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Research & Infrastructure

Medicaco sative root nodules pictures
Photo: B. Frage, D. Kapp
Medicago sativa root nodules (left), root nodule section (middle), and electron microscopy of Sinorhizobium meliloti bacteroids (left).

Our team-oriented research aims at understanding and applying the fundamental design principles of bacterial gene regulation and genome architecture. Our major bacterial model organisms belong to the Alphaproteobacteria ‒ one of the most abundant classes of bacteria on Earth.  Alphaproteobacteria are remarkably diverse and many members of this class of bacteria are closely linked to complex life forms. Mitochondria, the powerhouse of all eukaryotic cells, evolved from members of this class of bacteria and many intracellular pathogens and symbionts of animals, humans, plants, and other eukaryotes are Alphaproteobacteria.

Examples are rhizobia which induce and invade specialized plant organs ‒ root nodules ‒ and fix di-nitrogen in an endosymbiotic bacteroid state within the plant cell. Symbiotic nitrogen fixation by the rhizobium-legume plant symbiosis is an important pillar of sustainable agriculture. It enables reducing the use of nitrogen fertilizers produced by consumption of fossil fuel and thereby contributes to mitigating the greenhouse effect and ground-water pollution from excess nitrogen fertilizers.


Synthetic microbiology, microbial genetics, bacterial cell biology, regulatory networks, microbe-host interactions, polysaccharides, genomics and transcriptomics, bacterial genome editing and engineering, laboratory automation

Selected Publications

Krol E, Stuckenschneider L, Kästle Silva JM, Graumann PL, Becker A. (2021) Stable inheritance of Sinorhizobium meliloti cell growth polarity requires an FtsN-like protein and an amidase. Nat Commun. 12(1):545.

Schäper S, Steinchen W, Krol E, Altegoer F, Skotnicka D, Søgaard-Andersen L, Bange G, Becker A (2017) AraC-like transcriptional activator CuxR binds c‑di‑GMP by a PilZ-like mechanism to regulate extracellular polysaccharide production. Proc Natl Acad Sci USA 114: E4822-E4831

Döhlemann J, Wagner M, Happel C, Carrillo M, Sobetzko P, Erb TJ, Thanbichler M, Becker A (2017) A family of single copy repABC-type shuttle vectors stably maintained in the alpha-proteobacterium Sinorhizobium meliloti. ACS Synth Biol 6: 968-984

Salas MA, Lozano MJ, Lopez JL, Draghi W, Serrania J, Torres Tejerizo GA, Albicoro FJ, Nilsson JF, Pistorio M, del Papa MF, Parisi G, Becker A, Lagares A (2017) Specificity traits consistent with legume-rhizobia coevolution displayed by Sinorhizobium meliloti rhizosphere colonization. Environ Microbiol 19: 3423-3438.

Krol E, Becker A (2014) Rhizobial homologs of long-chain fatty acid transporter FadL facilitate perception of long chain N-acyl-homoserine lactone signals. Proc Natl Acad Sci USA 111: 10702-10707.