ACQUIRED THERMOTOLERANCE AND HEAT-SHOCK PROTEINS IN THERMOPHILES FROMTHE 3 PHYLOGENETIC DOMAINS

Thermophilic organisms from each of the three phylogenetic domains (Ba cteria, Archaea, and Eucarya) acquired thermotolerance after heat shoc k. Bacillus caldolyticus grown at 60 degrees C and heat shocked at 69 degrees C for 10 min showed thermotolerance at 74 degrees C, Sulfolobu s shibatae grown at 70 degrees C and heat shocked at 88 degrees C for 60 min show ed thermotolerance at 95 degrees C, and Thermomyces lanugi nosus grown at 50 degrees C and heat shocked at 55 degrees C for 60 mi n showed thermotolerance at 58 degrees C. Determinations of protein sy nthesis during heat shock revealed differences in the dominant heat sh ock proteins for each species. For B. caldolyticus, a 70-kDa protein d ominated while for S. shibatae, a 55-kDa protein dominated and for T. lanuginosus, 31- to 33-kDa proteins dominated. Reagents that disrupted normal protein synthesis during heat shock prevented the enhanced the rmotolerance.