Monooxygenase system of Bacillus megaterium ALA2: Studies on linoleic acid epoxidation products

Bacillus megaterium ALA2 produces many oxygenated FA 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 those of the well-studied catalytically self-sufficient P450 monooxygenase of B. megaterium ATCC 14581 (NRRL B-3712) and of B. subtilis strain 168 (NRRI B-4219). We found that their oxidation products are 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 enzyme did not oxidize specific double bond of the linoleic acid. The epoxidation activity of strain ALA2 was compared with the above-mentioned two Bacillus strains. These two Bacillus strain also produced 12,13-expoxy-9 (Z)-octadecenoic acid and 9,10-epoxy-12(Z)-octadecenoic acid, indicating that their epoxidation enzyme systems might be similar. The ratios of epoxy FA production by these three strains (A1 A2, NRRI B-3712, and NRRI B-4219) were, respectively, 5.56∶0.66∶0.18 for 12,13-epoxy-9(Z)-octadecenoic acid and 2.43∶0.41∶0.57 for 9,10-epoxy-12(Z)-octadecenoic acid per 50 mL medium per 48 h.