DEGRADATION OF CAFFEINE AND RELATED METHYLXANTHINES BY SERRATIA-MARCESCENS ISOLATED FROM SOIL UNDER COFFEE CULTIVATION

A strain of Serratia marcescens showing the ability to degrade caffein e and other methylxanthines was isolated from soil under coffee cultiv ation. Growth was observed only with xanthines methylated at the 7 pos ition (caffeine, 1,3,7-trimethylxanthine; paraxanthine, 1,7-dimethylxa nthine; theobromine, 3,7-dimethylxanthine and 7-methylxanthine). Parax anthine and theobromine were released in liquid medium when caffeine w as used as the sole source of carbon and nitrogen. When paraxanthine o r theobromine were used, 3-methylxanthine, 7-methylxanthine, and xanth ine were detected in the Liquid medium. Serratia marcescens did not gr ow with theophylline (1,3-dimethylxanthine), l-methylxanthine, and 3-m ethylxanthine, and poor growth was observed with xanthine. Methyluric acid formation from methylxanthines was tested in cell-free extracts b y measuring dehydrogenase reduction of tetrazolium salt in native-poly acrylamide gel electrophoresis gel. Activity was observed for all meth ylxanthines, even those with which no bacterial growth was observed. O ur results suggest that in this strain of S. marcescens caffeine is de graded to theobromine (3,7-dimethylxanthine) and/or paraxanthine (1,7- dimethylxanthine), and subsequently to 7-methylxanthine and xanthine. Methyluric acid formation could not be confirmed.