Enhancement of arachidonic acid production by Mortierella alpina 1S‐4

Abstract

The effect of mineral addition on arachidonic acid (AA) production by Mortierella alpina 1S-4 was evaluated. At first, the addition of minerals such as sodium, potassium, calcium, and magnesium was examined in flask cultures, and then the addition of phosphorus with the optimal amounts of the minerals was investigated in a 10-L jar-fermenter. As a result, 1.5% soy flour medium with the addition of 0.3% KH 2 PO 4 , 0.1% Na 2 SO 4 , 0.05% CaCl 2 ·2H 2 O, and 0.05% MgCl 2 ·6H 2 O was found to enhance the AA yield 1.7-fold over that without mineral addition. When 1% yeast extract with the above mineral mixture was used, the AA yield was enhanced 1.35-fold over that without minerals. We also verified that an increase in the polar lipid content occurred in the case of only KH 2 PO 4 addition, and that the above-mentioned increase in the AA yield was due to the minerals themselves, not a pH buffer effect. JAOCS 75, 1501-1505 (1998).Arachidonic acid (5,8,11,14-cis-eicosatetraenoic acid, AA) acts as a precursor for prostaglandins and leukotrienes, which have various regulatory effects and physiological activities. It is the most abundant C 20 polyunsaturated fatty acid (PUFA) in humans, and plays important roles in infant nutrition (1,2). There are various sources of AA, including fungi (3), animal liver, tuna (4), and egg yolk. Fungal oil seems to be the most advantageous among these sources in the aspects of production cost and product handling, because of its high AA content and the structure of its triacylglycerol (TG).In the previous paper (3), we reported the isolation of Mortierella alpina 1S-4 as a potent producer of AA and the fundamental culture conditions. In order to obtain a higher production yield, further optimization of the culture conditions is essential. Phosphorus, potassium, sulfur, calcium, sodium, and magnesium are major inorganic constituents of fungi (5); these minerals should be supplied sufficiently, and optimization of the additional concentration is important. Therefore, we attempted to enhance the AA productivity by optimization of the amounts of these minerals. MATERIALS AND METHODSMicroorganism and culture conditions. Mortierella alpina 1S-4 (3) was used throughout this study. A stock culture was stored on a Czapek medium (0.2% NaNO 3 , 0.1% K 2 HPO 4 , 0.05% MgSO 4 ·7H 2 O, 0.05% KCl, 0.001% FeSO 4 ·7H 2 O, 3% sucrose, and 2% agar) slant in a test tube at 5°C.For the flask culture study, 2 mL medium containing 4% glucose and 1.5% soy flour, with or without the addition of minerals, pH 6.3, was prepared in a 10-mL Erlenmeyer flask, and then 0.1 mL of a spore suspension obtained from the stock culture was inoculated, followed by incubation for 7 d at 28°C at a reciprocal speed of 150 rpm.For the jar-fermenter study, the inoculum was prepared in a 500-mL flask containing 100 mL medium including 1.8% glucose and 1% yeast extract, with shaking for 3 d at 28°C, and the main culture was carried out in a 10-L jar-fermenter (Able Corp., Tokyo, Japan) with a working volume of 5 L medium at 28°C, an i...

Single cell oil production by Mortierella alpina

“…The main product of the strain, AA, is synthesized through the n-6 pathway, which involves 12 and 6 desaturases, elongase (EL2), and 5 desaturase. Depending on the conditions, the total amount of AA varies between 3 and 20 g/L (30-70% of the total cellular fatty acids), with 70-90% of the AA produced being present as triacylglycerols (Higashiyama et al, 1998Shimizu et al, 2003b). Although fatty acid desaturase inhibitors, such as cyclopropene fatty acids, and microbial uptake of supplemented fatty acids from cultural media were reported (Aggelis, 2003;Aggelis et al, 1997;Moreton, 1985), cultivation of the Mortierella strain under certain conditions also leads to a variety of PUFAs being produced, for example: (a) lowering of the growth temperature (<20 • C) with simultaneous addition of ␣-linolenic acid (18:3n-3) to the medium results in the production of EPA (Shimizu et al, 1988(Shimizu et al, , 1989b; (b) the addition of 5 desaturase inhibitors such as sesamin (Shimizu et al, 1991a) to the growth medium causes an increase in DGLA (Shimizu et al, 1989a); (c) utilization of C15 and C17 n-alkanes by the strain yields PUFAs with odd numbers of carbons in their chains (total C17 and C19 fatty acids reached over 95% of the mycelial fatty acids (Shimizu et al, 1991c); (d) n-1 PUFAs (20:5n-1, 20:4n-1, 18:4n-1, etc.)…”

Enhancing arachidonic acid production by Mortierella alpina ME-1 using improved mycelium aging technology

“…Under the optimal aging conditions, ARA yield was increased from 10.02 g/l after 6.5 days fermentation in a 5 l scaled fermentor to 19.02 g/l after another 5.6 days aging, which was higher than the previously reported yields [25][26][27]. The relatively high ARA yield displays the potential of using the improved aging technology in developing bioprocess for commercial production of ARA.…”

Effects of Mineral Addition on Production of .GAMMA.-Linolenic Acid by Rhizopus nigricans.

“…Berkley (19) studied a medium, in which low Mg was desirable for arachidonic acid (AA) production; the effect of addition of phosphorous on AA production has been studied by some groups (20)(21)(22). K. Higashiyana et al (17) reported the effect of addition of minerals, such as Na, K, Ca and Mg on arachidonic acid (AA) production by Mortierella alpina IS-4. He observed that 1.5% soy flour medium with the addition of 0.3% KH 2 PO 4 , 0.1% Na 2 SO 4 , 0.05% CaCl 2 .…”