Study On Thermal Adaptation Geobacillus Stearothermophilus CHB1

Thermophillues is a kind of microorganisms living in the high temperature environment and these microorganisms have great application values on genetic engineering, enzyme engineering, mineral engineering and garbage disposal. Moreover, the mechanism how to adapt the high-temperature environment of the thermophillues is a question attracting many researchers.This study examined the thermophilic degree of Geobacillus stearothermophilus CHB1preserved by our laboratory. Under liquid fermentation conditions the minimum growth temperature of CHB1is higher than48℃, the maximum growth temperature is74℃, optimum temperature55℃-65℃, which is an extremely thermophilic bacteria.In order to explore the thermoadaptation mechanism of CHB1, a proteomic technique is used to compare proteome expression of CHB1treated at50and70, and8differental proteins are found. Four of these proteins are identified successfully and the two are hypothetical proteins.Four proteins are ATP-dependent Clp protease proteolytic subunit ClpP, periplasmic serine protease DO(HtrA protease), Alcohol dehydrogenase zinc-binding domain protein and Histidinol phosphate/aromatic aminotransf erase. Two hypothetical proteins are paraquat-inducible protein B and O-methyltransferase.Of all the proteins identified ClpP and HtrA proteasea are heat shock proteins having close relations with thermoadaptation of thermophilic organism. Alcohol dehydrogenase zinc-binding domain protein and Histidinol-phos phate/aromatic aminotransf erase are metabolic enzymes.By comparing the membrane fatty acids in PLFA profiles of CHB1under60℃50℃,70℃processing, membrane fatty acids found in CHB1are nearly all saturated fatty acids,and almost have no change in the proportion of unsaturated fatty acids under three temperatures.This phenomenon reflect the natural thermoadaptation mechanism of CHB1.But, with increasing temperature the proportion of long-chain saturated fatty acids significantly increased, Short chain saturated fatty acids proportion declined.indicating rely mainly on increasing carbon chain length to adapt to higher temperatures stress.