Formation of Lysine from α, ε-Diaminopimelic Acid and Negligible Synthesis of Lysine from Some Other Precursors by Rumen Ciliate Protozoa

Abstract

The possibility of lysine formation from α, e-diaminopimelate (DAP), acetate, aspartate or α-aminoadipate (AAA) in rumen ciliates was examined. DAP-1, 7-14C added to the medium was decarboxylated and converted to radioactive lysine in great amounts and radioactive pipecolate in small amounts by rumen ciliates. Difference of the ability to form lysine from DAP between genus Entodinium and Diplodinium was not observed. With sodium acetate-U-14C, amino acids fraction of the supernatant fluid of the incubation medium and ciliates contained only 0.56 and 0.59% of the total radioactivity, respectively. In the case of L-aspartate-U-14C, 95.1% of the radioactivity of the supernatant fluid desalted and 62.2% of the radioactivity incorporated into ciliates (1.5% of the total radioactivity) remained as aspartate. Autoradiograms revealed the negligible spots of lysine in ciliates in both cases. AAA-6-14C remained almost unchanged, even after incubation with rumen ciliates.