Soil amidase activity in polyacrylamide-treated soils and potential activity toward common amide-containing pesticides

Abstract

Polyacrylamide (PAM) is currently used as an irrigation water additive to significantly reduce the amount of soil erosion that occurs during furrow irrigation of crops. Elevated soil amidase activity specific toward the large PAM polymer has been reported in PAM-treated field soils; the substrate specificity of the induced amidase is uncertain. PAM-treated and untreated soils were assayed for their capacity to hydrolyze the amide bond in carbaryl (Sevin), diphenamid (Dymid), and naphthalene acetamide. Based on results obtained with a soil amidase assay, there was no difference between PAM-treated and untreated soils with respect to the rate of amide bond hydrolysis of any of the agrochemicals tested. It appears that under these assay conditions the PAM-induced soil amidase is not active toward the amide bonds within these molecules. However, carbaryl was hydrolyzed by a different soil amidase. To our knowledge, this is the first soil enzyme assay-based demonstration of the hydrolysis of carbaryl by a soil amidase.

The influence of high application rates of polyacrylamide on microbial metabolic potential in an agricultural soil

“…PAM-specific amidase activity has been documented in laboratory cultures, as well as in field soil samples, following exposure to PAM (Kay-Shoemake et al, 1998b). The enzyme appears to have a broad substrate range, exhibiting activity against formamide and propionamide, but does not impact degradation rates of carbaryl, diphenamid or naphthalene acetamide in PAM-treated soils (Kay-Shoemake et al, 2000a). Intracellular and extracellular activity have been noted, and production and secretion of the enzyme appears to be dependent on C availability, as cells cannot derive C directly from PAM.…”

Polyacrylamide in Agriculture and Environmental Land Management

“…Nitrification of added urea appeared somewhat accelerated (approximately 10% over 2 weeks) in PAM-treated microcosm soils (Kay-Shoemake et al, 2000b), but no other significant impacts of PAM application on fertilizer fate were noted. Sorptive dynamics of the common pesticides, 2,4-D and atrazine, were not dramatically altered by PAM treatment of field soil samples, but some slight changes in desorption and degradation rates were reported (Watwood and Kay-Shoemake, 2000).…”

Polyacrylamide preparations for protection of water quality threatened by agricultural runoff contaminants

“…PAM-specific amidase activity has been documented in laboratory cultures, as well as in field soil samples, following exposure to PAM (Kay-Shoemake et al, 1998b) The enzyme appears to have a broad substrate range, exhibiting activity against formamide and propionamide, but does not dramatically impact degradation rates of carbaryl, diphenamid or naphthalene acetamide in PAM-treated soils (Kay-Shoemake et al, 2000a). Both intracellular and extracellular activity have been noted, and production and secretion of the enzyme appears to be dependent on C availability, as cells cannot derive C directly from PAM.…”