The Power of Model Systems
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Host gut motility is a significant contributing factor controlling strain competition and population dynamics of the gut microbiota. A recent study at University of Oregon, US, used light sheet fluorescence microscopy (LSFM) to directly image bacterial populations in the gut of larval zebrafish.
The factors that shape the composition of our resident gut microbiota are not well understood; identifying them is an important step toward developing treatments for diseases associated with microbial imbalances.
Other research typically focuses on indirect measurements of intestinal communities, such as phylogenetic profiling of faecal material using high-throughput sequencing of 16S rRNA genes. These approaches don’t typically produce spatial and temporal information on gut microbial interaction. So the team used larval zebrafish as a model vertebrate host with LSFM to image bacterial populations in situ and interrogate the growth dynamics of two representative species (Aeromonas and Vibrio) which exhibit a competitive interaction within the zebrafish gut.
The team observed that interplay between each population and the peristaltic movement of the gut environment produced distinct spatio-temporal patterns. As a consequence, the Vibrio population dominated while Aeromonas experienced sudden drops in abundance that fit well with a stochastic mathematical model. Further proof was provided using ret1 mutant hosts, which lack a functional enteric nervous system and exhibit minimal gut motility, where the Aeromonas population was measurably more stable than in the wild type.
The team is now exploring additional factors in the host/microbe interactions to yield further and deeper insights into the dynamics of host-associated microbiota.
Raghuveer Parthasarathy, Associate Professor at the Department of Physics, University of Oregon, commented “By directly watching bacteria in the gut, we can see how microbial communities are shaped by the physical forces of the intestinal environment. For macroscopic ecosystems of animals and plants, we're used to realizing that the physical environment matters, but for the gut microbiota so far, these sorts of dynamics have been out of sight and out of mind."