Acute toxic effects of three pesticides on Pseudomonas putida monitored by microcalorimeter

Abstract

A series of calorimetric experiments were performed to investigate the toxic effects of beta-cypermethrin (BCP), bensulfuron-methyl (BSM) and prometryne (PM) on Pseudomonas putida (P. putida). The metabolic action of P. putida on the three pesticides was studied by obtaining power-time curves. The growth of P. putida was inhibited completely in each case when the concentrations of pesticides were up to 80 μ g mL^{− 1}. The relationships between the inhibitory ratio (k) and doses of contaminants were approximately linear for the three pesticides. The total heat dissipated per milliliter (Q _total) for the pesticides decreased during the course of the experiment. The OD₆₀₀ of P. putida growth in the absence and presence of pesticides was also obtained. The power-time curves of P. putida growth coincided with its turbidity curves. This elucidates that microcalorimetric method agrees well with the routine microbiological method. Among these three pesticides, BSM was found to be the most toxic with an IC ₅₀ of 19.24 μ g mL^{− 1} against P. putida. PM exhibited moderate virulence with an IC ₅₀ of 27.86 μ g mL^{− 1} and BCP had the lowest toxicity with an IC ₅₀ of 39.64 μ g mL^{− 1}.

Keywords:

• Microcalorimetry
• toxic effect
• beta-cypermethrin
• bensulfuron-methyl
• prometryne

Acknowledgments

This work was supported in part by grants from the Sino-Italian, Sino-German PPP Governmental International Scientific and Technological Cooperation Project (Annex No. 3, 20063139, respectively), National Natural Science Foundation of China (No. 40873060, No. 40673065), the Specialized Research Fund for the Doctoral Program of Higher Education (20060491508), the Key Project of Chinese Ministry of Education (107077), the Hubei Key International Cooperation Project (2006CA007) and the 111 Project (B08030).