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item Hou, Ching

Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2006
Publication Date: 8/15/2006
Citation: Hou, C.T. 2006. Monooxygenase system of Bacillus megaterium ALA2: studies on linoleic acid epoxidation products. Applied Microbiology and Biotechnology. 83(8):677-681.

Interpretive Summary: Previously, we discovered a new microbial strain ALA2 that produced seven new polyhydroxy unsaturated fatty acids from linoleic acid. Hydroxy fatty acids are useful as starting materials for the synthesis of specialty chemicals, special military nylon, plastisizers, and coatings materials. Polyhydroxy unsaturated fatty acids are also valuable precursors for prostaglandin and other hormones synthesis, can act as fungicides in agricultural application, are precursors of flavor ingredients, and are chiral synthons of possible drug discovery interest. Application of these new products either for bioactive agents or raw material for synthesis of specialty chemicals will benefit U.S. farmers. We have been trying to improve the products yield through manipulation of metabolic pathway enzymes. Recently, we reclassified strain ALA2 as Bacillus megaterium and we have shown that strain ALA2 enzymes also convert palmitic acid to hydroxyl fatty acids products similar to those well studied self-sufficient cytochrome P450 monooxygenase system in Bacillus strains. Now, we identified the initial epoxidation product from linoleic acid and compared it with the two well studied Bacillus strains. Their epoxidation enzyme systems are also similar. These findings facilitate studies on strain ALA2 oxygenase system.

Technical Abstract: Bacillus megaterium ALA2 produces many oxygenated fatty acids from linoleic acid:12,13-dihydroxy- 9(Z)-octadecenoic acid; 12,13,17-trihydroxy-9(Z)-octadecenoic acid; 12,13,16-trihydroxy-9(z)-octadecenoic acid; 12-hydroxy-13,16-epoxy-9(Z)-octadecenoic acid; and 12,17;13,17-diepoxy-16-hydroxy-9(Z)-octadecenoic acid. Recently, we studied the monooxygenase system of B. megaterium ALA2 by comparing its palmitic acid oxidation products with the well-studied catalytically self-sufficient P450 monooxygenase of B. megaterium ATCC 14581 (NRRL B-3712), and B. subtilis strain 168 (NRRL B-4219) and found that their oxidation products were identical indicating that their monooxygenase systems (hydroxylation) are similar. Now, we report that strain ALA2 epoxidizes linoleic acid to 12,13-epoxy-9(Z)-octadecenoic acid and 9,10-epoxy-12(Z)-octadecenoic acid, the initial products in the linoleic acid oxidation. The epoxidation activity of strain ALA2 was compared with the above mentioned two Bacillus strains. These two Bacillus strain also produced 12,13-epoxy-9(Z)-octadecenoic acid and 9,10-epoxy-12(Z)-octadecenoic acid indicating that their epoxidation enzyme systems might be similar. The ratio of the epoxy fatty acids production by these three strains, strain ALA2: NRRL B-3712: NRRL B-4219 were: for 12,13-epoxy-9(Z)-octadecenoic acid 5.56: 0.66: 0.18 and for 9,10-epoxy-12(Z)-octadecenoic acid 2.43: 0.41: 0.57 per 50 mL medium per 48 hours, respectively.