Identification of S. cerevisiae strains with thermotolerance in AFEX corn stover hydrolysate (ACSH). (A) Heat map displaying binned growth phenotypes of 108 wild and domesticated S. cerevisiae strains grown in the indicated media at 40°C. Yeast strains were grown in 96-well plate format on 6% or 9% glucan loading (GL) ACSH at 40°C, or YEPD at 30 or 40°C for 24 hours. Cell growth was continuously monitored by measuring the optical density at 595 nm every 10 minutes with Tecan 96-well plate readers. Specific growth rates in ACSH or YEPD at 40°C were normalized relative to YEPD at 30°C, and resulting values were binned (0–0.2 = “No growth,” 0.2-0.4 = “Slow” growth, 0.4-0.8 = “Moderate” growth, >0.8 = “Fast” growth). Strains were placed into numbered cluster groups (1–7) and the number of strains within each group are indicated along the right side of the heat map based on phenotype and is indicated in the Additional file 1: Table S1. Representative 96-well growth curve data of CEN.PK2 (B), ATCC4124 (C) or GLBRCY0 (D) in indicated media conditions. Relative cell densities are expressed as background subtracted OD595 values divided by the initial OD595 value for each culture. Time points every 30 minutes are shown for clarity.