Invertebrates inhabiting marine ecosystems, including corals, worms and molluscs appear to be equipped with the capabilities to manufacture omega-3 fatty acids.
“Our study provides a significant paradigm shift,” according to lead study author Dr Oscar Monroig, lecturer at the Institute of Aquaculture at the University of Sterling.
“It demonstrates that corals, rotifers, molluscs, polychaetes and crustaceans, possess enzymes called ‘desaturases’ that enable them to produce omega-3.”
Dr Monroig’s research takes on a number of angles, namely the transfer of genes to invertebrates in order to produce omega-3 oils and the production of omega-3 rich biomass that can be used for example as fish meal in the farming of fish, crustaceans, molluscs, aquatic plants, algae, and other organisms.
“Under specific culture conditions, these organisms may exhibit enhanced biosynthetic capabilities to enable or increase omega-3 production,” said Dr Monroig.
“The biomass produced is a substitute for a high quality fish meal so it will contain lipids rich in omega-3 oils if the process has been successful and the activation of the pathways have been done successfully.
The discovery challenges the generally held principle that marine microbes, such as microalgae and bacteria, are responsible for virtually all primary production of omega-3.
The research gains added impetus as the omega-3 sector look to explore novel sources of omega-3 sources outside of krill and fish as a response to consumer demand and greater interest in sustainability.
“We think that growing certain invertebrates in specific conditions so that we convert something that is a waste material into a nutritious biomass will be helping to ease the pressure that were putting on omega-3 sources such as krill,” Dr Monroig added.
Dr Monroig added the interest invariably stems from the health benefits associated with omega-3 oil supplementation, regularly prescribed for prevalent cardiovascular and inflammatory diseases in humans.
Along with colleagues from the Universities of St Andrews and Porto as well as the Spanish National Research Council amongst others, Dr Monroig identified the existence of key enzymes such as methyl-end desaturases in a small number of invertebrate animals.
These enzymes, which previously were found in photosynthetic marine microalgae and bacteria, formed 121 methyl-end desaturase sequences from 80 species.
As Dr David Ferrier, of the Scottish Oceans Institute at the University of St Andrews explains, the horizontal gene transfer process may explain their unusual widespread distribution.
“It was very surprising to us to see just how widespread these genes were, particularly in animals that are so common and abundant in the sea,” he said.
“It is also intriguing that these genes seem to be jumping between very different organisms, such as from plants or fungi into an insect and a spring-tail, by a process of horizontal gene transfer.
“This has been a controversial idea that genes can move around in this way, but our data looks rather convincing that these genes have done this in at least some of these species."
The new research is not only likely to impact the scientific community, but also the general public and various industries involved in the production of supplements.
“Invertebrate oils are different to fish oils,” said Dr Monroig, who also revealed that he was in contact with a Norwegian company regarding the production of omega-3 rich oil fish meal.
“Depending on the species, they are generally richer in EPA and poorer in DHA. This is a characteristic of invertebrates’ fatty acid profile compared to fish oil.
“The omega-3 oil’s quality is good. We also think that the likelihood of heavy metal and bioxin pollutants accumulating in the oils produced from invertebrates will be minimal.“
Omega-3 models ‘need extensive revision’
The study concluded that models estimating global production of omega-3 long-chain PUFA, which are largely constructed on the assumption that single-cell microorganisms are the sole primary producers, “need extensive revision,”
“Omega-3 long-chain PUFA production by metazoans will undoubtedly be significant due to the abundance that the animals that are now known to have methyl-end desaturases have in global ecosystems,” the study added.
The Global Organisation of EPA and DHA Omega-3s (GOED) director of compliance and scientific outreach, Dr Gerard Bannenberg said the study, “significantly expands our understanding of the range of multicellular animals that can desaturate polyunsaturated fatty acids at the omega-3 position”.
“The nematode Caenorhabditis elegans omega-3 fatty acid desaturase fat-1 has since long been known to be able to do this, and the transgenic mouse expressing the fat-1 gene is an important experimental animal model that has been instrumental in demonstrating the role of endogenous omega-3 long-chain polyunsaturated fatty acid (LCPUFA) in the regulation of inflammatory and metabolic processes.
“The study shows new natural sources of omega-3 fatty acids, significantly beyond our previous comprehension, and suggests that novel avenues for the directed biosynthesis and sustainable production of eicosapentaenoic acid and docosahexaenoic acid (EPA and DHA) can be developed.”
Source: Science Advances
Published online ahead of print: DOI: 10.1126/sciadv.aar6849
“Genes for de novo biosynthesis of omega-3 polyunsaturated fatty acids are widespread in animals.”
Authors: Naoki Kabeya, Miguel Fonseca, David Ferrier, Juan Navarro, Line Bay, David Francis, Douglas Tocher, L. Filipe C. Castro, and Óscar Monroig.