In 1991 he moved to HZI (formerly GBF) where he headed the Research Group Microbial Interactions and Processes, which specialized on the analysis of the functioning and the optimization of microbial communities for the in-situ biodegradation. Currently, he is working on human associated microbial communities and their interactions with pathogens. Due to the change in focus, the Resaerch Group changed its name to „Microbial Interactions and Processes“.