Yeast S. cerevisiae MTCC 174 was purchased from IMTEC, India and Pichia stipitis National Collection of Industrial Microorganism (NCIM) no. 3497 [the genus name Pichia has been changed to Scheffersomyces (Kurtzman and Suzuki 2010) so S. stipitis name is used in present study instead of P. stipitis] from NCIM National Chemical laboratory, Pune, Maharashtra, India.