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Omega-3s sans fish

For most of us, the phrase ?omega-3 fatty acids? conjures images of fish, whose oils are rich in those panaceas of modern nutrition. But our scaly friends don?t make omega-3s on their own. They need to eat something that ate something that ate microalgae, the unicellular plants which serve as the starting point for the ocean?s food chain and provide half of Earth?s atmospheric oxygen. In recent times, researchers have begun working on new ways to cut out the piscin

By | February 1, 2006

For most of us, the phrase ?omega-3 fatty acids? conjures images of fish, whose oils are rich in those panaceas of modern nutrition. But our scaly friends don?t make omega-3s on their own. They need to eat something that ate something that ate microalgae, the unicellular plants which serve as the starting point for the ocean?s food chain and provide half of Earth?s atmospheric oxygen.

In recent times, researchers have begun working on new ways to cut out the piscine intermediary and get the benefits of microalgal labor directly into the human diet. One approach is to grow microalgae in culture, something that Columbia, Md.-based Martek Biosciences has been doing for some time. The first infant formula that used Martek?s microalgal omega-3 fatty acids was launched in Europe in 1994, company spokesperson Beth Parker says. Their algal oils are also used in supplements and fortified foods.

These days, the company sees a growing consumer demand for omega-3s not sourced from fish, Parker says. ?While the demand for omega-3 fortified foods exists today, the demand is growing for DHA- [docosahexaenoic] fortified foods, in particular, as DHA emerges as the omega-3 for brain health,? she says.

In recent months, Australian scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO) have begun taking an even more direct approach to getting DHA into foods. In research conducted during 2005, the CSIRO team used an agrobacterial vector to transfer five genes from a microalgal strain into a crop plant and, in a world first, recently demonstrated production of DHA. They?re hoping that commercial production might be as little as eight years away. ?Our goal is to provide an alternative source of omega-3 oil to fish,? says Bruce Lee, director of the CSIRO Food Futures Flagship, which is conducting the research.

Lee describes microalgae as ?the natural omega-3 factories of the sea.? Thriving in dark, organic-rich environments where they convert carbohydrates into the beneficial oils, which are passed up through the marine food chain to fish, ?they may offer a renewable source of omega-3 oils for use in human and animal diets,? he says.

But, many different microalgal species are swimming around out there, and identifying which are most suitable for commercialization is not easy. The Aussies are in a good position to conduct this work, possessing as they do a kind of Jackson Labs for microalgae: the CSIRO Marine and Atmospheric Research laboratories, situated in Hobart, the capital of the island state of Tasmania to the south of the Australian mainland.

There, researchers nurture a collection of some 800 microalgal strains including representatives from all classes of marine microalgae, some freshwater microalgae, and the occasional marine microheterotroph. The collection is the biggest in the southern hemisphere, and the CSIRO scientists who run it provide cultures internationally to aquaculture firms, basic researchers, and more recently, biotechnology concerns. They also run courses on how to work with the organisms.

The laboratory?s researchers had been characterizing the oil production of different microalgal species for years, explains Peter Nichols, an oils chemist based in Hobart, so ?when the omega-3 stuff started taking off three or four years ago, we already had a lot of information that was relevant for choosing the most suitable strains.?

Having screened approximately 200 strains, the CSIRO researchers have focused their attention on some thraustochytrid strains that produce high levels of omega-3 oils and can be cultured to produce high biomass. The initial goal of the screening was to find strains suitable for genetically modifying land plants which, unlike microalgae, lack the enzymatic apparatus needed to convert short-chained omega-3s into the longer forms of DHA and eicosapentaenoic acid.

The Australian researchers have also recently begun a collaboration aiming to grow oil-producing microalgae in large-scale fermenters. Lee explains that a nutraceutical firm, Clover Corporation, recently approached CSIRO. Clover says it will evaluate the scale-up potential of microalgae in large-scale culture vessels.

The CSIRO-Clover collaboration hopes to achieve higher efficiency than Martek Biosciences, Lee says. In the longer term, the cultured microalgae could be used to produce oils for human consumption. Closer at hand, the collaborators see the biggest potential for use as a source of oils for aquaculture or animal feed.

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