Many fungi make oils. Fungal oils recently became the focus of intense research in industrial microbiology.
There are two main impetuses for this research focus.
One, along with microalgae, certain fungi are the main microbial sources of PUFA (polyunsaturated fatty acids) (see tables below from 1, 2).
Traditionally fish were the main source of PUFA. Today, there are 2 main problems with fish as PUFA source. One, over-fishing is severely and precipitously depleting their numbers, and two, the issue of safety as increasingly fish concentrate heavy metals and other pollutants making additional steps necessary to remove them in the process of purifying PUFA.
These issues have driven intense recent search for alternative PUFA sources. Arachidonic acid is a primary PUFA of interest (see table below from 3) because it’s a precursor to eicosanoid hormones (prostaglandins, leukotrienes, thromboxanes), and also an important component of human milk (3).
Two, as a biodiesel/biofuel alternative to non-renewable fossil fuels. Called ‘green chemistry‘, the idea is to develop renewable microbial alternatives for fossil fuel-based products (4; see figure below).
- ~3 to 10% of the ~1600 known species of yeasts have been reported to be oleaginous (oil-producing). (5).
- From the phyla Basidiomycota and Ascomycota, Cryptococcus curvatus (6, 7), Cryptococcus laurentii (8), Cryptococcus podzolicus, Trichosporon porosum, Pichia segobiensis (9), Yarrowia lipolytica (10, 11), Candida orthopsilosis, Candida oleophila, Cryptococcus luteolus (12), Kodamaea ohmeri (13), Candida silvae, Meyerozyma caribbica, Pichia manshurica, and Rhodosporidium taiwanensis (1).
- Fatty acid composition of oleaginous yeasts is similar to that of vegetable oils (14).
- Since yeast can grow on a variety of inexpensive substrates, even agriculture and industry wastes, their efficient conversion of low-cost raw materials into lipids is driving industrial and commercial interest (1).
- Oleaginous yeasts are able to accumulate up to ~70% (dry mass) of their cellular biomass as lipid or oil (15).
- Polburee, Pirapan, et al. “Characterization of oleaginous yeasts accumulating high levels of lipid when cultivated in glycerol and their potential for lipid production from biodiesel-derived crude glycerol.” Fungal Biology (2015).
- Bellou, Stamatia, et al. “Microbial oils as food additives: Recent approaches for improving microbial oil production and its polyunsaturated fatty acid content.” Current opinion in biotechnology 37 (2016): 24-35.
- Ji, Xiao-Jun, et al. “Fungal arachidonic acid-rich oil: research, development and industrialization.” Critical reviews in biotechnology 34.3 (2014): 197-214.
- Ledesma‐Amaro, Rodrigo. “Microbial oils: A customizable feedstock through metabolic engineering.” European Journal of Lipid Science and Technology 117.2 (2015): 141-144.
- Sitepu, Irnayuli R., et al. “Oleaginous yeasts for biodiesel: Current and future trends in biology and production.” Biotechnology advances 32.7 (2014): 1336-1360.
- MEESTERS, PATRICIA AE P. “Cryptococcus curvatus CBS 570.” Yeast 12 (1996): 723-730.
- Meesters, P. A. E. P., G. N. M. Huijberts, and G. Eggink. “High-cell-density cultivation of the lipid accumulating yeast Cryptococcus curvatus using glycerol as a carbon source.” Applied microbiology and biotechnology 45.5 (1996): 575-579.
- Castanha, Rodrigo Fernandes, et al. “Optimization of lipids production by Cryptococcus laurentii 11 using cheese whey with molasses.” Brazilian Journal of Microbiology 45.2 (2014): 379-387.
- Schulze, Ines, et al. “Characterization of newly isolated oleaginous yeasts-Cryptococcus podzolicus, Trichosporon porosum and Pichia segobiensis.” AMB Express 4.1 (2014): 1-11.
- Boekhout, Teun, and Cletus P. Kurtzman. “Principles and methods used in yeast classification, and an overview of currently accepted yeast genera.” Nonconventional yeasts in biotechnology. Springer Berlin Heidelberg, 1996. 1-81.
- Liu, Hu-Hu, Xiao-Jun Ji, and He Huang. “Biotechnological applications of Yarrowia lipolytica: Past, present and future.” Biotechnology Advances (2015).
- Kanti, A., et al. “Indonesian oleaginous yeasts isolated from Piper betle and P. nigrum.” Mycosphere 4.5 (2013): 1015-1026.
- Kitcha, Suleeporn, and Benjamas Cheirsilp. “Enhancing lipid production from crude glycerol by newly isolated oleaginous yeasts: strain selection, process optimization, and fed-batch strategy.” Bioenergy Research 6.1 (2013): 300-310.
- Liu, Yanbin, Chong Mei John Koh, and Lianghui Ji. “Bioconversion of crude glycerol to glycolipids in Ustilago maydis.” Bioresource technology 102.4 (2011): 3927-3933.
- Probst, Kyle V., et al. “Oleaginous yeast: a value-added platform for renewable oils.” Critical reviews in biotechnology (2015): 1-14.