The main areas of interest and research are: • syntrophic communities of anaerobic bacteria and archaea • sulfate-reducing bacteria and their interaction with methanogenic communities • anaerobic bacteria that respire with organic and inorganic chlorine compounds Scientific synopsis Prof. Alfons Stams started his international scientific career as PhD student at the University of Groningen, the Netherlands, where he studied the ecophysiology of sulfate-reducing bacteria. He discovered that amino acids in sediments are not degraded by sulfate-reducing bacteria alone, but by obligate syntrophic communities of amino acid-degrading bacteria and sulfate-reducing bacteria. This was a crucial discovery for our understanding of how the anaerobic food chain functions. He realized that syntrophy is a very important and relevant process in anaerobic environments, and he decided to continue his scientific career in that area of research. This became possible when Prof. Alexander Zehnder offered him a postdoc position at Wageningen University, where he started to study syntrophic conversions in methanogenic environments. Over the years Alfons Stams discovered a large number of new syntrophic interactions, even during studies where syntrophy was not expected to play a role. He performs forefront research on one of the most important phenomena in the microbial world. Alfons Stams has 30 years research experience with anaerobic microbial communities, especially those that are key players in environmental biotechnological processes. Besides studying topics that are scientifically challenging, he finds it very important that his research is relevant for application. While keeping a focus on anaerobic conversions, he developed as scientist. He went through all disciplines that are essential to understand the microbiology of anaerobic communities; physiology, molecular ecology and biochemistry, and since some years including genomics approaches. His main areas of interest and research are: • syntrophic communities of anaerobic bacteria and archaea • sulfate-reducing bacteria and their interaction with methanogenic communities • anaerobic bacteria that respire with organic and inorganic chlorine compounds The main achievements of the past decade that impacted or will impact the scientific community concern: •Into-depth insight of the physiology and bioenergetics of obligate syntrophic methanogenic communities that degrade fatty acids. A large set of functionally different hydrogenases and hydrogenases were found to be present in bacteria that grow in obligate syntrophy with methanogens. The large set of terminal reductases is essential to provide syntrophic communities flexibility to thermodynamic constraints of the conversion that they catalyze, •Discovery of novel syntrophic conversions such as syntrophic growth on amino acids and one-carbon substrates (methanol, formate, CO). From the energetic and biochemical viewpoint syntrophic growth with formate was most remarkable, as it concerns a simple hydrolysis of formate to hydrogen and carbon dioxide, •Isolation and description of 10 novel genera and 19 novel species of anaerobic microorganisms. Most of the novel species turned out to catalyze key functions in the process that was studied, •The first successful enrichment of anaerobic methane-oxidizing communities of archaea and bacteria. This is an important achievement as anaerobic methane oxidation coupled to sulfate reduction is known for more than 30 years, but successful enrichment was never described, •The description of anaerobic bacteria that produce oxygen from chlorate and employ aerobic pathways in the absence oxygen, as demonstrated for degradation of benzene and decane, •The discovery of a novel perchlorate-reducing pathway in hyperthermophilic archaea, involving the sulfur cycle. As perchlorate reduction and sulfate reduction occur at contrasting redox potentials, it was very remarkable.