Growing the fungus Pythium irregulare in a crude glycerol and a yeast extract can lead to production of an EPA-rich biomass that could be used as an omega-3 fortified food, according to researchers from Virginia Polytechnic Institute and State University and the USDA's Agricultural Research Service.
The findings are published online ahead of print in the Journal of Agricultural and Food Chemistry.
Time-line and costs
Lead researcher Zhiyou Wen told NutraIngredients that commercialisation depends on many other factors including process optimization, the EPA yield/productivity, the price of EPA in the existing market, and the FDA approval of this product.
However, Dr Wen estimated that EPA-fortified food from biodiesel-derived crude glycerol could be available in “at least three to four years, if everything works well”.
Commenting on the potential cost of the EPA from this source, Dr Wen added: “The economics depended on many factors which we don't know yet, so it is almost impossible for me to estimate the cost at this moment.”
The researchers grew P. irregulare in a medium containing crude glycerol and yeast extract. Under such conditions the EPA yield and daily productivity reached 90 mg/L and 14.9 mg/L, respectively, they said.
When they tried adding pure flaxseed oil and soybean oils, an enhancement of both the biomass and EPA production was observed, they said, due to a absorption of the oil by the fungal cells, and elongation of the shorter chain fatty acids, such as linoleic acid and alpha-linolenic acid, into EPA and other longer chain fatty acids.
The constitution of the glycerol-derived fungal biomass was found to be 40 per cent carbohydrate, 15 per cent lipid, and 36 per cent protein.
The researchers also report that, in addition to EPA, “the fungal biomass was also rich in the essential amino acids lysine, arginine, and leucine, relative to many common feedstuffs”.
Minerals, such as calcium, copper, iron, magnesium, manganese, phosphorus, potassium, and zinc, were also detected in the biomass, while no heavy metals, like as mercury and lead, were detected, they added.
“The above results indicate the great potential of producing EPA from biodiesel-derived crude glycerol by fungal fermentation. However, compared with microalgae (e.g., diatom) for EPA production, particularly at heterotrophic conditions, the biomass, EPA content, and EPA yield obtained from this work were still low,” said the researchers.
“To fully realize the potential benefits of fungal EPA production from crude glycerol, future work is needed to thoroughly optimize culture conditions and develop high cell density culture techniques,” they concluded.
Dr Wen confirmed that the research is ongoing, but admitted that there hasn’t been “too much progress so far”.
Source: Journal of Agricultural and Food Chemistry Published online ahead of print, ASAP Article, 6 March 2009, doi: 10.1021/jf803922w“Use of Biodiesel-Derived Crude Glycerol for Producing Eicosapentaenoic Acid (EPA) by the Fungus Pythium irregulare” Authors: S.K. Athalye, R.A. Garcia, Z. Wen