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We focused on the production of docosahexaenoic acid (DHA)-containing microbial lipids by Aurantiochytriumsp. using of defatted soybean (DS) as a nitrogen source. Defatted soybean is a plant biomass that could provide a sustainable supply at a low cost. Results showed that Aurantiochytriumsp. could not directly assimilate the DS as a nitrogen source but could grow well in a medium containing DS fermented with rice malt. When cultivated in a fermented DS (FDS) medium, Aurantiochytriumsp. showed vigorous growth with the addition of sufficient sulfate and chloride ions as inorganic nutrients without seawater salt. A novel isolated Aurantiochytriumsp. 6-2 showed 15.8 ± 3.4 g/L DHA productivity (in 54.8 ± 12.1 g/L total fatty acid production) in 1 L of the FDS medium. Therefore, DHA produced by Aurantiochytriumsp. using FDS enables a stable and sustainable DHA supply and could be an alternative source of natural DHA derived from fish oil.Graphical AbstractFor the development of novel fish feed, docosahexaenoic acid (DHA) produced by a novel isolated strain Aurantiochytriumsp. 6-2 was applied as an alternative source of DHA by using defatted soybean treated with koji.

ABSTRACTCyclooxygenases are responsible for the production of prostaglandin H2(PGH2) from arachidonic acid. PGH2can be converted into some bioactive prostaglandins, including prostaglandin F2α(PGF2α), a potent chemical messenger used as a biological regulator in the fields of obstetrics and gynecology. The chemical messenger PGF2αhas been industrially produced by chemical synthesis. To develop a biotechnological process, in which PGF2αcan be produced by a microorganism, we transformed an oleaginous fungus, Mortierella alpina1S-4, rich in triacylglycerol consisting of arachidonic acid using a cyclooxygenase gene from a red alga, Gracilaria vermiculophylla. PGF2αwas accumulated not only in the mycelia of the transformants but also in the extracellular medium. After 12 days of cultivation approximately 860 ng/g and 6421 µg/L of PGF2αwere accumulated in mycelia and the extracellular medium, respectively. The results could facilitate the development of novel fermentative methods for the production of prostanoids using an oleaginous fungus.

An isomer of the conjugated linoleic acid (CLA) produced from linoleic acid by Lactobacillus plantarumwas identified as cis-9,trans-11-octadecadienoic acid by proton nuclear magnetic resonance spectroscopy. Together with earlier results, we concluded that the bacterium produces two CLA isomers, cis-9,trans-11- and trans-9,trans-11-octadecadienoic acid from linoleic acid. The addition of L-serine, glucose, AgNO3, or NaCl to the reaction mixture reduced production of the latter.

Ricinoleic acid (12-hydroxy-cis-9-octadecaenoic acid) was an effective substrate for conjugated linoleic acid (CLA) production by washed cells of Lactobacillus plantarumAKU 1009a. The CLA produced was a mixture of cis-9,trans-11- and trans-9,trans-11-octadecadienoic acids. Addition of α-linolenic acid to the culture medium increased the CLA productivity of the washed cells. In the presence of lipase, castor oil, in which the main fatty acid component is ricinoleic acid, also was a substrate for CLA.