Volume 17 Part 1 Article 27: Volatile 8-Carbon Compounds and Bacterial Populations Influence Initiation of Mushroom (Agaricus bisporus) Primordia

Volume 17 Part 1 Article 27
Year 2008
Title: Volatile 8-Carbon Compounds and Bacterial Populations Influence Initiation of Mushroom (Agaricus bisporus) Primordia
Authors: A. Dobrovin-Pennington, R. Noble and P.J. Hobbs


Experiments were conducted with Agaricus bisporus cultures in axenic and non-axenic microcosms and in non-axenic trays, in which different pseudomonads and volatile organic compounds (VOCs) were introduced and/or monitored. VOCs produced by A. bisporus mycelium were predominantly 8-carbon compounds, some of which could inhibit the formation of primordia, with 1-octen-3-ol being most inhibitory. The results also showed that a VOC produced by the rye grain substrate on which A. bisporus was grown, 2-ethyl- 1-hexanol, could inhibit primordial formation. 2-ethyl-1-hexanol and 1-octen-3-ol were metabolised by the casing microbiota and adsorbed by activated charcoal casing, with both modes of removal enabling primordia formation. Removal of VOCs by ventilation also enabled the initiation of primordia to occur on peat-based casing under axenic conditions. The presence of 2-ethyl-1-hexanol and 1-octen-3-ol in the microcosms resulted in higher total bacterial and pseudomonad populations in the casing. Inoculation of casing with several Pseudomonas isolates resulted in large increases in the pseudomonad population, but none were able stimulate primordia formation in axenic casing to the same extent as a naturally occurring microbiota in non-axenic casing, or enhance the initiation of primordia in non-axenic casing. This indicates that either a mixed pseudomonad or bacterial population is more stimulatory to primordial formation than individual pseudomonads. The results indicate that a function of the casing and its microbiota is to remove VOCs inhibitory to primordia initiation of A. bisporus. The requirement for ventilation for stimulating primordia initiation of A. bisporus, which has previously been attributed to a reduction in carbon dioxide concentration, may be at least partly due to a reduction in the concentration of inhibitory VOCs.

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