Antarctic fungi: a bio-source alternative to produce polyunsaturated fatty acids (PUFAs).

The Antarctic ecosystems are a combination of conditions, including extremely low values of temperature and humidity. Nonetheless, some organisms, such as fungi, can adapt to these extreme conditions. The environmental temperature is one of the parameters thoroughly affecting the structure and composition of fungal membrane lipids. The psychrophilic fungi generally increase the disorder within macromolecules to maintain membrane fluidity at low temperatures. To do so, Antarctic fungi increase the proportion of unsaturated fatty acids that allow maintaining a semi-fluid state of the membranes and survive at extremely low temperatures. This ecological feature may be of interest for the characterization of phenotypical traits of the ecological adaptation of these fungi to the extreme environmental conditions of Antarctica. Moreover, this can be of inspiration to find solutions inspired by nature for alternative sources of polyunsaturated fatty acids (PUFAs) for diets of humans and animals. We characterized three fungal strains isolated from Antarctica and set up a laboratory/small-scale production of fungal biomass with a high content of beneficial PUFAs. In detail, three fungal species previously isolated from Antarctic environmental matrices were tested and identified at the genome level. We also conducted growth experiments to determine the effects of temperature and substrate on biomass and PUFA production. The results showed that these fungi have a high percentage of PUFAs compared to saturated ones; the growth at low temperatures (10°C) increases the production of linolenic acid (C18:3) while the biomass amount (yield) depends on the composition of the growth substrate; a satisfying qualitative-quantitative production is achieved using agri-food chain waste products, such as brewing and whey waste, as a growth substrate.IMPORTANCEThe presence of polyunsaturated fatty acids (PUFAs) in the diets of humans and animals is gaining attention because PUFAs have several recognized functional properties: they modulate immune response, have anti-allergic and anti-inflammatory activity, have a cardio-protective effect, and reduce blood LDL cholesterol levels. Since few foods naturally contain high levels of PUFAs, human diets are often deficient in these fatty acids, which is why supplementation is often needed. Regarding this, it is necessary to develop efficient industrial processes capable of producing good-quality PUFAs and in quantity, even using agri-food chain waste products as carbon and nitrogen sources (in our case, spent yeast from brewing and whey waste). Like microorganisms, we took into consideration Antarctic fungi because they can adapt to very low temperatures also by increasing the proportion of unsaturated fatty acids that allows maintaining a semi-fluid state of their membranes. The innovation of our study consists of a characterization of phenotypical traits on PUFA production by fungal strains from Antarctica in different cultural conditions, including the use of agri-food processing wastes. The combination of these conditions can be an inspiration for a new, alternative, and sustainable way to produce PUFAs with extreme microorganisms.