ISSN:
1432-072X
Keywords:
Thermophilic bacteria
;
B. stearothermophilus
;
B. caldotenax
;
Thermophilic (Thermostable) Enzymes
;
Adaptation
;
Thermoadaptation of Enzymes
;
Thermoadaptation of Bacteria
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract 1. Bacillus stearothermophilus was adapted to 37° C (mesophilic culture) and to 55° C (thermophilic culture) by cultivation via an intermediate temperature of 46° C. In the crude extract of the thermophilic bacterial cells the glucokinase, glucose-6-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and isocitrate dehydrogenase are more thermostable than the corresponding enzymes in the crude extract of mesophilic cells. At the intermediate temperature of 46° C both types are probably formed. 2. 37° C-precultures of Bacillus caldotenax were further cultivated (in different samples) at 5° C intervals between 30° C and 70° C. It was shown that in 70° C-cells of the above mentioned enzymes more thermostable forms and in 37° C-cells more thermolabile forms are present. Furthermore, as demonstrated in the case of glucose-6-phosphate isomerase and isocitrate dehydrogenase, cells cultured in the temperature range between 30–50° C produced thermolabile enzyme variants (M-type), while cultures between 60–70° C produced thermostable variants (Th-type). At cultivation temperatures above 50° C a pronounced lag-period expressing the metabolic changes was found. In the lag-period, mesophilic enzymes are no longer present as early as 20 min after increasing the temperature (70° C), and synthesis of thermostable enzymes starts about 1 h before the beginning of growth. 3. Similar results were obtained with Bacillus caldotenax precultivated at 70° C and cultivated between 30° C and 70° C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00425289
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