A heterogeneous microbial consortium producing short-chain fatty acids from lignocellulose

Building niches for multiple microbes Microbial conversion of heterogeneous feedstocks such as lignocellulose into one or more desired products requires assembly of pathways to both break down the inputs and produce the outputs. Shahab et al. assembled a collection of microbes that occupy different spatial niches within a bioreactor and have different metabolic capabilities. In the simplest version of their setup, an aerobic fungus adeptly breaks down cellulose into short sugar chains, an oxygen-tolerant bacterium converts these to lactic acid, and an anaerobic bacterium uses the lactic acid to synthesize the short-chain fatty acid butyric acid. Additional microbes handle limitations in the intermediate stream or divert lactic acid to longer-chain fatty acids, which are potentially more valuable. The integrated production and use of lactic acid for biosynthetic reactions could ideally serve as a platform for biosynthesis using robust, heterogeneous microbial consortia. Science , this issue p. eabb1214