This new study published in the Brazilian Journal of Microbiology indicates that the world’s most widely used herbicide - glyphosate - may be contributing to the enhanced growth of the pathogenic bacteria P. aeruginosa in our environment.

Influence of glyphosate in planktonic and biofilm growth of Pseudomonas aeruginosa

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4204984/

Authors: Ilana Schneider Lima, Nicole Carmo Baumeier, Rosimeire Takaki Rosa,2 Patrícia Maria Stuelp Campelo, Edvaldo Antonio Ribeiro Rosa

Abstract

This study evaluated the impact of different concentrations of glyphosate (Rondup®) on planktonic and biofilm growth of P. aeruginosa. Aerobic and anaerobic cultures of P. aeruginosa ATCC®15442 inoculated in MHB + glyphosate (0.845 ppm, 1.690 ppm, 8.45 ppm, 16.90 ppm, 84.50 ppm, 169 ppm, 845 ppm, and 1690 ppm) and cultured in normoxia and anoxia, following their OD560nm every hour for 24 h. Biofilms of adapted cells were formed in the presence of glyphosate (0.845 to 1690 ppm) in normoxia and anoxia for 36 h. Glyphosate at concentrations higher than 84.5 ppm reduces the cell density of planktonic aerobic cultures (p < 0.05). However, these same concentrations favor the planktonic anaerobic growth (p < 0.05). On the other hand, the herbicide favors a slight growth of biofilms in a concentration-dependent manner up to 84.5 ppm (p > 0.05), and more pronounced over 169 ppm. Anaerobic biofilms have their growth more readily favored (p < 0.05), regardless of concentration. In a concentration-dependent manner, glyphosate interferes with the growth ability of P. aeruginosa ATCC®15442.