Day-night rhythm of the microbiomeIt has been earlier discovered that the bobtail squid, found predominantly in Hawaii, generates light due to its symbiosis with a luminescent bacterium, V. Fischerii. This bacteria provides necessary protection of the squid from it predators, as the bacteria allows the squid to hide by imitating moonlight reflecting of the ocean surface at night, making the squid less visible underwater. This form of protection is only required at night, and coincidingly the squid only generates this pattern of light at night. Research has shown that the luminescent bacteria is only active at night, as only then the required nutrients are available for it to be able to generate the fluorescence. This nutrient is in turn produced by the squid. The scientific name for this nutrient is the protein MIF, which is a regulator of the immune system. This protein is produced in higher quantities at night. This together shows the presence of a diurnal effect of the bacteria residing in the squid.
The MIF protein found in the squid, has recently also been discovered in the epithelial cells of the mammalian gut, and is theorized to have a similar day-night rhythmic functionality in the gut microbiome. As such, this discovery can be utilized to further research rhythmicity in the gut microbiome, and its role in the human immune system and ecosystem.