Host adaptation in gut Firmicutes is associated with sporulation loss and altered transmission cycle

The coevolution between humans and these symbiotic, anaerobic bacteria requires that individual bacterial taxa faithfully and efficiently transmit and colonize since the inability to do such results in the extinction of the native microbiota [5–8].
Browne et al. 2021 Genome Biology 22: 204

Intestinal bacteria must settle above a certain abundance to achieve a sufficient rate of excretion for further transmission and must survive in the environment long enough to encounter a susceptible host [7].
Browne et al. 2021 Genome Biology 22: 204

Once ingested, intestinal bacteria must pass through the gastrointestinal tract, compete with the hu…