Stable isotope characterization of fungal water and inorganic carbon assimilation signals and ecosystem fluxes

Stanislav JABINSKI

Doctoral thesis

Enzymatic combustion and pyrolysis products to reveal cycling of recalcitrant organic matter in soils and sediments

Abstract:

Fungi are a group of major decomposers in soils and therefore play a key role in the biogeochemical cycles in environmental systems. To get a better understanding of their metabolic role, we extended a dual stable isotope probing assay which applies labeled bicarbonate as inorganic C and heavy water (2H2O). The advantages of this approach are that both are overly abundant in the environment and therefore do not disturb or add nutrients into natural systems. Only little information could be found in the literature regarding the potential of inorganic carbon assimilation by fungi and no information could be found for the hydrogen water assimilation. Therefore, this PhD was aimed to investigate the isotopic signatures of a diverse phylogenetic range of saprotrophic fungi to explore the variations in the fungi when grown under different substrate classes before applying the obtained knowledge to incubations of natural systems. To fully apply this assay potential, we investigated under laboratory conditions the potential of assimilation of inorganic C and the hydrogen water assimilation into the membrane lipid biomarkers of fungi to distinguish differences in metabolic modes specifically targeting the difference in growth on labile vs more complex C sources.

Abstract:

Fungi are a group of major decomposers in soils and therefore play a key role in the biogeochemical cycles in environmental systems. To get a better understanding of their metabolic role, we extended a dual stable isotope probing assay which applies labeled bicarbonate as inorganic C and heavy water (2H2O). The advantages of this approach are that both are overly abundant in the environment and therefore do not disturb or add nutrients into natural systems. Only little information could be found in the literature regarding the potential of inorganic carbon assimilation by fungi and no information could be found for the hydrogen water assimilation. Therefore, this PhD was aimed to investigate the isotopic signatures of a diverse phylogenetic range of saprotrophic fungi to explore the variations in the fungi when grown under different substrate classes before applying the obtained knowledge to incubations of natural systems. To fully apply this assay potential, we investigated under laboratory conditions the potential of assimilation of inorganic C and the hydrogen water assimilation into the membrane lipid biomarkers of fungi to distinguish differences in metabolic modes specifically targeting the difference in growth on labile vs more complex C sources.

Keywords

Lipid-SIP, microbial fatty acids, Soil incubation, microbial production, hydrogen isotopes, heterotrophic CO2 fixation

Language used: English

Date on which the thesis was submitted / produced: 23. 10. 2024

Thesis defence

• Supervisor: Travis Blake Meador, Ph.D.

UNIVERSITY OF SOUTH BOHEMIA IN ČESKÉ BUDĚJOVICE

Faculty of Science

Doctoral programme / field:
Biology / Ecosystem Biology