Dr. Guy Schleyer

Eavesdropping on marine microbes

Guy Schleyer is a marine microbiologist and chemical ecologist, fascinated by the ways microbes communicate. “I work at the interface between these two fields”, he says. “Because, to understand how microorganisms in the marine environment communicate, it is essential to integrate both chemical and biological approaches.”

Ecological interest

The various compounds that are produced by microorganisms in the marine environment have attracted the attention of scientist for a long time. “Most of the time, this is due to their potential pharmaceutical potential, such as antimicrobial activity”, Schleyer says. However, his interest is of a more fundamental nature. “I am interested in these compounds from an ecological perspective – their involvement in mediating interactions between microorganisms.”

The base of the food web

Many interactions exist in the marine microbial world, which forms the basis of the marine food web. Bacteria can support the growth of algae, for example, but can also prey on them. Viruses can infect and kill algal populations, which can, in turn, try to defend themselves. Such interactions can determine the course of important large-scale geochemical processes in the ocean and, consequently, even regulate our climate. “This means that, if you understand the chemical signals between various microorganisms, you get a better picture of what is happening at the base of the marine food web”, Schleyer says. “It comes down to ‘eavesdropping’ on the talk between these microorganisms and deciphering it. A bacterium can sense specific metabolites produced by algae, saying: there are algae around! The bacterium can then kill these algae to obtain their nutrients, for example.”

Sophisticated analyses

This eavesdropping on the chemical communication between marine microorganisms requires sophisticated analytical instrumentation. “Recent technological advancements in mass spectrometry have made it possible to profile a microorganism’s metabolome and lipidome. This means we get a detailed description of all metabolites and lipids it produces.” Despite this progress, however, a major challenge remains, Schleyer stresses. “Understanding the precise functions of these metabolites within the microorganism’s life cycle and their ecological roles in the complex marine environment is the next level. To tackle this, we begin by studying simplified experimental systems in the lab, which consist of only a few interacting microorganisms. Compounds that play functional roles in these interactions are then used as means to detect and study microbial interactions in more complex environmental system.”