Research and development has led to levels of the long-chain polyunsaturated fatty acid (LC-PUFA) of EPA (eicosapentaenoic acid) in rapeseed (Brassica napus) of around 15 per cent, said Dr Thorsten Zonk from BASF Plant Science at the final Lipgene conference in Dublin on 4th December 2008. Fatty acid levels in fish range from 10 to 20 per cent.
“We still don’t know how stable this oil is,” said Dr Zonk. “But this could be a sustainable and cheap source of long-chain polyunsaturated fatty acids (LC-PUFA).”
BASF is an industrial partner the EU-sponsored Lipgene project, an EU Sixth Framework Programme Integrated Project. The German company has been collaborating with Rothamsted Research and the University of York in the UK.
Other companies are active in this area, and Monsanto has been working on a stearidonic acid (SDA)-containing soybean oil. The company told NutraIngredients.com that it expected the oil to be commercially available after the turn of the decade (see related article).
Dr Zonk said the rapeseed oil is “still quite far away from a market introduction”.
The potential of plants
Fears about dwindling fish stocks, coupled with the putative risk of pollutants from oily fish, have pushed some in academia and industry to investigate the extraction of omega-3 from alternative sources.
Indeed, docosahexaenoic acid (DHA) extracted from non-GM microalgae is already on the market, as is plant-source alpha-linolenic acid (ALA), a shorter chain omega-3 that has relatively low conversion rates in humans to EPA (about 10 per cent), and subsequently DHA.
The principle of the GM approach is to add genes that convert shorter chain omega-3 and omega-6 fatty acids, found naturally in the plants, into more bioavailable longer chain fatty acids.
The added genes come from a range of other organisms, but are mostly sourced from microorganisms such as fungi.
According to Prof Napier’s article in Current Opinion in Biotechnology (2007, Vol. 18, pp. 142-147) to transform ALA to EPA, genes are required that encode for the desaturation of ALA (by the enzyme, delta6-desaturase) to form stearidonic acid (SDA). An enzyme called delta-6 elongase then elongates the SDA from an 18-carbon chain to a 20-carbon chain, and further desaturation, this time by the delta5-desaturase enzyme, results in the production of EPA.
An alternative route via a delta-8 pathway is also possible.
For DHA production, two more genes are needed to code for enzymes that further elongate and desaturate, making DHA a significantly bigger challenge for scientists.
The enzymes which act to desaturate and elongate the fatty acids also work on the omega-6 fatty acids found in plants, with linoleic acid converted to gamma-linolenic acid (GLA) and then to arachinodonic acid (ARA).
Dr Zonk reported that ARA production is even higher than for EPA, but would not specify further. ARA is important for infant formula, added Prof Napier.
Challenges remain
The ultimate success of these oils relies heavily on acceptance by consumers of the genetically modified tag that comes along with the source.
Johnathan Napier, a professor of Crop Performance and Improvement (CPI) from Rothamsted Research and member of the Lipgene project, told NutraIngredients.com in Dublin: “It will be very interesting to see how it all gets played out. The markets in the US are very different from markets in the EU.”
Stephen Daniells’ attendance at the Lipgene conference was funded by University College Dublin, the coordinating institute of the network.