both weights and number of fruitbodies forming, which was useful in assessing the effects of different casing treatments. The basic steps in the production of fruitbodies in A.bisporus.are described, including a photographic study of the colonisation of casing and fructification. Various alterations to the physical structure of peat/chalk casing mixtures were found to have an effect on fructification; those causing an opening-out of the casing structure tended to give better yields, especially in the early stages of production. It was shown that, in order to obtain greater yield through casing amendment, fructification must be stimulated, giving increased numbers of fruitbodies, disproportionate to their total weight and consequently of lower mean weight. A synthetic casing medium based on the light glass-like mineral, perlite, was developed. The best formula obtained was -.1 part perlite: 1 part montmorillonite clay (by weight): 3 parts 0.01% glucose solution. Perlite/montmorillonite casing could be improved by adding compost colonised by mycelium of A.bisporus, or adding a peat-chalk casing extract. Perlite was also found to be suitable for admixture with the standard casing medium and a mixture of equal parts by volume performed as well as the peat/chalk casing normally used.

Studies on the composition and nutritional value of the cultivated mushroom, agaricus bisporus (Lange) Sing

The effects of various cultural conditions on the composition and nutritional quality of Agaricus bisporus (Lange) Sing. were investigated. Variation in composition was found between different classes of sample. Sampling techniques were standardised to allow for major variations in the different developmental stages and culture ages. Fruitbodies were found to be of low calorific value but contained protein of high digestibility and quality, containing all the essential amino acids required by man. Quantitative estimates of the sulphur-containing amino acids indicated that fruitbodies were deficient in methionine and cysteine. The extent of water application and the supplementation of conventional substrates with various nitrogen-containing substances, influenced yield and composition, establishing the importance of these two factors in the physiology of fruitbodies and cultural management. Storage conditions influenced composition, high temperatures being deleterious to the nutritional value of fruitbodies. Submerged culture techniques were used to investigate the effects of various nutrients on growth and composition of mushroom mycelium, with special reference to the sulphur-containing amino acids. Yield and composition were greatly affected by the carbon:nitrogen ratio of the medium and by the nitrogen source. Significant increases in mycelial methionine content were observed on the addition of inorganic sulphate, the methionine derivative N-acetyl-L-methionine, and L-methionine. A greater increase in methionine content was obtained when the biomass of a thermophilic bacterium isolated from compost was used as a nitrogen source.

Medicinal nitro compounds

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