Microbes are widely used to break down plant biomass into sugars, which can be used as sustainable building blocks for novel biocompounds. Getting the right microbial community for this process is still a matter of trial and error. New insights by University of Groningen microbial ecologist Dr Diego Javier Jiménez and colleagues could make a rational design possible. They argue this point in an opinion paper published in the journal Trends in Microbiology on 22 June.