Reduced catalytic activity of an exogenous extracellular β-D-glucosidase due to adsorption on a model humic-clay complex and different soils under wetting and drying cycles (original) (raw)

Control of Soil Extracellular Enzyme Activities by Clay Minerals—Perspectives on Microbial Responses

Soil Systems

Knowledge of how interactions of clay minerals and extracellular enzymes (EEs) influence organic matter turnover in soils are still under discussion. We studied the effect of different montmorillonite contents on EE activities, using two experiments—(1) an adsorption experiment with a commercially available enzyme (α-glucosidase) and (2) an incubation experiment (10 days) where microorganisms were stimulated to produce enzymes through organic carbon (OC) addition (starch and cellulose). Soil mixtures with different montmorillonite contents were created in four levels to a sandy soil: +0% (control), +0.1%, +1%, and +10%. The potential enzyme activity (pEA) of four enzymes, α-glucosidase, β-glucosidase, cellobiohydrolase, and aminopeptidase, involved in the soil carbon and nitrogen cycle were analysed. The adsorption experiment revealed a reduction in the catalytic activity of α-glucosidase by up to 76% with increasing montmorillonite contents. However, the incubation experiment showe...

Persistent Activities of Extracellular Enzymes Adsorbed to Soil Minerals

Microorganisms, 2020

Adsorption of extracellular enzymes to soil minerals is assumed to protect them against degradation, while modifying their activities at the same time. However, the persistence of the activity of adsorbed enzymes remains poorly understood. Therefore, we studied the persistence of cellulase and α-amylase activities after adsorption to soil amended with various amounts (+1, +5, and +10 wt.%) of three typical soil minerals, montmorillonite, kaolinite, and goethite. Soil without mineral addition (pure soil), pure minerals, and pure dissolved enzymes were used as references. Soil mineral–enzyme complexes were prepared and then incubated for 100 days; temporal changes in enzyme activities were analyzed after 0, 0.1, 1, 10, and 100 days. The specific enzyme activities (activities normalized to protein content) and their persistence (activities relative to activities at day 0) were compared to enzyme activities in solution and after sorption to the control soil. Amylase adsorption to pure m...

How enzymes are adsorbed on soil solid phase and factors limiting its activity: A Review

International Agrophysics

A majority of biochemical reactions are often catalysed by different types of enzymes. Adsorption of the enzyme is an imperative phenomenon, which protects it from physical or chemical degradation resulting in enzyme reserve in soil. This article summarizes some of the key results from previous studies and provides information about how enzymes are adsorbed on the surface of the soil solid phase and how different factors affect enzymatic activity in soil. Many studies have been done separately on the soil enzymatic activity and adsorption of enzymes on solid surfaces. However, only a few studies discuss enzyme adsorption on soil perspective; hence, we attempted to facilitate the process of enzyme adsorption specifically on soil surfaces. This review is remarkably unmatched, as we have thoroughly reviewed the relevant publications related to protein adsorption and enzymatic activity. Also, the article focuses on two important aspects, adsorption of enzymes and factors limiting the ac...

Interpretation of the pH dependence of protein adsorption on clay mineral surfaces and its relevance to the understanding of extracellular enzyme activity in soil

Colloids and Surfaces A-physicochemical and Engineering Aspects, 1993

The pH dependence of the adsorption of bovine serum albumin (BSA) and Aspergihs niger fl-D-glucosidase on montmorillonite and of its structural consequences was studied by several methods in order to understand the mechanisms of interaction between extracellular enzymes and clay minerals in soils. The relative influence of electrostatic and hydrophobic interactions on adsorption was deduced from experiments involving the coadsorption of BSA and methylated BSA. Also, the surface coverage of the clay by the BSA was studied by following the release of a paramagnetic charge-compensating cation on adsorption of the protein. This method is based on the line broadening effect of the released cation on the 3'P NMR signal from phosphate in the solution, and the specific interfacial area of the BSA was deduced from the ratio of the surface covered by the quantity of protein adsorbed. Information on the secondary and overall structure of adsorbed BSA was obtained by Fourier transform IR spectroscopy from the frequency range and line width of the amide I/I' signal and from the intensity of the COOH band. Finally, the catalytic activity of the fi-u-glucosidase adsorbed on the clay was compared with its activity in solution, and the pH dependence of the adsorption was measured. The following general conclusions could be drawn from these experiments. (i) Below the isoelectric point (IEPI, proteins unfold on the clay surfaces in response to electrostatic attractive interactions, a phenomenon which inhibits enzyme activity. (ii) Near the IEP proteins are adsorbed with little modification of conformation and thus enzymes preserve their catalytic activities. (iii) Above the IEP the proportion of adsorbed proteins decreases due to electrostatic repulsive interactions, permitting the diffusion of enzymes in the liquid-filled pore network of the soil.

Efficiency of three buffers for extracting β-glucosidase enzyme in different soil orders: Evaluating the role of soil organic matter

Scientia Agropecuaria

The objective of this research was to evaluate extraction methods for β-glucosidases comparing three buffer solutions (MUB, acetate, and maleate) at different incubation times (0.5 h to 10 h) and in three different soil orders (Mollisols, Andisols and Ultisols). Seven acidic soils were evaluated, showing differences in pH, OM, and clay contents. To evaluate the effect of OM as enzymes source, one soil of each order was treated to partially remove its OM and then the enzyme assay was performed. When using MUB and maleate buffers the highest (32 and 31 µg-pNP g-soil-1 h-1 in average, respectively) were found, and the latter was significantly (p < 0.050) correlated with the soil clay content. The activity obtained with acetate buffer was much lower (38.2 µg-pNP g-soil-1 h-1 in average). The use of MUB buffer with 1 h of incubation is suggested as extraction method, showing good reproducibility and allowing to express higher enzyme potential for soil comparisons. For the Andisol and Ultisol, the enzyme activity significantly decreased with the OM removal (%) indicating that OM is the major source of the measured β-glucosidase activity, while a different trend was observed for the Mollisol, in which the mineral fraction (mainly 2:1 type clay) appears to be involved in the increased enzyme activity displayed after the initial OM removal.

Biochemically active humic substances in contrasting agricultural managements

Spanish Journal of Agricultural Research, 2016

ing (IEF) on the basis of the isoelectric point of the humic substances. IEF did not modify either the enzyme activity or the molecular structure of the complexes (Benítez et al., 2000; Ceccanti et al., 2008). Beta-glucosidase activity has been proposed as a good indicator for soil functions because its critical role on soil-carbon cycle (Nannipieri et al., 2012). The importance of extracellular β-glucosidase lies in the capacity of the soil to hydrolyse C substrates too large or insoluble for direct absorption by microbial cells. The characterization of stable humic-β-glucosidase compounds could assess the ability to fulfil essential Short communication oPEn accESS

Influence of biochar on potential enzyme activities in two calcareous soils of contrasting texture

A B S T R A C T Application of pyrolysed feedstocks or biochar has the potential to affect soil enzyme activity and function. Nevertheless, our detailed understanding of the mechanisms responsible for biochar-enzyme interaction is limited in arid soils. The main aim of this study was to study how the potential activity of several extra-and intra-cellular enzymes involved in C and N cycling, and microbial metabolism would respond to addition of biochar in two calcareous soils with fine and coarse texture. Three corn stalk biochars were prepared at 200, 400 and 600 °C and added to sandy and clayey soils at 0.5 and 1% (w/w). Soils with uncharred feedstocks; and without biochar and feedstock additions as the control treatment were also included in the experiment. The potential activities of soil enzymes were assayed. Compared with the control, addition of uncharred and charred feedstocks significantly stimulated the activities of catalase (1.3-to 4.3-fold), dehydrogenase (1.2-to 3.1-fold), cellulase (1.1-to 1.7-fold), invertase (1.3-to 5.8-fold) and protease (1.03-to 2.9-fold), which varied with pyrolysis temperature and addition rate as well as soil texture. The positive effects of biochar addition on soil enzymes were much greater at 1% than 0.5% application rates for all the assayed enzymes and in sandy than clayey soils for catalase, dehydrogenase and invertase. The change in enzyme activity with biochar addition primarily attributed to the change in soil microbial biomass. However, enzyme activities were lower in the soils amended with charred than uncharred biomass, and decreased as pyrolysis temperature increased. Our results showed clearly that uncharred feedstock and lower temperature biochars gave higher benefits to both contrasting textured soils than higher temperature biochars, largely connected to changes in the physiochemical properties of biochars. Nevertheless; long-term field experiments are required to verify whether the beneficial effect of uncharred vs. charred feedstocks would be maintained over long timescales under the conditions of this study. We conclude that although biochar application may improve enzyme activities of calcareous soils with low organic matter content, increasing pyrolysis temperature adversely affects soil enzymatic functions, depending mainly on soil texture and application rate. The study evidently indicates that corn biochar addition to arid-soils may have a high potential for improving the enzyme activities as important indicators of soil quality, and subsequently carbon sequestration and biogeochemical cycles.

Effect of Soils on the Behavior of Immobilized Enzymes

Soil Science Society of America Journal, 1994

The use of immobilized enzymes, such as oxidoreductases and hydrolases, in contaminated soils offers a simple, efficient, and inexpensive method for solving pollution problems in the soil environment. Investigations on the behavior of a laccase (from the fungus Trametes versicolor), a peroxidase (from horseradish [Armoracia rusticana P. Gaertner, Meyer & Scherb.]), and an acid phosphatase (from wheat [ Triticum aestivum L.] germ) were conducted in the presence of sand, various soils, and soil-sand mixtures. The enzymes were either free or immobilized on three natural supports (a montmorillonite, a kaolinite, and a silt loam soil). On immobilization, laccase and peroxidase retained high activities, whereas immobilized acid phosphatase showed reduced activity. The affinity of laccase and peroxidase for their substrates remained practically unchanged (similar Michaelis constant [K m ] values) and higher K m values (low substrate affinity) were obtained for immobilized acid phosphatase. By increasing the amount of soil in the soil-sand mixtures or the content of organic matter in soil, an inhibitory effect on the activity of free and immobilized enzymes was observed. The reusability of immobilized laccase and peroxidase, both in the absence and presence of soil, was evaluated by repeated incubation cycles with 2,4-dichlorophenol. After several incubation cycles, the immobilized enzymes retained different activity levels. Furthermore, in the presence of soils, the inhibitory effect decreased after each incubation cycle, indicating that the observed inhibition was, at least in part, due to soluble soil components easily extracted with the buffered substrate solution. Our results indicate that immobilized enzymes introduced into the soil environment have catalytic activity, but their performance is affected by organic or inorganic soil constituents.