P.A.G. ter Horst (Peter)

Methane is a potent greenhouse gas, with a global warming potential about 28 times higher than CO₂ over a 100-year timescale. Net methane emissions reflect the balance between microbial methane production (methanogenesis) and consumption (methanotrophy), making microorganisms key regulators of methane fluxes. Methanotrophy can proceed either aerobically, using oxygen as the terminal electron acceptor, or anaerobically via alternative electron acceptors. Although anaerobic methanotrophy, including anaerobic oxidation of methane (AOM), is widespread in sediments and aquatic systems, the organisms and metabolic strategies involved remain incompletely understood, largely because many are difficult to cultivate. My research focuses on microbial methane cycling under oxygen-limited and anaerobic conditions, with particular emphasis on methanotrophy. I use bioelectrochemical systems (BES) as controlled redox platforms to investigate anaerobic methanotrophy and to enrich or isolate previously uncultivated microorganisms by providing electrodes as alternative electron acceptors. This work is complemented by anaerobic cultivation, gas chromatography, electrochemical measurements, and genome-resolved analyses. In parallel, I investigate methanogenesis, with a specific focus on alternative electron donors such as alcohols, to better understand methanogenic energy metabolism and how methanogenesis and methanotrophy together shape net methane emissions. In addition to my research, I am involved in university teaching within the Biology curriculum at Radboud University. I am practical coordinator of the Bachelor-level course Microbial Metabolism and course coordinator of the Master-level course Introduction to Microbiology within the Biology Master’s specialisation Microbiology. The Master course focuses on academic and professional skills, including scientific presentations, feedback, planning, and internship and thesis orientation.

• Microbial interactions of anaerobic methanotrophic archaea in coastal ecosystems