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Secondary metabolites and antimicrobial effects of neotropical members of the genus Hermatomyces
Ježková, Tereza ; Koukol, Ondřej (advisor) ; Žabka, Martin (referee)
Species of the genus Hermatomyces (Pleosporales) saprotrophs on wood and litter in the tropics. Since the secondary metabolites of this genus have not been investigated so far, this thesis focuses on them. In this thesis, the antifungal properties of the genus Hermatomyces were verified by pairing experiments on agar plates and by testing the minimum inhibitory concentrations of extracts obtained from fungal biomass. The extract of one selected strain, H. reticulatus CCF 5893, was separated by preparative HPLC. The selected biologically active fractions were purified and the chemical structure of the separated compounds was determined by nuclear magnetic resonance analysis and X-ray crystallography. Two compounds were found in this species: palmarumycins C2 and C12, which have antifungal properties. Furthermore, a total of 25 Hermatomyces strains were compared in terms of secondary metabolite production (by testing their minimum inhibitory concentrations and comparing HRMS data). Unique compounds were produced by H. megasporus, which also showed the highest antimicrobial activity of all species and is therefore the most suitable species for further study of antimicrobial compounds of this genus.
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The effect of secondary metabolites (essential oils) on endophytic fungi from leaves of Rhododendron tomentosum
Koudelková, Barbora ; Koukol, Ondřej (advisor) ; Žabka, Martin (referee)
Rhododendron tomentosum is an evergreen shrub with a high content of secondary metabolites, particularly essential oils with antimicrobial effects. Diversity of endophytic fungi in this species and their possible adaptation to growth in the essential oil environment is not much explored. Therefore, the first aim of this thesis was to reveal the diversity of endophytic fungi colonising leaves of R. tomentosum on seven localities in the Czech Republic and one in Estonia. I isolated and determined (using comparison of ITS1 and ITS2 rDNA with the sequences from GenBank and morphological signs) 37 species of endophytic fungi. Among them the ubiquitous species colonising the most of the plants as endophytes were dominant. The second aim of my thesis was to explore whether the essential oil from R. tomentosum influences its endophytic fungi. The hypothesis that the strains obtained from R. tomentosum would be adapted to growth in the environment of the essential oil was postulated. I supposed that they would grow better on mediums with different concentrations of these chemical compounds added, in comparison with strains of the same species obtained from different substrates. Within four of seven species tested, the strains obtained from R. tomentosum grew better, but also on the medium without the...
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The effect of secondary metabolites (essential oils) on endophytic fungi from leaves of Rhododendron tomentosum
Koudelková, Barbora ; Koukol, Ondřej (advisor) ; Žabka, Martin (referee)
Rhododendron tomentosum is an evergreen shrub with a high content of secondary metabolites, particularly essential oils with antimicrobial effects. Diversity of endophytic fungi in this species and their possible adaptation to growth in the essential oil environment is not much explored. Therefore, the first aim of this thesis was to reveal the diversity of endophytic fungi colonising leaves of R. tomentosum on seven localities in the Czech Republic and one in Estonia. I isolated and determined (using comparison of ITS1 and ITS2 rDNA with the sequences from GenBank and morphological signs) 37 species of endophytic fungi. Among them the ubiquitous species colonising the most of the plants as endophytes were dominant. The second aim of my thesis was to explore whether the essential oil from R. tomentosum influences its endophytic fungi. The hypothesis that the strains obtained from R. tomentosum would be adapted to growth in the environment of the essential oil was postulated. I supposed that they would grow better on mediums with different concentrations of these chemical compounds added, in comparison with strains of the same species obtained from different substrates. Within four of seven species tested, the strains obtained from R. tomentosum grew better, but also on the medium without the...
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