Control of Soil Extracellular Enzyme Activities by Clay Minerals—Perspectives on Microbial Responses (original) (raw)
Related papers
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...
Biology and Fertility of Soils, 2019
To ascertain the role of extracellular enzymes in soil biochemical reactions, we followed the changes in catalytic activity of an exogenous β-glucosidase (GLU) enzyme after its adsorption on a synthetic model humic-clay complex, composed by a lignite humic acid coupled by Al bridges to a Ca-montmorillonite (HM), and on three sterilised soils (DS, ISC and IST) with different properties. Either HM or the selected soils enabled a stable GLU adsorption that induced a significant decrease of GLU activity. In the case of soils, both the largest GLU adsorption and reduction of catalytic activity was observed for the clayey and organic matter-rich ISC soil. When the GLU-soil adducts were subjected to wetting and drying (W/D) cycles for 3 and 6 weeks, the enzyme activity was further largely reduced after the first 3 weeks of W/D, while the decrease progressed more slowly during the following 3 weeks. This was attributed to the increasing modification of the enzyme conformational structure due to formation of dispersive and hydrogen bonds with the inorganic and organic components of HM and soils. Our results showed that an exogenous extracellular enzyme, such as GLU, is quantitatively immobilised on model and real soil aggregates, and that the catalytic activity is significantly and progressively reduced by soil physical-chemical changes, thereby implying that soil biochemical transformations are to be accounted more to intracellular than extracellular enzymes.
Soil microorganisms and enzyme activity at different levels of organic matter stability
Journal of soil science and plant nutrition
Soil biological activity has important implications for soil carbon (C) sequestration. However, very little is known about the environmental factors, particularly the effect of soil mineralogy on availability of C for soil microorganisms. In this study, we have investigated the influences of soil type (clay mineralogy) on C mineralization and its effects on biological activity at different levels of soil organic matter stability. Two soils an allophanic, derived from recent volcanic ash and a kaolinitic, resulting from metamorphic parent materials were physically fractioned in to light (LF, coarse sand 250-2000 µm), intermediate (IF, fine sand53-250 µm) and mineral (MF, silt and clay < 53 µm) fractions. Several biological and biochemical analyses at Ah horizons of mineral soil and physical fractions were conducted: soil respiration, enzymatic activities, carbohydrates and microbial biomass, amongst others soil variables. The results indicated that the bulk soil and physical fractions had a significant impact on cumulative C mineralized after 30 days of incubation and soil enzyme activities. More than 76% of total C-CO 2 variation was explained by stepwise multiple regression analysis including factors such as soil enzymes (β-glucosidase, dehydrogenase and phosphatase) and inorganic P. Soil ATP extraction was a good indicator of microbial activity, because of a positive and significant correlation among ATP and i) C-CO 2 and ii) metabolic quotient (soil respiration rate divided by microbial biomass). We also found an inverse and significant relationship between Al pyrophosphate (Al bound to SOM) and the C-CO 2 in volcanic soil, whereas the same correlation did not occur in kaolinitic soil. Our results confirmed a greater stabilization capacityof MF in allophanic than in kaolinitic soils due to the amorphous minerals clay materials.
Applied Soil Ecology, 2015
In a litter manipulation experiment in a temperate deciduous oak forest in Central Europe, we examined soil carbon contents and density fractions, as well as b-glucosidase and polyphenol oxidase enzyme activities, which play central roles in the degradation of litter and soil organic matter. Our measurements were taken in the DIRT (detritus input and removal treatments) plots, where manipulations include doubling of leaf litter or woody debris inputs, as well as removal of litter, trenching to prevent root inputs, and removal of all litter inputs. After 10 years of manipulation, soil C content did not vary predictably among plots, although the amount of light fraction material was greater in control and litter addition plots compared to litter removal plots. Even after 10 years of litter addition, there were no significant differences in activities of either enzyme in double litter plots compared to control plots, a result consistent with other observed measures of microbial activity. However, removal of roots and litter caused significant decreases in b-glucosidase activities very quickly, and these differences increased over time. However, polyphenol oxidase activities were not significant different among treatments. Enzyme activities were not correlated with total soil carbon contents, but activities of both enzymes were significantly and positively related to the amount of light fraction carbon, suggesting that enzymes respond to increases in labile carbon availability.
Soil Biology and Biochemistry, 2020
Mineralization of soil organic carbon and CO 2 emission from the soil is slowed by interactions between organic matter and minerals. The main minerals involved are clay minerals and oxides but there is limited understanding of their effects when combined, as occurs in soil. We aimed to determine the effects of clay content and composition on organic carbon stabilization in soil, and the mechanisms involved. This was achieved by studying the decomposition of alfalfa residues in artificial soils made from quartz sand and kaolinite with and without additions of the non-layered colloids (NLCs) goethite, manganese oxide or imogolite. The artificial soils were inoculated with microbes from natural soil and incubated at 23 • C in the dark at 60% of water holding capacity for 180 days. With increasing contents of clay and NLCs, organic carbon mineralization decreased, whereas carbohydrate and microbial biomass carbon contents increased. Of the NLCs, goethite had the least effect and imogolite the greatest effect on carbohydrate content. The effects of the treatments on mineralization and carbohydrate content were explained mostly by specific surface area (> 83% of variation), presumably due to the effects on sorption. The effects of the treatments on microbial biomass were related to the volume of habitat (water-filled pore space) and availability of substrate (influenced by sorption). These results showed that clay content and composition influenced the stabilization of soil organic carbon mostly through the supply of surfaces for sorption reactions rather than via interactions unique to particular colloids.
Soil enzyme activity in response to long-term organic matter manipulation
Soil Biology and Biochemistry, 2014
Soil moisture Soil pH SOM a b s t r a c t Enzymes are considered to be a key soil component catalysing important transformations related to decomposition and nutrient turnover, and their activity in soil can be used as a measure of soil health. As part of the Síkf} okút DIRT (Detritus Input and Removal Treatments) Project in a temperate deciduous forest in northern Hungary, we examined the extent to which enzyme activity in soil is influenced by both the quality and quantity of plant detrital inputs. DIRT treatments include doubling of leaf litter and woody debris inputs as well as removal of litter and trenching to prevent root inputs. Our objective was to examine seasonal dynamics of soil phosphatase and b-glucosidase activities and to determine the effects of detrital manipulations on these dynamics. We found that the litter additions did not affect enzyme activities, but removal of roots caused significant decreases in enzyme activities. We conclude that plant-induced changes to soil enzyme activities are driven primarily by readily available, labile carbon provided by root turnover and root exudation rather than by aboveground detrital inputs. However, these results could also have been affected by changes in soil chemistry with detrital input removal: after only 6 years of litter removal, soil cation content decreased and soils became more acidic, both of which could inhibit enzyme activity. The soil phosphatase and b-glucosidase enzymes measured showed similar seasonal dynamics. Both enzymes showed the highest activities in spring coincident with high soil moisture and, presumably, high root activity. The minimal response of soil enzyme activity to dramatic litter additions suggests a level of resilience in ecosystem function in this forest, and suggests that aboveground litter is not a significant source of labile carbon to microbes in the mineral soil.
Relationships Between Enzyme Activities and Microbial Growth and Activity Indices in Soil1
Soil Science Society of America Journal, 1983
Soil enzyme activities are often used as indices of microbial growth and activity in soils. Quantitative information concerning which soil enzymes most accurately reflect microbial growth and activity is lacking. Relationships between the activities of 11 soil enzymes and microbial respiration, biomass, viable plate counts, and soil properties were determined in surface samples of 10 diverse soils. Correlation analyses showed that alkaline phosphatase, amidase, a-glucosidase, and dehydrogenase activities were significantly (P < 0.01) related to microbial respiration as measured by CO 2 evolution in soils which had received glucose amendments. Phosphodiesterase, arylsulfatase, invertase, a-galactosidase, and catalase activities were correlated at the 5% level while acid phosphatase and urease activities were not significantly correlated to microbial respiration. There was no significant correlation between the 11 soil enzymes assayed and CO 2 evolution in the 10 unamended soils. Only phosphodiesterase and a-galactosidase activities were significantly (P < 0.05) related to microbial numbers obtained on some selective culture media. Alkaline phosphatase, amidase, and catalase were highly correlated (P < 0.01) with microbial biomass as determined by CO 2
Soil Enzymes – Valuable Indicators of Soil Fertility and Environmental Impacts
Bulletin UASVM Horticulture, 66(2)/2009
Soil enzymes are known since long time. A lot of older publications demonstrate the importance of exogenous soil enzymes for nutrient cycling in soils and the fertility of soils. The latter plays an extraordinary role in sustainable agriculture. Therefore indicators are needed which can be used for controlling. In our experiments with different organic amendments (green manure, straw and composts) used to improve and keep soil fertility different influences on soil enzymatic activities could be demonstrated. Fertility level was tried to characterize with - and -glucosidase, alkaline phosphatase, and urease activity. Generally could be proven that the different amendments have significant influence on the different enzymes in time and spatial distribution. Especially heavy metals in soil solution have a strong impact on soil enzyme activity. The variation of enzyme activity during time depends on the specific enzyme under consideration and the soil habitat. Activity follows also a strong gradient with soil depths. For comparative studies it is recommended to test only the upper soil layers up to a depth of 10 cm.
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...