The Environmental Biotechnology Group at the University of Tübingen is seeking three excellent PhD candidates to join our international and dynamic team of engineers, microbiologists, and biotechnologists. Our group pioneers biotechnological platforms that connect microbial processes to future industrial applications while uncovering fundamental principles of microbial interactions, resilience, and adaptation. We are expanding our bioreactor cultivation program and opening three PhD positions that will shape new cultivation strategies and applications. At the heart of each position lies the ambition to better understand how microbes interact, adapt, and perform in controlled environments. You will use advanced cultivation techniques to address questions related to microbial physiology and community dynamics. At the same time, there is room to develop and refine the experimental platforms themselves, including opportunities to integrate automation, real-time data analysis, and intelligent control strategies to advance how we cultivate microbes. If you are primarily driven by curiosity about microbial life or equally motivated to develop the tools that allow us to study it, one of these positions will offer a stimulating and supportive environment to grow scientifically and creatively. We offer three PhD positions, each exploring a distinct research direction: PhD position 1: Connected communities. You will expand our newly developed cultivation platform in which multiple bioreactors exchange media but not biomass. This system allows us to investigate and control microbial interactions across physically separated yet metabolically connected communities. PhD position 2: Teach anaerobes to survive a breath of air. You will push oxygen-sensitive microbes to their limits, uncover how they adapt to transient oxygen exposure, and engineer bioreactors that transform this physiological constraint into a process advantage. PhD position 3: New biopolymers for a sustainable world. You will develop an integrated bioprocess for producing PHA-cellulose biopolymers in open-culture fermentations, combining anaerobic cellulose conversion with aerobic PHA production to create innovative and sustainable materials. All PhD candidates will work closely together within our bioreactor team and collaborate with international research partners at the University of Santiago de Compostela (Spain), Delft University of Technology (The Netherlands), and the University of Queensland (Australia). The projects provide hands-on experience with advanced bioreactor systems, microbial ecology, enrichment and selection strategies, and sustainable process engineering. We seek motivated and curious students with a Master’s degree in Environmental Biotechnology, Biochemical Engineering, or a related field, who are excited about microbial systems. You should enjoy both experimental and conceptual work, be eager to learn, and value teamwork. Experience with bioreactors, analytical instruments, and microbial cultivation is a plus. Good communication skills and fluency in English are essential, as it is the working language of our group You will join a friendly, international, and highly collaborative team working on projects that combine fundamental science with real-world impact. We offer three PhD positions (TV-L E13, 65%) for three years, including health insurance and full university benefits. The preferred start date is June 1, 2026. The University of Tübingen is committed to equal opportunity and diversity; we particularly encourage applications from underrepresented groups in science.