Anaerobic Purine Dissimilation by Washed Suspensions of Bovine Rumen Bacteria

Xanthine, uric acid, and guanine hydrochloride were degraded completely, at a slow rate, by WCS of bovine tureen baeteria. The end-products formed were carbon dioxide, ammonia, and acetic acid, and the fermentation pattern was similar to that observed in elostridial-type organisms. Hypoxanthine was degraded incmnpletely, wherea:~ adenine was neither deearboxylated nor deaminated under the conditions employed. Gases other than earbon dioxide (hydrogen and/or methane) never were encountered as end-products of purine degradation and neither were lactic, formic, propicnic, and butyrie adds. With the exception of hypoxanthine, WCS deaminated purines to a greater extent under alkaline than under acidic conditions. In experiments dealing' with xanthine decarhoxylation, less carbon dioxide was formed from this substrate than that observed for the corresponding endogenous wflue. This was not true of other purines. Kinetic treatment of the data suggested ttmt a (,m'bon dioxide utilizing or fixing mechanism was involw,d in xmlthine dissimilation. Purine intereonversi(ms vould not be demonstrated by pal)er ehr(mmtogral)hy, l)ifferential speetrophotometrie methods showed that xanthine mM uric acid were degraded coml>letely , hyIi<)xmlthine was partially degraded, and adenine was not dissimilated. l'urines are known constituents of plants and they exist in the free state or hound as mwleosides or mwleotides. Ferguson and Terry (11) reported the presem'e of lmrim~s in grassland herbage, i.e., adenine, guanine, xanthine, and hypoxanthine. The nonprotein nitrogen content of grassland herbage represents from 15 to 20% of the total nitrogen present, and from 511 to 60% of the nonprotein nitrogen fraction is ammonia, nitrate, avid amides, aml amino acids. The remaimler consists of puriues, possible pyrimidines, either free or bound ( tt ). Guanine aud adenine, well-known constituents of nucleic acids, haw, been found in the free state in alfalfa leaves (28,). Itypoxanthine, xanthine, and uric avid occur primarily in the free state, and uric aeid hits been observed in leaves aim seeds in concentrations (if 250 lng. per kilogram (12). Therefore, free or boumt purines are, in fact, ingested in feeds given to rmninams. Experiments were undertaken to determine to what extent catabolic activity was exhibited by washed cell suspensions (WCS) of bovine rumen baeteria on this g'roup of eolnpotlnds.