Catabolic pathways and biotechnological applications of microbial caffeine degradation

Abstract

Catabolism of caffeine (1,3,7-trimethylxanthine) in microorganisms commences via two possible mechanisms: demethylation and oxidation. Through the demethylation route, the major metabolite formed in fungi is theophylline (1,3-dimethylxanthine), whereas theobromine (3,7-dimethylxanthine) is the major metabolite in bacteria. In certain bacterial species, caffeine has also been oxidized directly to trimethyl uric acid in a single step. The conversion of caffeine to its metabolites is primarily brought about by N-demethylases (such as caffeine demethylase, theobromine demethylase and heteroxanthinedemethylase), caffeine oxidase and xanthine oxidase that are produced by several caffeine-degrading bacterial species such as Pseudomonas putida and species within the genera Alcaligenes, Rhodococcus and Klebsiella. Development of biodecaffeination techniques using these enzymes or using whole cells offers an attractive alternative to the present existing chemical and physical methods removal of caffeine, which are costly, toxic and non-specific to caffeine. This review mainly focuses on the biochemistry of microbial caffeine degradation, presenting recent advances and the potential biotechnological application of caffeine-degrading enzymes.

Characterization of a broad-specificity non-haem iron N-demethylase from Pseudomonas putida CBB5 capable of utilizing several purine alkaloids as sole carbon and nitrogen source

“…Paraxanthine and theobromine are further N-demethylated to 7-methylxanthine and xanthine. Xanthine is subsequently oxidized to uric acid by xanthine oxidase/dehydrogenase, and the uric acid enters the normal purine catabolic pathway to form CO 2 and NH z 4 (Dash & Gummadi, 2006). Theophylline, the major caffeine metabolite in filamentous fungi (Hakil et al, 1998), has not been reported as a bacterial metabolite of caffeine.…”

Two Distinct Pathways for Metabolism of Theophylline and Caffeine Are Coexpressed in Pseudomonas putida CBB5

“…Caffeine is also a major human dietary ingredient that can be found in common beverages and food products, such as coffee, tea, and chocolates. In pharmaceuticals, caffeine is used generally as a cardiac, neurological, and respiratory stimulant, as well as a diuretic (3). Hence, caffeine and related methylxanthines enter soil and water easily through decomposed plant materials and other means, such as effluents from coffee-and tea-processing facilities.…”

“…Hence, caffeine and related methylxanthines enter soil and water easily through decomposed plant materials and other means, such as effluents from coffee-and tea-processing facilities. Therefore, it is not surprising that microorganisms capable of degrading caffeine have been isolated from various natural environments, with or without enrichment procedures (3,10). Bacteria use oxidative and N-demethylating pathways for catabolism of caffeine.…”

“…Subsequent N demethylation of theobromine or paraxanthine to xanthine is via 7-methyxanthine. Xanthine is further oxidized to uric acid by xanthine dehydrogenase/oxidase (3,10). Although the identities of metabolites and the sequence of metabolite formation for caffeine N demethylation are well established, there is very little information on the number and nature of N-demethylases involved in this pathway.…”

Characterization of microbial communities in wetland mesocosms receiving caffeine-enriched wastewater

“…On the other hand, other members of the microbial community may be reduced in abundance whether that be they are outcompeted (i.e., caffeine serves as food source for other species) or sensitive (i.e., caffeine acts as an antimicrobial). It has been reported in earlier studies that caffeine at a relatively low concentration was antimicrobial and resulted in inhibition of growth and death of bacterial strains like E. coli and other bacterial strains particularly upon addition of caffeine at log phase of growth (Dash and Gummadi 2006;Gummadi et al 2012). Indeed, Ramanavièienë et al (2002) found that the growth of E. coli was inhibited significantly at caffeine concentrations as low as 1 g/L.…”