|Kuo, Tsung Min|
Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2002
Publication Date: 1/15/2003
Citation: Kuo, T., Lanser, A.C. 2003. Factors influencing the production of a novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid by Pseudomonas aeruginosa PR3 (NRRL B-18602) in batch cultures. Current Microbiology. 47:186-191.
Interpretive Summary: U.S. soybean oil production has a large annual surplus of about 1.5 billion pounds. Converting this surplus into new, value-added products would greatly benefit U.S. farmers and the agricultural industry. At the National Center for Agricultural Utilization Research we have examined a number of microbial systems for the conversion of fatty acids found in soybean oil to new products with enhanced functionality. One important reaction involves a bacterial strain PR3, which in small shake flasks converts inexpensive oleic acid, a component of soybean oil, to a novel compound simply called DOD. In this study we evaluated factors that would greatly influence DOD production in a scaled-up 4.5 liter culture medium using a 7 liter bioreactor vessel. Gaining knowledge of these factors led to the development of new process technology to achieve good production of DOD in the bioreactor. DOD in hundred-gram quantities is now available for scientists to explore such new uses as additives for biodiesel fuel, lubricants, coatings, and painting formulations.
Technical Abstract: Pseudomonas aeruginosa PR3 (NRRL B-18602) converts oleic acid to a novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). Parameters that included medium volume, cell growth time, gyration speed, pH, substrate concentration, and dissolved oxygen concentration were evaluated for a scale-up production of DOD in batch cultures using Fernbach flasks and a bench-top bioreactor. Maximum production of about 2 g DOD (38% yield) was attained in Fernbach flasks containing 500 ml medium when cells were grown at 28oC and 300 rpm for 16-20 h and the culture was adjusted to pH 7 prior to substrate addition. Increases of medium volume and substrate concentration failed to enhance yield. When batch cultures were initially conducted in a reactor, excessive foaming occurred that made the bioconversion process inoperable. This was overcome by a new aeration mechanism that provided adequate dissolved oxygen to the fermentation culture. Under the optimal conditions of 650 rpm, 28oC and 40-60% dissolved oxygen concentration, DOD production reached about 40 g (40% yield) in 4.5 L culture media using a 7-L reactor vessel. This is the first report on a successful scale-up production of DOD.