Glowing guts?- The intestinal microbiome of Atlantic cod

The fish intestinal microbiome contains a complex and specialised gut bacterial community which is important for multiple functions, including metabolism, growth and development. Riiser et al., (2018) identified a gap in the research comparing healthy wild fish from the same species living in different habitats. Atlantic cod are an economically and ecologically important species in the North Atlantic Ocean. Their ability to exploit a wide range of ecological niches may influence the composition of its intestinal microbiome; this makes it an interesting model species to look at.

In this study, they used metagenomic shotgun sequencing to explore the intestinal microbiome of 19 adult Atlantic cod individuals from two study sites. Overall no significant differences in microbiome composition were found in species from both study sites. However, results identified two abundant species, Photobacterium kishitanii and Photobacterium iliopiscarium in individuals from both study sites. P kishitanii can generate bioluminescence which may suggest that fish intestines form a niche for bioluminescent bacteria.

It is still unclear of the functional role of both Photobacterium in the Atlantic cod intestines; further research needs to be done to explore this as well as the reasoning behind their high abundance.

Riiser, E., Haverkamp, T., Varadharajan, S., Borgan, Ø., Jakobsen, K., Jentoft, S. and Star, B. (2019). Switching on the light: using metagenomic shotgun sequencing to characterize the intestinal microbiome of Atlantic cod. Environmental Microbiology, 21(7), pp.2576-2594.