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The nightmarish toxicological profile of Roundup herbicide (glyphosate) continues to emerge within the peer-reviewed research, this time revealing its role in supporting the growth of a pathogenic bacteria of great medical significance.
A concerning new study published in the Brazilian Journal of Microbiology titled, "Influence of glyphosate in planktonic and biofilm growth of Pseudomonas aeruginosa," indicates that the world's most widely used herbicide Roundup (glyphosate) may be contributing to the enhanced growth of the pathogenic bacteria P. aeruginosa in our environment.
The Brazilian team responsible for the study expressed concern over the "virtual nonexistence" of research evaluating glyphosate herbicide-pathogenic microbiota interactions, and conducted a series of microbial experiments to fill this data gap. They noted:
"Glyphosate is probably the herbicide most discharged into the environment. Due to its extensive use in the protection of crops, it is inevitable that it will reach surface and deep waters (Pournaras et al., 2007), especially after rainfalls."
P. aeruginosa is commonly found in watercourses and reservoirs in both oxygen (aerobic) and non-oxygen preferring forms (anaerobic), and can be a source of waterborne infection.
The results of the new study indicate that when exposed to varying concentrations of both glyphosate (a common contaminant found in GM agricultural runoff) and oxygen, both the aerobic the anaerobic and biofilm forming strains of this bacteria can thrive:
"Aerobic planktonic growth was superior to anaerobic one. This points to the possibility of P. aeruginosa, although a facultative organism (Davies et al., 1989; Yoon et al., 2002), has its growth significantly favored by the presence of molecular oxygen. Continuous bacterial exposure to low concentrations of glyphosate leads to increased rates of aerobic growth, which is somehow in agreement with previously published findings (Fitzgibbon and Braymer, 1988). By the contrary, in conditions of inaccessibility of molecular oxygen, the bacterium started to grow better in a concentration-dependent manner. It is possible that this phenomenon results from the use of the molecule as a source of phosphorus, as previously reported for the genus Pseudomonas (Peñaloza-Vazquez et al., 1995; Moore et al., 1983; Talbot et al., 1984). Glyphosate could also serve as a carbon source, which would be processed by both aerobic and anaerobic metabolisms (Rueppel et al., 1977), with increased rates in presence of oxygen. To support such theory, it has been found that different bacterial genera may promote catalysis of glyphosate using C-P lyases (van Eerd et al., 2003). Once broken up this connection, Pseudomonas spp. can produce glycine (Kishore and Jacob, 1987), which can also enhance growth."
The researchers also focused on the ability of glyphosate to support the growth of so-called biofilms, a closely adhering colony of bacteria embedded in a self-produced matrix of a "slimy" extracellular polymeric substance (EPS), revealing: