Microcalorimetric study of <Emphasis Type=?Italic?>Bacillus thuringiensis</Emphasis> growth with different plasmid numbers and various promoters

Abstract

A microcalorimetric technique was used to investigate the influence of plasmid copy number and various promoters on the green fluorescent protein expression in Bacillus thuringiensis. The power-time curves of the growth metabolism of B. thuringiensis have been determined by using an LKB-2277 bioactivity monitor at 28°C. For evaluation of the results, the maximum peak-heat output power ( P max ), the generation time ( t G ), the growth rate constants ( k ) in the log phase, the total heat effect ( Q total ) for the growth metabolism of Bacillus thuringiensis were determined. The results firstly indicated that the more plasmid copy number per cell the more protein synthesization, and promoter BtI-BtII had a stronger impact on the gene expression than promoter 3A investigated by the method of microcalorimetry.