ARS | Publication request: MICROBIAL CONVERSION OF RICINOLEIC ACID FOR PRODUCING 7,10,12-TRIHYDROXY-8(E)-OCTADECENOIC ACID, A NATURAL FUNGICIDE FOR TREATMENT OF RICE

Submitted to: Great Lakes Regional American Chemical Society Symposium
Publication Type: Abstract
Publication Acceptance Date: October 17, 2004
Publication Date: October 20, 2004
Citation: Kuo, T., Ray, K.J., Levinson, W.E., Knothe, G.H. 2004. Microbial conversion of ricinoleic acid for producing 7,10,12-trihydroxy-8(e)-octadecenoic acid, a natural fungicide for treatment of rice [abstract]. Great Lakes Regional American Chemical Society Symposium. Peoria IL. p. 186.

Technical Abstract: 7,10,12-Trihydroxy-8(E)-octadecenoic acid (7,10,12-THOD), a novel fungicide especially active against the rice blast fungus, was produced from bioconversion of ricinoleic acid (RA) in small shake flasks. Conversion of RA was examined for sixteen strains of P. aeruginosa including the patented NRRL B-18602, three recent isolates from composted materials, and twelve isolates obtained from the ARS Culture Collection. Strain NRRL B-23260 was one of the best 7,10,12-THOD producers. The bioconversion was carried out in a 2-L reactor using crude RA prepared from saponification of castor oil and strain NRRL B-23260 to produce 7,10,12-THOD in sufficient quantities for testing of industrial uses and to determine its properties for new uses. The reactor process employed a unique aeration mechanism, which involved a filtered airflow constantly supplied from the top through two ports on the headplate and at varied rates as regulated through a bottom sparger to control foaming and a new agitation device, which combined a marine impeller and an open turbine, to overcome the early phase of oxygen depletion and enhance production yields. A yield of 40% was achieved after 77 h of reaction when down-stream processing of the bioproduct was most suitable. 7,10,12-THOD was crystallized from ethyl acetate extracts of the reactor broth following a sequential cooling process to about -20 degrees C. 7,10,12-THOD was found to exhibit a unique surface-active property for potential new uses. Evaluation of new biological activity is in progress through industrial collaborators. This study has provided basic information useful for further developing production processes suitable for commercial uses of 7,10,12-THOD.