The fear and the dread of you shall be upon all the beasts of the earth and upon all the birds of the sky – everything with which the earth is astir – and upon all the fish of the sea; they are given into your hand. Genesis 9:2
Fish is very healthful and should be an integral part of our diets, but the time when the oceans can provide all the fish we need is ending due to overharvesting and pollution.
Instead, the world is headed towards aquaculture – fish grown in artificial ponds. By 2030, it is estimated that over 60% of fish for food will come from aquaculture rather than wild catches. Keeping fish healthy and reproducing is essential to meet the growing demand.
Prof. Itzhak Mizrahi of Ben-Gurion University of the Negev (BGU) in Beersheba – together with colleagues from Israel’s Agricultural Research Organization and the Hebrew University of Jerusalem – have discovered how the core microbiome of fish functions.
The microbiomes of fish are complex communities made up of protists (diverse collections of microscopic and one-celled organisms, highly organized with a nucleus and specialized cellular machinery called organelles); yeasts; viruses; and bacteria. These communities inhabit the skin, gills and gastrointestinal tract of the fish.
The team learned about the unique microbiome by identifying the generalist and specialist microbial gut communities and how they coexist across a number of fish species. Microbial communities of bacteria are little understood, but there is a growing consensus that they play important roles in their host’s lives.
“Our main research interest is to understand the ecological and evolutionary forces that shape microbial communities in nature and specifically, in gut environments. Understanding these forces enables us to predict and modulate the composition of the microbiome towards optimized functionality,” explained Mizrahi, who recently published the team’s findings in the prestigious journal Nature Microbiology.
The microbiome’s microbes are consistently present in a particular habitat. If the conditions in that habitat are highly variable, core microbes may also be considered to be ecological generalists. But little is known about whether metabolic competition and microbial interactions influence the ability of some microbes to persist in the core microbiome while others cannot.
The team discovered that there are some microbial communities that exist across fish species and across various parts of the gut and that these species are more genetically variable when compared to other members of the microbiome; this feature makes it possible for them to cope with the variety of hosts and gut conditions. Surprisingly, these microbes tend to help each other instead of mostly competing against each other.
“Once we understand how these microbial communities work in the fish’s gut, we can engineer them to optimize the fish’s survivability and growth,” said Mizrahi, who is a member of BGU’s department of life sciences in the Faculty of Natural Sciences and a member of the National Institute for Biotechnology in the Negev (NIBN).
Since domesticated fish will represent much of the world’s supply in another decade, such optimization is critical to ensure continued supply. Mizrahi’s group has just been awarded an European Research Council Consolidator Grant and a DIP-German Israeli Project Cooperation Grant to continue his groundbreaking research into the microbiome.
NIBN is a unique research institute located within BGU with a mission to conduct multi-disciplinary, applied and innovative research guided by a biotechnological vision and to lead the commercialization of novel technologies developed by NIBN researchers. Its research fields focus on cancer, infectious diseases, autoimmune and metabolic diseases, human genetic disorders, neurodegenerative diseases, and applied biotechnology.