• KSBB Journal
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• v.24 no.1
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• pp.41-46
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• 2009

Vegetable oils are desirable inexpensive feedstocks for various bioproducts. The content of unsaturated fatty acids such as oleic and linoleic acids are 22% and 55% for soybean oil, 26% and 60% for corn oil, and 61% and 21% for canola oil, respectively. Keto and hydroxy fatty acids are useful industrial chemicals, used in plasticizer, surfactant, lubricant and detergent formulations because of their special chemical properties such as higher viscosity and reactivity compared with other fatty acids. In this study, a microbial isolate, Flavobacterium sp. strain DS5 (NRRL B-14859), was used to convert oleic acid to 10-ketostearic acid (10-KSA) via 10-hydroxystearic acid (10-HSA). Two bioconversion products, 10-KSA and 10-HSA, were quantitatively and qualitatively analyzed using gas chromatography, gas chromatography-mass spectrometry, and $^1H-$ and $^{13}C$-nuclear magnetic resonance. The maximum production of 10-KSA and 10-HSA in flask cultures were 3.4 g/L and 0.5 g/L, respectively. The optimum concentrations of glucose and yeast extract, addition time and volume of oleic acid for 10-KSA production were less than 20 g/L, more than 5 g/L, 18 hand 0.3 ml/50 ml, respectively.

• Korean journal of applied entomology
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• v.55 no.2
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• pp.129-138
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• 2016

Eicosanoids are a group of C20 oxygenated polyunsaturated fatty acids (PUFAs). To monitor biosynthetic precursors of these PUFAs, this study extracted fatty acids from different tissues of the beet armyworm, Spodoptera exigua, and assessed their compositions using GC/MS. Fifth instar larvae were dissected to isolate different tissues of gut, fat body, hemocytes, and integument. From each tissue, total lipids were extracted and fractionated into neutral lipid (NL), glycolipid (GL), and phospholipid (PL). Most tissues contained palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3). However, their compositions were different among tissues and lipid types. Fat body and hemocytes possessed other type of fatty acids such as myristic acid (14:0) and three unknown fatty acids. Among lipid types, PL contained relatively high levels of linolenic acid than NL and GL, while it had lower saturated fatty acids. Total unsaturated fatty acid composition was varied among tissues and lipid types. PL was rich in unsaturated fatty acids in fat body, gut, and hemocytes. There was a significant influence of calcium-independent phospholipase $A_2$ ($iPLA_2$) on maintaining fatty acid composition because RNA interference of $iPLA_2$ expression significantly modified fatty acid compositions in NL and PL. However, this study did not detect arachidonic acid, a main eicosanoid biosynthesis precursor, in all tissues. This suggests an alternative biosynthesis of eicosanoids in insects, which is distinct from the biosynthetic pathway of mammals.