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