Hydrogenation of Unsaturated Fatty Acids by Treponema ( Borrelia ) Strain B 2 5, a Rumen Spirochete

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Abstract
The time course of hydrogenation of linoleic acid to trans -11-octadecenoic acid was observed in a growing culture of Treponema ( Borrelia ) strain B 2 5. A conjugated fatty acid, cis -9, trans -11-octadecadienoic acid, was identified as an intermediate in the process. The isomerase responsible for the conversion of linoleic acid to the conjugated fatty acid was found to be associated with a particulate fraction characterized by a high protein and lipid content in a 2:1 ratio. Optimum p H for isomerase activity was found to be 7.0 in 0.05 m potassium phosphate buffer. No cofactor requirements could be demonstrated for the isomerase. The sulfhydryl inhibiting agents, iodoacetamide, N -ethylmaleimide, and p -chloromercuribenzoate, inhibited isomerase activity. Isomerase activity was also inhibited by the metal chelators, o -phenanthroline, α, α′-bipyridyl, ethylenediaminetetraacetic acid, and 8-hydroxyquinoline. Linoleic (Δ9, 12), linolenic (Δ9, 12, 15), and gamma-linolenic (Δ6, 9, 12) acids served as effective substrates for the isomerase; however, the derivatives of linoleic and linolenic acid did not.