Polyacrylamide as a substrate for microbial amidase in culture and soil

Kay-Shoemake, Jeanine L. and Watwood, Mary E. and Sojka, Robert E. and Lentz, Rodrick D. (1998) Polyacrylamide as a substrate for microbial amidase in culture and soil. Soil Biology & Biochemistry. 30(13):1647-1654.

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Abstract

High molecular weight, linear polyacrylamide (PAM) with anionic charge is added to agricultural
soils as an anti-erosion additive. Research indicates that soil microorganisms are able to utilize
PAM as a source of N and that inorganic N pools are altered in some PAM-treated soils. The potential
role of hydrolytic amidase activity in the microbial utilization of PAM for N was investigated. Intracellular
and extracellular amidase activity was measured over time in enrichment cultures which used
PAM as sole N source. Enzyme activity increased concomitant with cell growth and N removal from
PAM. Cell growth, N removal and amidase production were dependent upon readily-available C in the
medium. Amidase activity and substrate specificity were determined for PAM-utilizing enrichment cultures
exposed to various N sources. Polyacrylamide-specific amidase activity appears to be inducible,
and not constitutive, based on the lack of amidase activity in cultures supplied with only ammonium
nitrate for N versus substantial activity when PAM was added as an amendment with or without ammonium
nitrate. Cultures amended with propionamide exhibited amidase activity largely specific for
this small amide substrate, while cultures supplied with PAM as sole N source exhibited amidase activity
specific for formamide, propionamide and PAM. Amidase activity and substrate specificity were
determined for PAM-treated and untreated agricultural field soils. Polyacrylamide-specific amidase activity
was higher in PAM-treated soil (14.86 ± 14.0 pg NH4 released soil) than in untreated soil
(1.02 ± 2.3 pg NH4 released C I soil); activity specific for low molecular weight amides was slightly
elevated or unchanged in PAM-treated soil as compared with untreated soil.

Item Type:	Article
NWISRL Publication Number:	0982
Subjects:	Polyacrylamide (PAM) > Water-soluble PAM (WSPAM) Soil > Chemistry Mass Import - autoclassified (may be erroneous)
Depositing User:	Users 6 not found.
Date Deposited:	20 Nov 2010 21:54
Last Modified:	17 Nov 2016 16:06
Item ID:	709
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/709