S74: Caffeine: A microbial perspective

Caffeine and related alkylxanthines are plant-derived natural products that belong to the purine class of alkaloids.  Human beings consume these molecules in the form of many beverages, especially caffeine.  In contrast, bacteria are able to grow on caffeine as sole source of carbon and nitrogen via total degradation of the molecule.  Pseudomonas putida CBB5 and Pseudomonas sp. CBB1 were isolated from garden soil via enrichment with caffeine as the sole source of carbon and nitrogen.  CBB5 was found to sequentially N-demethylate caffeine and theophylline to xanthine.  A 2-component NADH-dependent N-demethylase (NDM enzyme), comprising a cytochrome c reductase (CCR) and an N-demethylase (NDM protein) has been purified from CBB5.  This enzyme was composed of two subunits based on SDS-PAGE analysis. Interestingly, cloning of the 2-subunits of NDM, Ndm A & B, revealed that they had highly specific 1- and 3-N-demethylase activities respectively.