Table 2.
Experimental conditions of studies that tested effects of glyphosate or formulated glyphosate on growth of rumen microbes or ruminal function
| Citation | Product tested1 | Culture system | Source of microbes | Concentrations in culture2 (range of non-zero amounts in mg/mL) |
Reported findings3 |
|---|---|---|---|---|---|
| Shehata et al. (2013) | Formulated (Roundup Ultra Max) | Batch culture | Single strain bacteria | 0.075–54 | MIC values ranged from 0.15 to 5 mg/mL |
| Krüger et al. (2013) | Formulated (Roundup Ultra Max) | Batch culture | Single strain bacteria | 0.1–10 | Results are artifact of confounding incubation times and glyphosate amounts. |
| Krüger et al. (2013) | N-(Phosphono-methyl) glycine | Batch culture | Single strain bacteria | 0.1–10 | Glyphosate or glyphosate formulations more toxic at large doses and extended incubations for E. faecalis and C. botulinum |
| Ackermann et al. (2015) | Glyphosate | Batch culture with rumen fluid | Rumen fluid | 0.001–0.1 | Differences in ciliate protozoa are presented but they do not appear meaningful. No differences were observed for any ciliates with high vs. low grain diets. |
| Hüther et al. (2005) | Formulated (Roundup Ultra) | Fistulated sheep rumen | Rumen fluid | 0.77 g/d a.i. Avg conc. = 0.07 mg/mL | None |
| Riede et al. (2016) | Formulated (Plantaclean 360) | Semicontinuous culture | Rumen fluid | 0.42–2.92 mg/d added. 0.0006 - 0.004 and 0.0003 - 0.003 mg/mL, initial and average. |
No adverse findings. |
| Nielsen et al. (2018) | Formulated (Glyfonova® 450 PLUS) | Batch culture | 5 – 80 | All bacteria had high MIC values. | |
| Nielsen et al. (2018) | Glyphosate, glyphosate salt, Glyfonova®, Roundup® | Batch culture | 0.04–0.16 of the active compound | Dose-dependent alleviation of the inhibitory effect of formulated glyphosate with aromatic amino acids. | |
| Nielsen et al. (2018) | water (CTR), glyphosate 2.5 mg/kg/day (GLY5), glyphosate 25 mg/kg/day (GLY50) or Glyfonova 25 mg/kg/day glyphosate acid equivalent (NOVA) by oral gavage | In vivo | 0.006–0.03 (in colon) | Glyphosate or formulated glyphosate administered at up to 50× the European ADI had limited effects on bacterial community composition in Sprague Dawley rats. | |
| Wicke et al. (2019) | Glyphosate | Batch culture | B. subtilis or E. coli | 0.1–1 | Glyphosate effects were reduced by amino acids in media and microbes adapt to grow in presence of glyphosate. |
1Roundup Ultra Max (Monsanto, St. Louis, MO); Plantaclean 360 (Plantan GmbH, Buchholz, Germany); Glyfonova 450 Plus (FMC Corporation).
2Values presented are targeted amounts added to media, unless otherwise noted, and all values are expressed as concentrations on an acid equivalent (a.e.) basis.
3Paper states that formulated glyphosate was used and presumably the amounts added to tubes are calculated based on glyphosate concentrations.
4Conclusions are those of the cited authors and not necessarily those of the authors of this manuscript.