Microcalorimetric Studies on Influence of Sm^3＋, Dy^3＋ on Growth and Sporulation of Bacillus thuringiensis

By using an LKB-2277 Bioactivity Monitor and cycle-flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry Ⅱ strain at 28 ℃ have been obtained. The metabolic thermogenic curves of Bt cry Ⅱ contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corresponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm^3 , Dy^3 ions, the thermokinetic parameters such as the growth rate constants k. the interval time τ1, the maximum power PMAX1 and heat-output QLOG for log phase, the maximum power PMAX2 and heat-output QSTAT for stationary phase, the heat-output QSPOR for sporulation phase and total heat effects QT were calculated. Sm^3 and Dy^3 ions have promoting action on the growth of Bt cryⅡ in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range, It has also been found that the effects of Sm^3 and Dy^3 ions on Bt during the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare-earth elements in the environmental ecosystem.

Microcalorimetric Studies on Influence of Sm~(3+), Dy~(3+) on Growth and Sporulation of Bacillus thuringiensis

By using an LKB‐2277 Bioactivity Monitor and cycle‐flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry II strain at 28 °C have been obtained. The metabolic thermogenic curves of Bt cry II contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corresponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm³⁺, Dy³⁺ ions, the thermokinetic parameters such as the growth rate constants k, the interval time τ_I, the maximum power P_MAX1 and heat‐output Q_LOG for log phase, the maximum power P_MAX2 and heat‐output Q_STAT for stationary phase, the heat‐output Q_SPOR for sporulation phase and total heat effects Q_T were calculated. Sm³⁺ and Dy³⁺ ions have promoting action on the growth of Bt cry II in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range. It has also been found that the effects of Sm³⁺ and Dy³⁺ ions on Br firing the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare‐earth elements in the environmental ecosystem.