Fig. 4
From: Host adaptation in gut Firmicutes is associated with sporulation loss and altered transmission cycle
Host adaptation is associated with an altered transmission cycle in gut Firmicutes. Former-Spore-Formers (FSF) are more host-adapted compared to Spore-Forming (SF) bacteria as measured by their reduced genome size and genomic redundancy and their more specialist metabolic capabilities. This greater level of host-adaptation corresponds to an ability to colonize to higher abundance levels which promote onward direct transmission to hosts in close proximity. By contrast, SF are less host-adapted and colonize to lower abundance levels. SF transmission cycle relies on the production of resilient spores that promote environmental persistence; thus, they are capable of colonizing a greater proportion of hosts and have a greater prevalence in human populations. Figure adapted from [7]