Saccharomyces cerevisiae TFS9, a novel isolated yeast capable of high caffeine-tolerant and its application in biodecaffeination approach

There is a great call for using microbial bio-decaffeination approach to remove caffeine from caffeinated products and industrial wastes. We aimed in this study to screen strains of yeasts which exhibit high caffeine tolerance and to investigate the bio-degradation of caffeine under growth conditions. Sixteen yeast strains were isolated from the cultivated tea soils collected from sites of northern Iran and evaluated for the caffeine tolerance by the agar dilution method. Based on the tolerance efficiency, strain TFS9 was selected and identified as Saccharomyces cerevisiae TFS9 (GenBank accession number KF414526) on the morphological and bioochemical characteristics as well as molecular phylogenetic studies based on amplification the ITS1–5.8S–ITS2 rDNA sequences. The time course of caffeine removal by growing cells of the strain TFS9 in the minimal salt medium containing caffeine as the sole source of carbon was estimated by a decrease in caffeine absorbance using UV-visible spectrophotometer. The concentration of caffeine in the supernatant of the yeast culture medium decreased by 84.8% (from 3.5g/l to 0.53 g/l) after 60h of incubation by using of S. cerevisiae TFS9, without additional optimization process. Results of experimental studies suggest a simple and cost-effective process for the microbial decaffeination of caffeine-containing solutions, and provide a promising approach for developing safe processes that can be used effectively for decaffeination of industrial effluents. The present study provides the first evidence on the caffeine bio-degradation using yeast species of S. cerevisiae.