BIOCATALYTIC PRODUCTION OF 10-HYDROXYSTEARIC ACID, 10-KETOSTEARIC ACID AND THEIR PRIMARY FATTY AMIDES

Authors: Kuo, Tsung Min; Levinson, William

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2006
Publication Date: 7/15/2006
Citation: Kuo, T., Levinson, W.E. 2006. Biocatalytic production of 10-hydroxystearic acid, 10-ketostearic acid and their primary fatty amides. Journal of the American Oil Chemists' Society. 83(8): 671-675.

Interpretive Summary: Surplus vegetable oils represent attractive renewable resources for the production of useful chemicals. We are investigating microbial conversion of vegetable oils and their component fatty acids for producing value-added products. Oleic acid common in vegetable oils can be converted in most known reactions to produce a mixture of two new oxygenated compounds useful in certain lubricants, coatings, and grease formulations. In our laboratories, we previously found two novel microbial strains that each produce a single type of oxygenated compound, which will facilitate purification. In this study, we improved the microbial conversion reactions and developed a scale-up reactor process for producing these compounds using crude grades of oleic acid. We further modified the oxygenated compounds by directly adding ammonia to one reactive terminus by use of a microbial enzyme to form new compounds called fatty amides with new properties. The impact of this study provides basic information and technology for scientists to develop bioprocesses for producing similar types of new compounds from low cost vegetable oils.

Technical Abstract: Most microbial hydration reactions of oleic acid produce a mixture of 10-hydroxystearic acid (10-HSA) and 10-ketostearic acid (10-KSA), which complicates the purification process. A reactor process study was conducted to obtain these compounds in sufficient quantity using Sphingobacterium thalpophilum (NRRL B-14797) and Bacillus sphaericus (NRRL NRS-732), which solely produce 10-HSA and 10-KSA, respectively. Using an 8-h-old B-14797 culture grown in a manganese-containing WF6 medium, pH 7.3, at 28 deg C under 350 rpm agitation and 0–50% dissolved oxygen concentrations provided by a controlled sparger aeration, the production of 10-HSA reached 7 g/L with a 40% yield in 4 days. Using a 12-h-old NRS-732 culture grown in a pyruvate-containing PF6 medium, pH 6.5, at 30 deg C under 750 rpm agitation without any sparger aeration during the conversion reaction, 10-KSA production reached about 10 g with a yield of more than 54% in 72 h. The scale-up reactor process provided crystalline 10-HSA and 10-KSA for producing new primary amides via a lipase-catalyzed amidation reaction with a yield of 94 and 92%, respectively. The primary amides of 10-HSA and 10-KSA displayed high melting points of 115 and 120 deg C, respectively.