2.2. Screening of thermotolerant yeasts for ethanol
production at high temperature
Screening for high ethanol production was conducted at
40 and 45 C in 250 ml Erlenmeyer flasks containing 100 ml
of a basal sugar cane juice medium composed of sugar cane
juice supplemented with sucrose to 18% total sugars and
0.05% (NH4)2SO4 and with pH adjustment to 4.5 with
1 N HCl. Inocula were prepared by transferring one loop
full of 24 h culture grown on a slant of YPD agar to an
Erlenmeyer flask containing 50 ml of a sugar cane juice
medium as above but with only 2% total sugars. After incubation
on a rotary shaker at 25–28 C for 24 h, the inocula
were transferred at the rate of 5% to the screening medium,
followed by incubation on a rotary shaker at 40 and 45 C.