Amidase activity in soils

dc.contributor.author Frankenberger, William
dc.contributor.department Agronomy
dc.date 2018-08-15T10:11:32.000
dc.date.accessioned 2020-07-02T05:56:07Z
dc.date.available 2020-07-02T05:56:07Z
dc.date.copyright Tue Jan 01 00:00:00 UTC 1980
dc.date.issued 1980
dc.description.abstract <p>Amidase (acylamide amidohydrolase, EC 3.5.1.4) was studied in soils becase its substrates, aliphatic amides, have potentials as synthetic N fertilizers. This enzyme catalyzes the hydrolysis of amides producing NH(,3) and their corresponding carboxylic acids. Amidase activity was detected in soils and a simple, sensitive, and precise method was developed for its assay. This method involves steam distillation of the NH(,4)('+) produced by amidase activity when soil is incubated with buffered (0.1 M THAM, pH 8.5) amide solution and toluene at 37(DEGREES)C;Studies of the kinetic parameters of the reaction catalyzed by amidase showed that, by using the Lineweaver-Burk plot, the K(,m) values of amidase in 8 soils, with formamide, acetamide, and propionamide as substrates, averaged 12.3, 4.6, and 14.5 mM, respectively. The temperature dependence of the rate constants conformed to the Arrhenius equation up to the point of enzyme inactivation (65(DEGREES)C). The activation energy values for soil amidase averaged 46.9, 50.0, and 26.5 kJ/mole using formamide, acetamide, and propionamide as substrates, respectively;Amidase activity in soils was found to be influenced by the methods of handling, storing, and pretreating the sample before the enzyme assay. The distribution of amidase activity in soil profiles decreased with sample depth. Statistical analyses showed that amidase activity was significantly correlated with urease activity (r = 0.73***), organic C (r = 0.74***), total N (r = 0.74***), and percentage clay (r = 0.69***) in 21 Iowa surface soils samples;Tests indicated that of the 21 trace elements studied, Ag(I), Hg(II), As(III), and Se(IV) were the most effective inhibitors of amidase ((GREATERTHEQ) 20% inhibition at 5 (mu)mole/g soil). The average inhibition of soil amidase by each of 16 pesticides added at the rate of 10 (mu)g/g of soil ranged from 2% with Dinitramine, Eradicane, and Merpan to 10% with Sutan;The transformations of N in 25 amides and their derivatives were studied and compared with those of N in (NH(,4))(,2)SO(,4) and urea added to field-moist soil samples and incubated under aerobic conditions at 30(DEGREES)C for 14 days. With the majority of the amides studied, the inorganic N produced accumulated as No(,3)('-). More than 40% of the amide-N was recovered as NH(,4)-N when thioacetamide, fluoroacetamide, and 2-chloroacetamide were added to soils. With one sandy soil, treatment of urea, formamide, N-benzylformamide, and p-nitrobenzamide showed accumulation of NO(,2)-N;Studies of the properties of amidase extracted from bacteria isolated from soils showed that it has lower values than soil amidase in the following properties: optimal pH (7.0 vs 8.5), optimal temperature (50 vs 60(DEGREES)C), K(,m) value (5.6 vs 12.3 mM), activation energy (18.9 vs 46.9 kJ/mole) and temperature coefficients (1.28 vs 1.75).</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/6722/
dc.identifier.articleid 7721
dc.identifier.contextkey 6278704
dc.identifier.doi https://doi.org/10.31274/rtd-180813-3549
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/6722
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/79521
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/6722/r_8106010.pdf|||Sat Jan 15 01:27:38 UTC 2022
dc.subject.disciplines Agricultural Science
dc.subject.disciplines Agriculture
dc.subject.disciplines Agronomy and Crop Sciences
dc.subject.keywords Agronomy
dc.subject.keywords Soil microbiology and biochemistry
dc.title Amidase activity in soils
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication fdd5c06c-bdbe-469c-a38e-51e664fece7a
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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