ИСТИНА

Fungi are an integral component of terrestrial and aquatic ecosystems (Kanzler et al., 2007). Mycelial forms (filamentous fungi) predominate among the aquatic fungi. Aquatic fungi can have a substantial environmental impact by entering into a symbiotic relationship with hydrobionts (Abdel-Lateff et al. 2002), acting as infectious agents for hydrobionts (Pivkin, Kuznetsova, and Sova 2006), and also causing many human health problems (Moh. Al-gabr et al. 2013). In terrestrial and aquatic ecosystems, fungi can serve as indicators of the ecological state and dynamics of organic matter. Pollutions and other destructive environmental processes lead to structural and functional deformation of fungal communities (Terekhova 2007; Ivanova and Marfenina 2015; Terekhova et al. 2017). However, fungi identification and quantification in aquatic ecosystems using traditional microbiological methods is complicated. The searching of new non-contact rapid methods for characterisation and classification of fungi is very actual due to the significant impact of soil and aquatic fungi on biosphere functions and human health. We focused on examination of fluorescence proxies able to distinguish chromophoric matter occurring in different fungi cultures. Spectroscopic studies were performed on five strains of filamentous fungi with different pigmentation: Trichoderma harzianum, Fusarium solani, Alternaria alternatа, Cladosporium cladosporioides, and Aspergillus terreus. Typical fluorescence emission of fungal particles (spores and pieces of mycelium) in water under UV excitation consisted of two overlapping bands: protein fluorescence with maximum located at 350 nm, and a broad band at 400–500 nm originating from NAD(P)H or melanins. We discovered a good correlation between protein fluorescence and concentration of fungal spores in water. Under excitation at 310 nm, the fluorescence of investigated strains differed in wavelength of emission maximum: for A. alternata and C. cladosporioides the maximum position was blue-shifted (400–410 nm) compared to that for T. harzianum (440–450 nm). The spectra of five fungal species cultivated as planktonic (in liquid medium) or surface-associated forms (suspended in water after growing on agar-containing medium) turned out to be different. However, we were able to distinguish different fungal species using excitation-dependent fluorescence emission. This may help to indicate fungal contamination of aquatic environments.