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.