Genomic phase-variation as a mechanism to control gut bacterial functions

The microbiome, a complex ecosystem of microorganisms that populate the gastrointestinal tract, the skin and other surfaces of the body, is vastly important for our health. It was shown to have an important role in the development of the immune system, digestion of food and protection from pathogens. The microbiota exists in a dynamic environment, and such are required to adapt with ever-changing conditions. Our initial results indicate that one microbial mechanism for such adaptation is dynamic and reversible alteration in their genomes that can lead to functional plasticity.

Analysing the microbiome functionality on top of their taxonomy composition opens a door to new and exciting insights on the microbiome role in affecting the host in health and disease. Genomic reversible alterations are predominantly controlled by a mechanism termed phase variation, in which the directionality of the gene orientation can be altered in a reversible manner and as a consequence, for example, promoters are switched from ‘ON’ to ‘OFF’ orientations and vice versa. Such phase variations control extracellular molecules like polysaccharides that were previously shown to communicate with the host immune system.

In this study we compared phase variation alterations of bacteria in different host conditions in order to deepen our understanding on how phase variation mechanisms affect bacterial functionalities.