|Kuo, Tsung Min|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 14, 2003
Publication Date: N/A
Technical Abstract: We research to apply new microbial systems for converting soybean oil and its component fatty acids to valuable industrial products and to develop effective scale-up processes for producing these compounds. A number of reactive strains were identified from the soil and water samples collected in various geographic locations, the composted materials undergone an enrichment strategy using specific fatty acids as selection agents, and the ARS Culture Collection. Three of them were subjected to scale-up production studies including a Pseudomonas aeruginosa (NRRL B-18602) isolated from a pig-farm water sample to convert oleic acid to 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) and ricinoleic acid to 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD), a Sphingobacterium thalpophilum (NRRL B-14797) isolated from composts by an enrichment selection technique to convert oleic acid to solely 10-hydroxystearic acid (10-HSA), and a Bacillus sphaericus (NRRL NRS-732) from the ARS Culture Collection to convert oleic acid to solely 10 ketostearic acid (10-KSA). In the production of DOD in a 7-L stirred batch reactor, excessive foaming was controlled by a new aeration mechanism in which airflow into the reactor was supplied continuously from the top through two ports on the headplate and periodically through a bottom sparger, in conjunction with the use of marine impellers for agitation. To further increase the production yield of a bioconversion system, we examined the effects of commercial fermentation defoamers, such as Biospumex 153 K, Clerol FBA 975, Clerol FBA 3107, and Clerol FBA 5059 from Cognis Corp. (Cincinnati, OH), in addition to using the unique aeration arrangement. It was found in small shaken flask experiments that the bioconversion yield is generally higher when a defoamer was added to the culture broth at the time of adding fatty acid substrate than it was added early in the medium preparation and Biospumex 153 K was most effective among the four defoamers examined. This defoamer was thus applied to the reactor processes during the production of 10-HSA and 10-KSA. As a concentration of 400 ppm defoamer was added to 1-L medium in a 2-L reactor, the yield of 10-HSA by NRRL B-14797 was increased to 7.1 g (39.4%) in 4-d from 5.2 g (28.9%) without the defoamer, whereas the yield of 10-KSA by NRRL NRS-732 was decreased from 1.5 g (8.3%) to 0.4 g (2.2%) in 5-d. The results indicate that the effectiveness of a defoamer may also depend on different bioconversion systems. Further defoamer evaluation is in progress and we will also examine a unique emulsification technology developed by Cognis scientists for the delivery of hydrophobic fatty acid substrates to the reactor.