A stimulator of light emission of the fungus was found in an aqueous extract from mycelium of the luminous basidiomycete Neonothopanus nambi after its treatment with β-glucosidase. The addition of the extract to the luminous mycelium increases the level of light emission from several times to 1.5 orders of magnitude or more. The luminescence stimulator is a low-molecular-weight thermostable compound: it is detected in the permeate after filtering the extract through a 10-kDa cutoff membrane and it retains the stimulating effect after heat treatment at 100°C for 5 min. In the absorption spectrum of the aqueous sample of the stimulator, two main peaks are observed in the shortwave region (205 and 260 nm) and a shoulder in the range of 350-370 nm can be seen. The luminescence stimulator exhibits blue fluorescence with an emission maximum at 440 nm when excited at 360 nm. It was established that the luminescence-stimulating component is not a substrate (or its precursor) of the luminescent system of the N. nambi fungus.
Keywords: Neonothopanus nambi; bioluminescence; fluorescence; light emission stimulator; luminescent mycelium.
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