Caffeic Acid Stimulates in Vivo Luminescence of the Mycelia of the Higher Fungi Neonothopanus Nambi and Armillaria Borealis

Abstract

In vivo experiments have shown that the addition of caffeic acid to the luminous mycelia of the higher fungi Neonothopanus nambi and Armillaria borealis stimulates a rapid and significant (by an order of magnitude or more) increase in the intensity of their light emission. It has been suggested that the observed effect of fungal luminescence activation may be mediated by the oxidation of caffeic acid by enzymes of the ligninolytic complex of basidiomycetes (in particular, by peroxidases) with the emission of visible light quanta. Comparative in vivo experiments showed that the addition of hispidin (the precursor of luciferin in the light emission reaction of higher fungi) did not affect the intensity of bioluminescence of the mycelia. At the same time, in vitro studies found that caffeic acid significantly suppressed the NADPH-hispidin-activated emission reaction of luminescent systems isolated from the mycelia of N. nambi and A. borealis. The inhibitory effect of caffeic acid is considered and discussed in the work from the standpoint of the classical biochemistry concept on enzyme inhibition by the reaction product according to the negative feedback principle. In general, the results obtained develop and supplement the understanding of the mechanisms of light emission in higher fungi and testify in favor of the fact that the generation of visible light quanta in basidiomycetes can be carried out by different biochemical pathways involving different enzymes (or enzyme systems). Clarifying the mechanism of stimulation of in vivo bioluminescence of higher fungi by caffeic acid is a priority for further research.