Microbial Communication - Talking Microbes?
Microorganisms are generally considered to be pathogens. In fact, most microbes are beneficial or even vital to humans and to nature. It has only recently been realized that microorganisms are able to communicate. They start multiplying in a habitat only when they receive chemical messages from related cells, indicating that ambient conditions are suitable. They live in close associations with plants, animals or human beings and exchange signals with the cells of their hosts so that their hosts recognize them as friends, rather than enemies. However, there are also harmful microbes that fake these chemical signatures in order to infiltrate and infect organisms. Before starting to infect an organism, these germs recognize suitable host cells by means of chemical signals. “Microbial Communication” in natural habitats has manifold facets and, therefore, is often extremely complex.
Depending on the environmental conditions and on interacting organisms, microorganisms respond with the production of a multitude of low molecular weight compounds mediating chemical signaling processes. One of the more striking discoveries from genome sequencing efforts is the demonstration that, based on current knowledge of biosynthesis pathways and their organization, most soil bacteria and filamentous fungi possess the genetic capacity to produce a multitude of different small molecules. Induction of such compounds likely depends on biotic or abiotic interactions.
Most microbial small molecules have evolved to be global regulators within microbial communities in the environment; their roles are of ecological and evolutionary significance. Small molecules play important roles in microbial communities such as soils, the rhizosphere, the gastrointestinal tract and other stable populations, or in pathosystems. Communication includes the function of signaling molecules as attractants or repellents. Interaction between individuals of one fungal species in mating interaction is regulated by pheromones, and the parasitic or mutually beneficial symbioses also depend on a constant exchange of signals.
Until now little was known about the complex molecular interactions based on signaling in microbial interactions. This is true in particular for fungi, which constitute one major research topic in Jena. It is essential to unravel completely the communication processes at the molecular level. The signaling mechanisms have to be investigated in order to understand formation and stability of microbial consortia and their interactive networks.
New strategies based on knowledge gained of microbial communication will be useful, for example, for identification and production of pharmacologically active substances. Applications of this knowledge allow for cooperation with industry partners. Such applications can be observed in nature conservancy where the elimination of contaminants is the result of microbe-environment interactions, in agriculture where plant growth promotion and increased plant stress tolerance is mediated through root symbiotic interactions or in medicine by stimulating the defense against pathogenic microorganisms.
Examples of products that have come out of such collaborations are:
- A better understanding of the global element cycles by understanding the underlying microbial processes
- Targeted utilization of the extraordinary capacities of the microbial metabolism (e. g. microbiological bioremediation of soils contaminated with heavy metals)
- Predicting the effects of human impacts on natural systems
- Knowledge of interactions between microorganisms and higher organisms with agricultural relevance (plants and animals)
- New drugs to fight infectious diseases
- Insights into the processes involved in microbial infections
- Innovative diagnostic tools
- New technology to identify microbial signals