Detection of End Products of the Arginine Dihydrolase Pathway in Both Fermentative and Nonfermentative Mycoplasma Species by Thin-Layer Chromatography

Abstract

A total of 22 species of the order Mycoplasmatales, representing eight serologically distinct groups, were tested for the presence of the first two enzymes of the arginine dihydrolase pathway by using two-dimensional thin-layer chromatography to separate end products. Both citrulline, produced by arginine deiminase, and ornithine, produced by ornithine carbamoyltransferase, were found in the glycolytic serogroup 1 species Mycoplasmu putrefaciens, Mycoplasma capricolum, and Mycoplasma sp. bovine group 7, in Mycoplasma fermentans (serogroup 6), and in the nonferrnentative serogroup 7 species Mycoplasma arginini, Mycoplasma hominis, Mycophsma gallinarum, Mycoplasma gateae, Mycoplasma salivarium, Mycoplasma orale, and Mycoplasma buccale. Citrulline alone was found in one glycolytic species, Mycoplasma gallisepticum (serogroup 4). No end products were found in six other fermentative Mycoplasma species, in three Acholeplasma species, or in two Ureaplasma urealyticum serovars. The use of radiolabeled substrate with representative species showed that citrulline and ornithine were produced from arginine and not derived from the medium.The genus Mycoplasma is taxonomically unusual in that, unlike most bacterial genera (23), it includes both fermentative and nonfermentative species (19). Most Mycoplasma species which do not ferment glucose reportedly metabolize arginine via the arginine dihydrolase pathway (6). A few species metabolize both glucose and arginine, while even fewer seem to use neither substrate (4, 19). The microbial arginine dihydrolase pathway involves three enzyme reactions; arginine is converted into citrulline and ammonia by arginine deiminase, and this is followed by conversion of citrulline plus phosphate ion into ornithine and carbamyl phosphate by catabolic ornithine carbamolytransferase. Finally, a phosphate group is transferred from carbamyl phosphate to adenosine diphosphate (to form adenosine triphosphate) with the concomitant release of carbon dioxide and almmonia by carbamate kinase (1). The arginine dihydrolase pathway is usually detected by observation of an alkaline shift in the pH of medium containing added arginine (2, 4). This elevation of the pH is caused by the release of 2 mol of WH3 when 1 mol of arginine is converted via citrulline to ornithine, NH3, and COZ. In species which use both glucose and arginine, such as Mycoplasma fermentans (9, the pH change is unpredictable because of competition between acid production from sugar fermentation and NH3 release from arginine (2). Therefore, specific detection of the reaction products, citrulline and ornithine, may be necessary to show that the arginine dihydrolase pathway is present. Detection of citrulline is especially important, because the production of citrulline from arginine is unique to the arginine dihydrolase pathway, whereas ornithine may arise from arginine by other pathways, including the arginase and arginine transamidinase pathways (1). Both arginine deiminase and ornithine carbamoyltransferase activities have been documente...

Determination of metabolic activity in planktonic and biofilm cells of Mycoplasma fermentans and Mycoplasma pneumoniae by nuclear magnetic resonance

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Reconstitution of an Active Arginine Deiminase Pathway in Mycoplasma pneumoniae M129

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Differences in Accumulation of Radiolabeled Amino Acids and Polyamines by Mycoplasma and Acholeplasma Species

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