TY - JOUR TI - Gut bacterial aggregates as living gels AU - Schlomann, Brandon H AU - Parthasarathy, Raghuveer A2 - Wood, Kevin B A2 - Garrett, Wendy S A2 - Ludington, William B A2 - Iyer-Biswas, Srividya VL - 10 PY - 2021 DA - 2021/09/07 SP - e71105 C1 - eLife 2021;10:e71105 DO - 10.7554/eLife.71105 UR - https://doi.org/10.7554/eLife.71105 AB - The spatial organization of gut microbiota influences both microbial abundances and host-microbe interactions, but the underlying rules relating bacterial dynamics to large-scale structure remain unclear. To this end, we studied experimentally and theoretically the formation of three-dimensional bacterial clusters, a key parameter controlling susceptibility to intestinal transport and access to the epithelium. Inspired by models of structure formation in soft materials, we sought to understand how the distribution of gut bacterial cluster sizes emerges from bacterial-scale kinetics. Analyzing imaging-derived data on cluster sizes for eight different bacterial strains in the larval zebrafish gut, we find a common family of size distributions that decay approximately as power laws with exponents close to −2, becoming shallower for large clusters in a strain-dependent manner. We show that this type of distribution arises naturally from a Yule-Simons-type process in which bacteria grow within clusters and can escape from them, coupled to an aggregation process that tends to condense the system toward a single massive cluster, reminiscent of gel formation. Together, these results point to the existence of general, biophysical principles governing the spatial organization of the gut microbiome that may be useful for inferring fast-timescale dynamics that are experimentally inaccessible. KW - gut microbiota KW - zebrafish KW - aggregation KW - cluster size JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -