Theobromine-degrading potential of yeast strain isolated from tomato (Lycopersicon esculentum) fruit

Abstract

At high dietary concentrations of cocoa (Theobroma cacao) pod husk, theobromine exerts deleterious effects on animals, thereby limiting the utilization of the husk as animal feed. The development of simple and efficient procedures for the elimination of the methylxanthine from the husk would be of tremendous benefit to both the cocoa and animal production sectors. Investigations aimed at sourcing for biological agents suitable for the detheobromination of cocoa pod husk resulted in the isolation of a yeast strain from tomato (Lycopersicon esculentum) fruit. The isolate was biochemically, physiologically and morphologically characterized and identified as Candida krusei. The dependence of its growth on pH, carbon and nitrogen sources was studied. Optimal pH was found to be 5.5. Growth was most vigorous when glucose was used as a source of carbon. Isocratic reversed-phase HPLC using 0.01 M KH2P04: methanol (88:12; v/v) with UV detection was performed to identify theobromine metabolites. Demethylation at position 3 appears to be a major catabolic route for theobromine in the yeast isolate. The isolate holds promise as a tool for the biodetheobromination of cocoa pod husk. Further investigation into its ability to completely utilize theobromine is a subject of ongoing research in our group. © 2012 Academic Journals Inc.