ARGININE METABOLISM IN PLEUROPNEUMONIA-LIKE ORGANISMS ISOLATED FROM MAMMALIAN CELL CULTURE

Abstract

Arginine degradation is a significant metabolic process for pleuropneumonia-like organisms (PPLO; Mycoplasma) isolated from cell culture. The conversion of arginine to ornithine in PPLO-contaminated cell culture was rapid, and occurred by the arginine dihydrolase pathway involving arginine deiminase, ornithine transcarbamylase and carbamyl phosphokinase. In the absence of PPLO contamination, arginine conversion to ornithine was minimal and took place by an arginase activity present in the cell culture but not in the PPLO. All five PPLO strains isolated from cell culture accomplished the conversion of arginine to ornithine and contained the requisite enzyme of the arginine dihydrolase system, whereas PPLO-free cell cultures did not. Supplementation of PPLO culture broth with arginine increased the extent of PPLO growth. When the arginine content of the culture limited growth, arginine was completely converted to ornithine. When growth was limited in the presence of excess arginine, citrulline was the major breakdown product. It is suggested that the conversion of arginine to ornithine constitutes a significant and possible major source of adenosine triphosphate for this class of organisms.