STUDIES ON THE GROWTH METABOLISM OF Bacillus thuringiensis AND ITS VEGETATIVE INSECTICIDAL PROTEIN ENGINEERED STRAINS BY MICROCALORIMETRY

摘要

The metabolic power-times curves of Bacillus thuringiensis and its vegetative insecticidal protein engineered strains were determined at 30°C by using a thermal activity monitor air Isothermal Microcalorimeter, ampoule method. From the power-times curves, the maximum power (Pmax) in the l0g phase, the growth rate constant (k), the generation times (tG), the time of the maximum power (fmax), the heat effects (Q1оg ) for log phase, and the total heat effect in 45 h (Gtotai) of В thuringiensis strains can be obtained. The results indicate that their power-times curves are different. The relationship between their metabolic power-times curves and character of bacteria metabolism, and thermokinetics and gene expression were analyzed and discussed. Thecharacter of the bacteria power-times curves reflected the physiologic character of gene expression. The microcalorimetric method proved to be a reliable and sensitive tool for the assessment of the growth metabolism, the heat output in bacteria and itsengineered strains. The determination of the thermokmetic character is beneficial to the control of fermentation.