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.

The paper presents data that testify in favor of the participation of the cytochrome P450 system in the light emission of higher fungi. Extracts from mycelia of different species of luminous basidiomycetes containing fungal luminescent systems that provide luminescence in vitro were obtained. Applied conditions for the isolation of luminescent systems (sonication, centrifugation at 40000g) indicate the presence of membrane structures in the extracts, in particular, microsomes formed as a result of ultrasonic disintegration of the endoplasmic reticulum (ER). Differential spectral analysis of the extracts revealed the presence of two absorption peaks at 410 nm and 450 nm, which indicates the presence of cytochromes b5 and P450. The luminescence of the extracts is stimulated by reduced pyridine nucleotides, however, the addition of NADPH causes a higher level of luminescence compared with NADH. The addition of hydrogen peroxide significantly (from several times to 1-2 orders of magnitude) increases the luminescence intensity of extracts activated by NAD(P)H. The addition of fluconazole significantly inhibits the light emission of extracts. The data obtained indicates that the cytochrome P450 system associated with ER membranes may participate in the mechanism of light emission of higher fungi with the involvement in the process of electron transport enzyme systems: NADPH-dependent reductase of cytochrome P450 - cytochrome P450 and NADH-dependent reductase of cytochrome b5 - cytochrome b5 - cytochrome P450. In this case, cytochrome P450 may hydroxylate hispidin (precursor of the luminescent reaction substrate) to form luciferin and catalyze its oxidation in the presence of ROS with light emission.

A functionalized composite γ-Al2O3 nanofibers / nanodiamond / Cu2+ with improved sensor properties for the detection of phenols in an aqueous medium was obtained by chemical modification with copper ions of a new composite material based on alumina nanofibers and nanodiamonds. The chemical modification of the composite made it possible to increase its catalytic activity more than twice in the co-oxidation of phenols with 4-aminoantipyrine in the presence of H2O2. The obtained effect enabled to reduce the threshold of the minimum detectable concentration of analytes by half when they were tested using a functionalized composite. What was demonstrated by the example of the detection of phenol and 4-chlorophenol. It was shown that the obtained composite provides a linear response in a wide range of concentrations of phenol (0.25–100 μM) and 4-chlorophenol (0.5–25 μM). It is found that the adsorbed Cu2+ ions are firmly bound to composite surface, are not desorbed, and are not inactivated by co-oxidation reagents during repeated use of the composite. The applicability of a functionalized composite as a reusable sensor was shown in model experiments in the course of sequential multiple testing of phenol in aqueous samples. Comparative studies of the kinetics and isotherms of adsorption of Cu2+ ions on a composite material and an alumina matrix, and estimation their sorption capacity were also carried out in the work.