Growth response of microbial population exposed to synthetic pyrethroids

Growth curve experiment of various microorganisms was studied with different Synthetic Pyrethroids (Cypermethrin, Deltamethrin, Fenvalerate and Alpha Cyhalothrin). Cypermethrin showed drastic inhibitory effect on the growth of Pseudomonas (75%) and slight inhibition on Serratia (25%) and Bacillus (25%) while did not cause any appreciable change in Rhizobium and Azotobacter growth. Fenvalerate inhibited the growth of all microorganisms drastically (upto 50%) except Bacillus in which significant increase (25%) was observed. Deltamethrin inhibited the growth of Serratia, Azotobacter and Rhizobium (all up to 25%) but did not affect the population of Bacillus and Pseudomonas. Alpha cyhalothrin showed no significant effect on the growth of any microorganisms. All the synthetic pyrethroids has acted as stimulator for the population growth of Saccharomyces cereviseiae but consistently inhibited the growth of algae Spirullina and Phormidium sp and the growth of fungi Trichoderma and Phanaerochaete.