Overview

Halogenated hydrocarbons (organohalides) can be detected at many sites. They may be of natural or anthropogenic origin. Especially those halogenated compounds released into the environment by human activities are often ecologically harmful, toxic, and/or carcinogenic; moreover, volatile halogenated compounds destroy the ozone layer of our planet. Frequently halogenated compounds such as tetrachloroethene (PCE) are widely recalcitrant at contaminated sites, since they are degraded or dehalogenated, respectively, only at rather low rates.

The biological dechlorination of highly chlorinated compounds, e. g. PCE, at such sites is performed by strictly anaerobic bacteria that are able to respire with halogenated hydrocarbons (organohalide respiration) in the absence of oxygen. In the course of this respiration, the halogenated compounds are reductively dehalogenated. This process is coupled to the synthesis of ATP, meaning energy conservation.

The planned research will focus on the organohalide respiration. In the course of this research, all significant aspects of this novel type of anaerobic respiration will be investigated. These aspects comprise the physiology and biochemical catalytic mechanisms as well as the mechanisms of energy conservation, the structure and topology of the respiratory chain, and the regulation of the components involved. A prerequisite for these studies is the knowledge of the genomes of organohalide-respiring bacteria. A few genome sequences are already known and published, others will be revealed in the research projects as parts of the research unit. On the basis of these sequences, the components of the organohalide respiratory chain may be identified under appropriate experimental conditions and may later be characterized in more detail.

The planned studies will contribute on the one hand to the understanding of the organohalide respiration and its role in the global halogen cycle and, on the other hand, to the application of this process for the bioremediation of sites contaminated with halogenated compounds.