Lemnagene extols duckweed virtues for biomanufacturing

Duckweed or Lemna, belonging to the Lemnaceae​ family, is commonly encountered in freshwater and takes the form of small, free-floating plants that will be instantly recognisable to those with garden ponds. It is a fast-growing plant, as many gardeners who have to scoop it out of their ponds almost daily will testify, and this is one reason why it is so valuable in protein production.

"Lemna has a doubling time of two days and is easy to propagate on water containing salts and with access to light and carbon dioxide,"​ noted Freyssinet, pointing out that this is much cheaper than the complex media used to grow mammalian cell cultures, for example. It can be beneficial to secrete proteins into an aqueous medium in some cases.

In addition, the company can achieve expression levels of 1-3 per cent and as Lemna has a high protein content - 45 per cent of its dry weight - the yields are good. Lemna can also be cultivated all year under controlled pond environments - a more flexible option to plant systems that use whole plants.

Moreover, Lemna can be used to produce stable cell lines incorporating the gene coding for the desired protein in as little as three to six months, allowing biomass production to take place very rapidly. This rapidity rivals that of mammalian cell cultures, and is much faster than rival plant-based biomanufacturing platforms, said Freyssinet.

Duckweed has safety advantages as well, he pointed out. Like other plants, it overcomes the risk of viral contamination that is present with mammalian systems, but also has benefits over other plant systems.

For example, it does not produce pollen, reducing the risk that the genetic modification could spread into the environment, which is a concern with crop-based biomanufacturing using plants such as tobacco or alfalfa.

Interestingly, the recombinant proteins produced in the plants can thus be either extracted and purified or the plant containing the protein can be used directly, dry or fresh, without the extraction/purification of the active ingredient.

This opens up other possibilities for Lemnagene in the nutraceuticals industry, said Freyssinet, although he noted that at present the company has its sights firmly fixed on the pharmaceutical sector, not least because of the difficult situation in Europe for companies looking at the development of GM foods.

That said, one pharmaceutical application of using a whole dried plant could be in the production of dried, orally active vaccines. Feeding studies of the first candidates are due to start next year, he told In-Pharmatechnologist.com​.

Lemnagene has just produced its first transgenic Lemna containing genes of interest to industrial partners, and has already expressed several proteins. One project has seen Lemna being used as to produce an enzyme, and the company has already shown that this is feasible and that the enzyme retains its expected activities. However, more work needs to be done on scale-up, noted Freyssinet.

Looking forward, Freyssinet said the company is funded for the next few months thanks in large part to a €400,000 grant from the French government. But it will need to convert some of its pilot partnerships into full-blown collaborations, or tap into the venture capital markets, thereafter.