Gianfreda L., Sannino F., Violante A. (1995) Pesticide effects on the activity of free, immobilized and soil invertase. Soil Biology & Biochemistry, 27, 1201-1208.
ABSTRACT The influence of four pesticides (atrazine, carbaryl, glyphosate and paraquat) on the catalytic behaviour of invertase, either free, immobilized on inorganic and organic soil colloids or in soils, was investigated. Invertase was immobilized on a clean clay (montmorillonite), an organic compound (tannic acid), and on synthetic organo-mineral [Al(OH)x-tannate and Al(OH)x-tannate-montmorillonite] complexes. Soils with different physico-chemical properties were utilized. The effects of pesticides on invertase performance depended not only on the nature of the pesticide but also on the “status” of the enzyme, i.e. if free, immobilized or in soil. Glyphosate and paraquat enhanced the activity of invertase either free or immobilized on montmorillonite and both pesticides behaved as mixed-type non-essential activators. Activity decreases were instead measured for the enzyme immobilized on organic and organo-mineral matrices. Contrasting results (increases, decreases and no effects) were detected for soil invertase. A general inhibition effect was exhibited by methanol on free, immobilized or soil invertase, but the extent of inhibition depended on the enzyme microenvironment. The addition of atrazine and carbaryl caused partial increases of free and immobilized invertase activity, whereas carbaryl further reduced enzymatic activity in some soils.
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ABSTRACT: Pesticides are extensively used in agriculture as a part of pest control strategies. Owing to their xenobiotics characteristics, pesticides may adversely affect the proliferation of beneficial soil microorganisms and their associated biotransformation in the soil. Inactivation of nitrogen‐fixing and phosphorus‐solubilizing microorganisms is observed in pesticide‐contaminated soils. Recent studies show that some pesticides disturb molecular interactions between plants and N‐fixing rhizobacteria and consequently inhibit the vital process of biological nitrogen fixation. Similarly, many studies show that pesticides reduce activities of soil enzymes that are key indicators of soil health. The applied pesticides may also influence many biochemical reactions such as mineralization of organic matter, nitrification, denitrification, ammonification, redox reactions, methanogenesis, etc. However, a few reports reveal some positive effects of applied pesticides on soil health. In this chapter, we attempt to analyze the impacts of pesticides on soil microbial communities, soil biochemical reactions, and soil enzymes.Advances in Agronomy 05/2009; 102(1):159-200. · 5.06 Impact Factor
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ABSTRACT: The heavy use of organophosphorus pesticides in northeastern China strongly affects the ecological functions and the quality of the soil environment. In this work, a 30-day soil incubation experiment was conducted to evaluate the potential of using soil available P and the activities of soil dehydrogenase and acid phosphatase as indicators of the application of methamidophos and glyphosate. Two kinds of unpolluted soils, phaiozem and burozem, were selected as the test soils. The higher application rate of organophosphorus pesticide to the two soils caused more release of PO4 which finally entered the soil available P pool, suggesting that soil available P is one of the effective chemical markers for biodegradation of organophosphorus pesticides. Methamidophos exhibited a significant inhibitory effect on the activity of soil dehydrogenase. The extent of enzyme inhibition was almost positively correlated with the insecticide concentration, and the enzyme activity was gradually restored after day 15. However, its effect on soil acid phosphatase activity (stimulation or inhibition) seemed to be indefinite, and varied with the application rate, soil type, and incubation time. In the case of glyphosate, soil acid phosphatase activity was depressed significantly and the depressing extent could be a function of herbicide concentration and incubation time, but soil dehydrogenase activity showed an irregular variation with the herbicide application rate and soil type. In general, dehydrogenase activity was a good biochemical indicator for the biodegradation of methamidophos, but for glyphosate biodegradation the indicator was acid phosphatase activity.Soil & Sediment Contamination - SOIL SEDIMENT CONTAM. 01/2011; 20(6):688-701.
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ABSTRACT: The stability and activity of phytases in the soil environment may be affected by their sorption on soil particle surfaces and by substrate availability with important consequences for P cycling and nutrient bioavailability. This work evaluated the interaction of phytases with goethite, haematite, kaolinite, montmorillonite and two oxisol clays and investigated how this interaction is affected when myo-inositol hexakisphosphate (InsP6) was sorbed on the mineral surfaces. phyA histidine acid phosphatases of fungal origin were used and their ability to release orthophosphate from the InsP6-saturated minerals was evaluated.The phytases showed a high affinity for the mineral surfaces, with a loss of enzyme activity generally being observed over 24 h (up to 95% of the initially added activity). The loss of phytase activity was dependent on the type of mineral, with kaolinite and montmorillonite showing the greatest effect. Retention of enzyme activity was higher with the two oxisol clays, suggesting that the heterogeneous nature of clay surfaces and the presence of endogenous organic matter may limit the inhibition caused by interaction with minerals.In the presence of mineral surfaces saturated with InsP6, the partitioning of enzyme activity between the solution and the solid phase was shifted more towards the solution phase, presumably due to the mineral surfaces being occupied by the substrate. However, phytases were not able to release any orthophosphate directly from InsP6-saturated goethite and haematite, and hydrolysed InsP6 that was desorbed from haematite. Conversely, in the case of kaolinite and of the oxisol clays, where desorption was limited, phytases appeared to be able to hydrolyse a small fraction of the InsP6 adsorbed on the surfaces. These findings suggest that the bioavailability of P from inositol phosphates is governed to a large extent by the mineral composition of soil and by competitive effects for sorption on reactive surfaces among inositol phosphates and phytases.Soil Biology and Biochemistry 01/2010; 42(3):491-498. · 4.41 Impact Factor