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Enzymatic Activities in Coniferous Leaf Litter
Author(s) -
Spalding Brian P.
Publication year - 1980
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1980.03615995004400040021x
Subject(s) - cellulase , xylanase , chemistry , litter , carbohydrase , amylase , invertase , protease , food science , plant litter , botany , enzyme , biochemistry , biology , nutrient , agronomy , organic chemistry
Assays for measuring the activities of cellulase, xylanase, mannase, amylase, β‐glucosidase, invertase, and protease employing buffered suspensions of ground coniferous and deciduous leaf litter exhibited zero‐order kinetics. Only a small percentage of the whole‐litter activities of invertase (3%), β‐glucosidase (3%), and protease (1%) were extractable into 0.05 M potassium acetate, pH 5.0; however, extractable activities of cellulase and xylanase represented from 39 to 174% of the whole‐litter activities indicating their soluble exocellular nature. Extractable protease and amylase activities were best correlated ( r =0.65 and 0.65, respectively) with the average daily rates of CO 2 evolution in a group of 90 leaf litter samples equally representing 18 coniferous species. Enzymatic activities were readily detectable in extracts of all samples but classification of the samples by species provided little differentiation in the distribution of either enzymatic activities or rates of CO 2 evolution. Mannase, cellulase, and xylanase activities were well‐correlated with each other ( r =0.88) in all samples. Assays at‐tempting to measure a pool of readily‐metabolizable substances in litter by extractable reducing substances, ninhydrin‐positive substances, glucose, and phenolics failed to show correlation coefficients > 0.41 with rates of CO 2 evolution. Addition of D‐(+)‐catechin to litter extracts, up to levels equivalent to those observed in the group of samples, did not inhibit any carbohydrase thus suggesting the lack of inhibition of litter‐decomposing enzymes by the concentrations of phenolics present in these coniferous leaf litters.