Tropical fish adapt to cold temperatures in coordination with their microbiome

November 20, 2018

Scientists have discovered that tropical fish can control their gut microbes to better survive extremes of temperature, a study in eLife reveals.

The results add further weight to the concept of a 'hologenome' - where a living organism is not viewed as an individual animal or plant but as a community: the host organism plus all of the microbes that live within it. Within this concept, host-microbe interactions play an important role in the fitness of the host, while microbiome composition may in turn be affected by host fitness.

"One of the most significant environmental pressures that affects the fitness of a host organism is temperature," explains lead author Fotini Kokou, Postdoctoral Research Fellow at Ben Gurion University of the Negev, Israel. "In this study we wanted to test whether acclimatisation to temperature is facilitated by changes in the host's microbiome."

The team used the tropical fish, blue tilapia, which are normally highly sensitive to the cold, but as part of a selective breeding scheme are being bred with increased cold tolerance at the Agricultural Research Organization in Israel. This allowed comparison of the microbiomes between the cold-sensitive and cold-resistant fish, at different extremes of temperature.

They first exposed 84 fish with inherited low or high tolerance to the cold to temperatures of 24°C or 12°C and analysed their gut microbiomes using genetic sequencing. They found a dramatic reduction in microbial diversity in both groups of fish exposed to the cold. This suggests that low-temperature conditions are very selective and limit the variety of microbes that can survive in the fish.

Next, they looked at how the inherited temperature tolerance in the fish influences microbiome diversity. When they compared the gut microbes from the cold-sensitive and cold-resistant fish, they found that the innate temperature tolerance of the fish had a pronounced effect on the diversity of its gut microbes to begin with. They also found that the gut microbes in the fish responded differently when exposed to the cold. This led them to conclude that the host genetics has a strong effect on shaping the microbiome.

The researchers next turned attention to the meaning of these changes to the microbiome. Analysis of the types of microbes that were abundant after cold exposure showed that the host tends to select microbes that are themselves tolerant to the cold. Indeed, the microbiomes of the cold-resistant fish appear to have a core group of microbes that are maintained, whereas the core group of microbes living in the cold-sensitive fish was altered dramatically after exposure to low temperatures.

Finally, the team sought to understand the characteristics of the fish gut microbes that flourished in response to cold. They found that during cold exposure, the microbes tended to switch off processes that expend energy (metabolism) and turned on cell processes that were related to a stress-and-defense response. This mirrored the response seen in the genes of the fish themselves, suggesting that exposure to cold triggers a concerted energy-saving, stress-induced adaptive response that involves both the fish host and its microbiome.

"Our study shows that the genetic background of the tilapia fish and its tolerance to temperature-induced stress determines the response of the gut microbiome to temperature," concludes senior author Itzhak Mizrahi, Associate Professor of Microbial Ecogenomics at Ben Gurion University of the Negev. "Our findings are consistent with the emerging hologenome concept, which suggests that microbes and their hosts work together in a survival of the fittest as part of the natural-selection process."

The paper 'Host genetic selection for cold tolerance shapes microbiome composition and modulates its response to temperature' can be freely accessed online at Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.

Media contact

Emily Packer, Senior Press Officer
01223 855373

About eLife

eLife aims to help scientists accelerate discovery by operating a platform for research communication that encourages and recognises the most responsible behaviours in science. We publish important research in all areas of the life and biomedical sciences, including Microbiology and Infectious Disease, which is selected and evaluated by working scientists and made freely available online without delay. eLife also invests in innovation through open-source tool development to accelerate research communication and discovery. Our work is guided by the communities we serve. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, the Wellcome Trust and the Knut and Alice Wallenberg Foundation. Learn more at

To read the latest Microbiology and Infectious Disease research published in eLife, visit


Related Microbes Articles from Brightsurf:

A new look at deep-sea microbes
Microbes found deeper in the ocean are believed to have slow population turnover rates and low amounts of available energy.

Microbes might manage your cholesterol
Researchers discover a link between human blood cholesterol levels and a gene in the microbiome that could one day help people manage their cholesterol through diet, probiotics, or entirely new types of treatment.

Can your gut microbes tell you how old you really are?
Harvard longevity researchers in collaboration with Insilico Medicine develop the first AI-powered microbiomic aging clock

What can be learned from the microbes on a turtle's shell?
Research published in the journal Microbiology has found that a unique type of algae, usually only seen on the shells of turtles, affects the surrounding microbial communities.

Life, liberty -- and access to microbes?
Poverty increases the risk for numerous diseases by limiting people's access to healthy food, environments and stress-free conditions.

Rye is healthy, thanks to an interplay of microbes
Eating rye comes with a variety of health benefits. A new study from the University of Eastern Finland now shows that both lactic acid bacteria and gut bacteria contribute to the health benefits of rye.

Gut microbes may affect the course of ALS
Researchers isolated a molecule that may be under-produced in the guts of patients.

Gut microbes associated with temperament traits in children
Scientists in the FinnBrain research project of the University of Turku discovered that the gut microbes of a 2.5-month-old infant are associated with the temperament traits manifested at six months of age.

Gut microbes eat our medication
Researchers have discovered one of the first concrete examples of how the microbiome can interfere with a drug's intended path through the body.

Microbes can grow on nitric oxide
Nitric oxide (NO) is a central molecule of the global nitrogen cycle.

Read More: Microbes News and Microbes Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to