Microbial Interactions and Processes

Microorganisms in the environment are living in complex and interacting communities. Also the surfaces of the human body are inhabited by microorganisms, where the bacterial cell number significantly exceeds that of the human cells. These communities have co-evolved with the human host and are important for human health. They can, however, also be a reservoir for pathogenic microorganisms.

Prof Dr Dietmar Pieper


Prof Dr Dietmar Pieper
Head of Research Group

Our Research

Even though an immense amount of knowledge is available on single microorganisms, our understanding of the functioning of complex communities of millions of cells and of hundreds or thousands of species is limited. Such complex communities also inhabit the human body, where they support human health. If the complex balance between microbial communities and human host becomes disrupted, this may result in disease. Moreover, the communities inhabiting humans may also be a reservoir for pathogenic microoganisms.

However, microorganisms inhabiting the human body are living in complex communities, where only the minority of community members can be isolated and analyzed in traditional pure culture studies. In order to understand microbial communities, it is necessary to apply methods that do not rely on culturing and rather derive from the field of molecular microbial ecology research than from classical infection research.

Central to our research is a close collaboration with clinicians and the analysis of samples of clinical importance. We use a cost-effective pipeline for high-throughput analysis of microbial communities in human samples to identify relationships between microbial community composition and disease and/or environmental factors. We are involved in clinical trials to identify microbial risk factors or to rationally manipulate microbial communities. Central research subjects are the analysis and quantification of functions of special importance for human health and the characterization of the activity of microbial or "pathogenic" communities in vivo.

Example nose and skin:

Roughly 20-30 % of humans permanently carry Staphylococcus aureus in their nose. Even though this colonisation of the nares is asymptomatic, it was shown to be the major source and risk factor for invasive infections by Staphylococcus aureus, an increasingly multi-resistant pathogen causing a large spectrum of infectious diseases with high morbidity and mortality. We are currently analyzing the interactions between S. aureus and other members of the nasal community and characterize the in vivo activity of S. aureus, to provide insights for future intervention strategies for the control of health care- and community-associated infections due to S. aureus. 

The analysis of in vivo activities is also used by us to understand and therefore be capable to combat infections such as necrotizing fasciitis, which are caused by single pathogens, for example S. aureus oder Streptococcus pyogenes, but also by interacting pathogenic microbial communities. These analyses also allow to decipher the interactions between "pathogenic community" and host. 

Example gut:

The microbial community structure of our intestine is determined by genetic and environmental factors such as nutrition. Applying detailed analyses on community structures, we aim to understand if changes in microbiota composition relate with disease and how they affect disease progression.

Bacterial activities in the human body are essential for the host, yet some can promote host damage. For instance, formation of short-chain fatty acids is essential for maintaining host health by providing energy to the intestinal epithelium and  modulating the immune system, whereas other metabolic products are associated with disease such as trimethylamine that is believed to promote atherosclerosis. The detailed investigation of such bacterial key functions will provide crucial knowledge on the interplay between nutrition, intestinal microbiota and disease and assist the development of precision medicine to promote host health.