Dilution as a Solution: Targeting Microbial Populations with a Simplified Dilution Strategy.

The gut microbiota is an integral part of maintaining resistance against infection by Clostridioides (Clostridium) difficile, a pathogen of increasing concern in both health care and community settings. The recent article by J. M. Auchtung, E. C. Preisner, J. Collins, A. I. Lerma, and R. A. Britton (mSphere 5:e00387-20, 2020, https://doi.org/10.1128/mSphere.00387-20) demonstrates an innovative approach to identify microbes that inhibit C. difficile by employing a dilution scheme to test different microbial mixtures in vitro and in vivo This type of approach can advance the identification and validation of specific microbes that elicit functions of interest for many conditions involving the microbiota, of which the complexity and variability can often complicate causality.