ARA belongs to the n-6 polyunsaturated fatty acid family, which is a vital essential fatty acid for human health. It plays a crucial role in the development of brain function and the retina. Normally, the human body can synthesize the necessary amount of ARA from linoleic acid. However, in infants, the elderly, and certain patients with diabetes, the enzyme system responsible for converting linoleic acid into ARA may be incomplete or inhibited, resulting in inadequate synthesis and, consequently, ARA deficiency. Therefore, dietary supplementation of ARA becomes particularly important for these populations.
ARA is abundant in animal tissues, but historically, commercial sources like pig liver and deep-sea fish have yielded low quantities of ARA, typically around 0.2% by weight. Additionally, the quality was inconsistent, costs were high, and these sources struggled to meet market demands. As a result, researchers have redirected their attention towards microbial sources of ARA.Currently, the primary method of obtaining ARA is through biological fermentation technology, which has opened up a new avenue for various populations to supplement and enhance their ARA intake.
Among microorganisms, certain microalgae (including red algae and cyanobacteria), bacteria, and yeast have the ability to produce ARA, albeit in relatively low yields, thereby limiting their practicality for large-scale production. Nonetheless, studies conducted both domestically and internationally have identified several species within the genus Mortierella, notably Mortierella alpina, Mortierella elongata, Mortierella isabellina, Mortierella lamanensis, and Mortierella ultima, as exhibiting exceptionally high yields of ARA, positioning them as promising candidates for industrial-scale production.
The production of ARA through fermentation boasts several advantages:
(1) The microbial growth rate is rapid, and the yield of ARA is high;
(2) The growth and metabolism of microorganisms are readily influenced by external conditions, allowing for the promotion of ARA synthesis through modifications to these conditions;
(3) The fermentation process is relatively straightforward and not constrained by limitations in raw materials;
(4) The extraction of ARA from microorganisms is more straight forward than from animal sources.
