Conversion of lysine to pipecolic acid by rumen ciliate protozoa

Addition of lysine to the culture medium of rumen ciliates increased the amount of pipecolate in the medium to the level over the control. l-Lysine- U-14C was partly incorporated into ciliate protein unchanged, and partly converted to radioactive pipecolate. The autoradiogram of amino acids in supernatant fluid of the medium revealed the traces of two unidentified spots other than lysine and pipecolate as a main metabolite. Since the radioactive pipecolate was not changed further more by ciliates, it seemed to be the end product in lysine degradation. After addition of l-lysine-α,ε-15N to the medium, 15N was detected mainly in the fractions of pipecolate and ammonia and a little in that of glutamate, alanine and aspartate of the medium.