Natural tolerance of cyanobacteria to the herbicide glyphosate

Abstract

SUMMARYSynechocystis PCC 6803 and Anabaena variabilis ATCC 29413 showed a high degree of tolerance to the herbicide glyphosate, applied as the free acid, the monoisopropylamine sait or the commercial formulation (Roundup''). Differential toxicity between herbicide formulations was observed (Roundup > isopropylamine salt > free acid) and correlated with their rates of uptake. There was no evidence of glyphosate degradation. Shikimate accumulation, together with partial alleviation of inhibition by aromatic amino acids, suggests that the target site for glyphosate is in the pathway of aromatic amino acid biosynthesis.

Herbicide Contamination of Freshwater Ecosystems: Impact on Microbial Communities

“…In the same way, the Cyanobacteria, which are photosynthetic prokaryotes, exhibited a wide range of EC 50 values varying from 2 to 1183 mg/L. However, despite this variability in EC 50 values, Cyanobacteria in general appear to be less sensitive to glyphosate than eukaryotic photosynthetic microorganisms (Powell et al, 1991). This tolerance of glyphosate could be explained by various mechanisms, notably the ability of Cyanobacteria to metabolize phosphonate (Forlani et al, 2008).…”

“…With the exception of Roundup, in which the surfactant is known to be polyethyloxylated tallowamine (POEA), information about the surfactants involved are generally not clearly stated by the manufacturers. Furthermore, several studies have shown that the surfactant molecules also make the commercial product (in particular, Roundup) more toxic than the technical grade compound (salt or free acid forms) (Powell et al, 1991;Diamond & Durkin, 1997;Giesy et al, 2000;Tsui & Chu, 2003).…”

Influence of bispyribac sodium on nitrogenase activity and growth of cyanobacteria isolated from paddy fields

“…O-X, the herbicide also inhibited nitrogenase activity by about 50% but the dry matter increased. Powell et al (1991) reported that nitrogenase activity was more sensitive to the isopropylamine salt of glyphosate than was photosynthetic O 2 evolution.…”

Glyphosate pathways to modern diseases VI: Prions, amyloidoses and autoimmune neurological diseases

“…The authors demonstrated that the shellfish were contaminated with BMAA, but also remarked that there was intensive chemical-based agriculture in the region [77]. Interestingly, cyanobacteria have been found to be remarkably resistant to glyphosate [78,79], and this could contribute to the recent record-setting algal blooms in the Great Lakes region, where glyphosate is extensively used on genetically modified (GM) RoundupReady crops [80].…”