Monday, May 4, 2009
9-70
Effect of higher culture temperature on the metabolism of Escherichia coli
Chowdhury Mohammad Monirul Hasan, Department of Bioscience and Bioinformatics, Kyushu Istitute of Technology (KIT), Japan, Aida, 294-9, Room, 402,Iizuka shi, Iizuka, Fakuoka., Iizuka, Fakuoka, Japan
Biofuels have been paid recent attention from the view point of energy generation from biomass. Among the biofuel process, simultaneous saccarification and fermentation (SSF) is now being paid more attention. In SSF, the culture temperature has to be increased more than 40°C. Escherichia coli, as all kind of organisms, responds to the increase of the temperature by inducing heat shock proteins etc. So the objective is to investigate the effect of higher temperature on the metabolism in Escherichia coli from the view point of gene expressions.
The strains used were E. coli BW25113. Batch and continuous cultivations were made using 2- L fermentor where the temperature was kept constant either at 37°C or 42°C, and the pH of the culture was maintained at 7.0. Continuous cultivation was performed at the dilution rate of 0.2 h-1. Qiagen RNeasy® Mini Kit was used to isolate total RNA from E.coli cells according to the manufacturer’s recommendation. After the temperature up-shift the lpdA gene which codes for the (lipopolyamide dehydrogenase) subunit of the pyruvate dehydrogenase (PDHc) complex was induced due to the up-regulation of cAMP receptor protein (CRP) .Our results also indicate that global regulator arcA as well as heat shock protein genes were up regulated which in turn repressed such genes as icdA, aceA, sucA, cyoA while cydB were up regulated under higher temperature as compared with the lower temperature. This caused the repression of TCA cycle activity and in turns caused higher acetate production at higher temperature.
The strains used were E. coli BW25113. Batch and continuous cultivations were made using 2- L fermentor where the temperature was kept constant either at 37°C or 42°C, and the pH of the culture was maintained at 7.0. Continuous cultivation was performed at the dilution rate of 0.2 h-1. Qiagen RNeasy® Mini Kit was used to isolate total RNA from E.coli cells according to the manufacturer’s recommendation. After the temperature up-shift the lpdA gene which codes for the (lipopolyamide dehydrogenase) subunit of the pyruvate dehydrogenase (PDHc) complex was induced due to the up-regulation of cAMP receptor protein (CRP) .Our results also indicate that global regulator arcA as well as heat shock protein genes were up regulated which in turn repressed such genes as icdA, aceA, sucA, cyoA while cydB were up regulated under higher temperature as compared with the lower temperature. This caused the repression of TCA cycle activity and in turns caused higher acetate production at higher temperature.