Biological transformations of hydrocarbons without oxygen: from the molecular to the global scale
Hydrocarbons are an important fossil energy source and serve as widely used raw material for the chemical industry. On the other side they comprise many toxic compounds which are of environmental concern due to their persistence and relatively high water solubility. The biological formation, transformation and degradation of hydrocarbons play an important role in the global carbon cycle. In the absence of oxygen, the quantitatively important anaerobic metabolism of hydrocarbons comprises many so far unknown enzymatic processes. In particular, the initial reactions involved in activation of chemically inert C-H-bonds appear to follow unprecedented biochemical principles.
The objective of the interdisciplinary priority programme is to study the anoxic transformations of hydrocarbons in a greater scientific environment. Researchers in the field of ecophysiology, microbiology, biogeochemistry, biochemistry, chemistry and structural biology/biophysics are involved. The following major questions are being studied:
- What novel enzymatic principles are involved in the anaerobic transformation of hydrocarbons?
- Which role do these biological transformations indeed play in nature?
- Which ecological and geochemical parameters have an impact on hydrocarbon metabolizing organisms/processes in nature?
The studies are carried out with hydrocarbon model compounds with characteristic structural features such as chemically inert C-H and C-C bonds. The compounds studied comprise saturated and non-saturated alkanes, isoprenoids and aromatic hydrocarbons. Next to the initial activation reactions, further typical reactions in the metabolism of hydrocarbons will be studied such as benzene ring dearomatization or the cleavage of cyclohexane rings. In addition hydrocarbon analogues carrying chemically inert C-H bonds are studied. The pure description of microbial communities or environmental sites is not the purpose of this research programme. Furthermore, the well understood ecology of methane formation is excluded from this research programme. The main objective is to obtain novel insights into the anoxic metabolic processes involved in the formation/degradation of hydrocarbons and their in situ regulation.
The following topics are part of the research programme:
-biochemical identification of novel or poorly understood enzymatic reactions including the isolation of enzymes their structural and regulatory characterization
-the elucidation of reactions mechanism by studying analogous chemical reactions
-the quantitative determination of the impact of geochemical and biological parameters on the transformations of hydrocarbons
-the identification and isolation of novel organisms with the capacity to anaerobically degrade methane, alkanes, aromatic hydrocarbons or isoprenoids