The Effect of Glyphosate on Feather-Degrading Bacteria

Schimmel/Conrades Science Center Atrium

Glyphosate, the active ingredient in Roundup®, is the most commonly used herbicide, applied to over 80 million acres across the United States both in the agricultural industry and home gardens. Studies indicate that glyphosate persists in ground water, surface water, the soil, and even rain (Scribner et al., 2007). Bacillus spp. are soil bacteria that can be picked up by ground-foraging birds. Some Bacillus spp. are known to degrade the keratin in plumage. During contact with soil, feather-degrading Bacillus spp. are potentially exposed to glyphosate. This study investigated the effect of contact with glyphosate on feather degradation. First, a Kirby-Bauer Test was performed to determine that a concentration of 8.4375g/L (the concentration of glyphosate that is originally sprayed when a 6oz/gal solution of Roundup® is made) inhibited the growth of feather-degrading bacteria. Then, to quantify feather degradation in the presence of 8.4375g/L of glyphosate, 40 test tubes were prepared as follows: feather and feather media; feather, media, and bacteria; feather, media, and glyphosate; feather, media, glyphosate, and bacteria. All variations were conducted in replicates of 10. Aliquots were taken from each test tube for six consecutive days, and the concentration of oligopeptides released as a result of the degradation of feather keratin was measured at 230 nm. Results indicate that glyphosate inhibited feather degradation by 96.5%. Glyphosate alone did not damage feathers. These data suggest that glyphosate may affect the interaction of Bacillus spp. in the avian plumage ecosystem.