2 MICROBES: MASTERS OF THE GLOBAL ELEMENT CYCLES

Prokaryotes, i.e., classical Bacteria and Archaea, are excellent catalysts which enable not only simple exergonic redox reactions to proceed but can also couple exergonic with endergonic reactions, e.g., in biosynthesis. As true for all biochemical processes, microbial transformations can be highly specific and can direct reactions specifically towards single types of highly defined products, e.g., to the production of only one type of enantiomeric product. Microbes can combine endergonic activations at the beginning of a reaction chain with exergonic steps at a later stage in a transformation sequence. With the enormous breadth of microbially catalyzed reactions, nearly every energetically feasible reaction can be catalyzed by microbial activities, and numerous reactions that were considered in the past as purely chemical processes have been found later to depend on microbial activities. Through microbial growth, the catalytically active biomass can dynamically adapt to the needs of specific transformation processes, depending on the amount of energy derived in the respective reactions. Given the broad diversity of their reaction capacities, microbes hold great promise for applications in degradative and biosynthetic activities, also in the future.