Arachidonic acid production byMortierella sp. S-17 influence of C/N ratio

Chang

1997

J Americ Oil Chem Soc

A fungal isolate Wuji-H4 with a dense-lobe rosette growth pattern on malt extract agar was identified as Mortierella alpina Peyronel. It was capable of producing 504 mg/L of arachidonic acid (AA) in the screening medium. Its AA content accounted for 42.4% of the total fatty acids. The AA yield was raised to 1,817 mg/L by a step-by-step approach, which uncovered that the preferred carbon source, nitrogen source, and temperature for fungal growth and lipid production were soluble starch, urea, and 24°C, respectively. Productivity was further optimized by exploiting the interactions between the constituents of the medium by the response surface method. A partial factorial design, followed by steepest ascent analysis, was carried out to locate the general vicinity of the optimal level of each nutrient. The response surface of AA production in this optimal region was then approximated with a full quadratic equation obtained from a three-factor/five-level central composite rotatable design. Maximum AA yield was predicted to occur in a medium that contained 99.7 g/L of soluble starch, 12.6 g/L of yeast extract, and 3.0 g/L of KH 2 PO 4 . Upon verification, the average experimental yield of AA (3,885 mg/L) was not significantly different from the predicted AA yield (3,940 mg/L), indicating that the response surface method had succeeded in exploiting the AA production potential of this new fungal isolate. JAOCS 74, 569-578 (1997).

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Optimization of arachidonic acid production by Mortierella alpina Wuji‐H4 isolate

Chang

1997

J Americ Oil Chem Soc

“…The addition of only 0.3% KH 2 PO 4 did not enhance the AA production in another experiment involving a jar-fermenter (data not shown). Sajbidor et al (12) used Czapek-mineral, in which calcium is not included. Hansson et al (13) added phosphorus, sodium, calcium, and magnesium for γ-linolenic acid production, but the concentration of the added calcium was much lower than that in our medium.…”

Section: Discussionmentioning

confidence: 99%

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

Higashiyama

Yaguchi

Akimoto

et al. 1998

J Americ Oil Chem Soc

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...

“…Microheterotrophs do not require some of the elements necessary for the culture of autotrophs (e.g., light, carbon dioxide), and some see them as a potential alternative to traditional commercial sources of PUFA. Arachidonic acid has been produced in quantity by some fungi (Sajbidor et al, 1990;Gandhi and Weete, 1991). Certain bacteria have been shown to produce EPA and DHA (Nichols et al, 1993;Jøstensen and Landfald, 1997).…”

Section: Introductionmentioning

confidence: 99%

The Biotechnological Potential of Thraustochytrids

1999

Thraustochytrids are common marine microheterotrophs, taxonomically aligned with heterokont algae. Recent studies have shown that some thraustochytrid strains can be cultured to produce high biomass, containing substantial amounts of lipid rich in polyunsaturated fatty acid (PUFA). It is also evident that cell yield and PUFA production by some thraustochytrid strains can be varied by manipulation of physical and chemical parameters of the culture. At present, fish oils and cultured phototrophic microalgae are the main commercial sources of PUFA. The possible decline of commercial fish stocks and the relatively complex technology required to commercially produce microalgae have prompted research into possible alternative sources of PUFA. The culture of thraustochytrids and other PUFA-producing microheterotrophs is seen as one such alternative. Indeed, several thraustochytrid-based products are already on the market, and research into further applications is continuing. Many fish and microalgal oils currently available have relatively complex PUFA profiles, increasing the cost of preparation of high-purity PUFA oils. In contrast, some of the thraustochytrids examined to date have simpler PUFA profiles. If these or other strains can be grown in sufficient quantities and at an appropriate cost, the use of thraustochytrid-derived oils may decrease the high expense currently involved with producing high-purity microbial oils. As more is learned about the health and nutritional benefits of PUFA, demand for PUFA-rich products is expected to increase. Results to date suggest that thraustochytrids could form an important part in the supply of such products.