Microcalorimetric study of the biological effects of Zn2+ on Bacillus thuringiensis growth

A microcalorimetric technique was used to investigate the influence of Zn2+ on the growth metabolism of Bacillus thuringiensis. LKB-2277 Bioactivity Monitor was employed to obtain the power-time curves, from winch the maximum peak-heat output power (P-max) in the log phase, the growth rate constants (k), the inhibitory ratios (I), the generational time (t(G)) and the total heat effect (Q(total)) in 23 It for the growth metabolism of Bacillus thuringiensis at 28 degreesC can be evaluated. The results indicate that the concentration of Zn2+ affects its growth obviously. Low concentration (0-50 mug/mL) of Zn2+ promotes the growth of Bacillus thuringiensis while high Concentration (50-500 mug/mL) of Zn2+ inhibits its growth. When the concentration reached up to 600 mug/mL, it can not grow at all.