"Our laboratory studies the molecular interactions of microbes and microbial communities in complex environments like biofilms"

Molecular interactions of microbes in biofilms

Microbial biofilms are environments where microbes express complex patterns of metabolic and genetic interactions. Consumption of and competition for nutrients as well as signaling and other interactions between biofilm microbes create a highly heterogeneous and dynamically changing environment that varies on a micrometer scale. Microbes respond to such dynamic changes by coordinated physiological but also by genetic and genomic adaptations, thus giving rise to a tissue-like, functional compartmentalization.

Our research on molecular microbial interactions is focused on

1. Genetic/metabolic control of cell attachment, biofilm maturation, and detachment

2. Genetic/metabolic control of microbe-mineral and microbe-microbe interactions

3. Evolution of single species and co-evolution of microbial communities in biofilms

4. Molecular basis controlling stability, resilience and invasibility of biofilms

The studies are conducted with three model microbes Shewanella oneidensis, Vibrio cholerae, and Caulobacter crescentus as well as with natural microbial isolates using biochemical, genetic, and genomic tools.

Novel metabolism and metabolic engineering of microbes.

Anaerobic microbes have evolved unusual enzymes and biochemical pathways for degradation of environmental pollutants, including chlorinated aliphatic hydrocarbons, such as trichloroethene, dichloroethene, and vinyl chloride (VC). Our laboratory has discovered the first anaerobic enzyme to degrade vinyl chloride, a known human carcinogen, to the harmless ethene. The reductive VC dehalogenase as well as the encoding gene is studied on a molecular and biochemical level. We also investigate the in vitro evolution of dehalogenases by directed evolution to obtain novel and better enzymes for bioremediation.

The metabolic engineering focus is on engineering cyanobacteria to produce molecular hydrogen. Molecular hydrogen is the most promising future energy carrier as it combusts to water without the formation of green house gases or other pollutants. In order to develop a technology for sustainable, environmentally compatible production of hydrogen on a large scale, we explore the biochemical and genetic machineries of oxygenic photosynthesis in cyanobacteria. In oxygenic photosynthesis, solar energy is used to convert water to 'bound' hydrogen and oxygen. The molecular engineering of cyanobacteria, specifically of Synechocystis, Anabena and related species, involves construction of novel metabolic pathways to release 'bound' hydrogen as molecular hydrogen gas, directed evolution of enzyme, and re-engineering of microbial control mechanisms.