Degradation of glyphosate and other pesticides by ligninolytic enzymes

Abstract

The ability of pure manganese peroxidase (MnP), laccase, lignin peroxidase (LiP) and horseradish peroxidase (HRP) to degrade the widely used herbicide glyphosate and other pesticides was studied in separate in vitro assays with addition of different mediators. Complete degradation of glyphosate was obtained with MnP, MnSO4 and Tween 80, with or without H2O2. In the presence of MnSO4, with or without H(2)O(2), MnP also transformed the herbicide, but to a lower rate. Laccase degraded glyphosate in the presence of (a) 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), (b) MnSO(4) and Tween 80 and (c) ABTS, MnSO4 and Tween 80. The metabolite AMPA was detected in all cases where degradation of glyphosate occurred and was not degraded. The LiP was tested alone or with MnSO4, Tween 80, veratryl alcohol or H2O2 and in the HRP assay the enzyme was added alone or with H2O2 in the reaction mixture. However, these enzymes did not degrade glyphosate. Further experiments using MnP together with MnSO4 and Tween 80 showed that the enzyme was also able to degrade glyphosate in its commercial formulation Roundup Bio. The same enzyme mixture was tested for degradation of 22 other pesticides and degradation products present in a mixture and all the compounds were transformed, with degradation percentages ranging between 20 and 100%. Our results highlight the potential of ligninolytic enzymes to degrade pesticides. Moreover, they suggest that the formation of AMPA, the main metabolite of glyphosate degradation found in soils, can be a result of the activity of lignin-degrading enzymes.

Microbial degradation of pesticide: A review

“…The biochemical reactions for degradation are achieved through a number of different enzymes such as dehydrogenases (Bourquin, 1977;Singh and Singh, 2005), cytochrome p450 (Castro et al, 1985;Jauregui et al, 2003), dioxigenases (Nadeau et al, 1994;Van Eerd et al, 2003), ligninases (Pizzul et al, 2009). Several reports have documented the capability of different genera of fungi to degrade organochlorines.…”

The Role of White-rot Fungi in Herbicide Transformation

“…It is well known that ABTS mediates the oxidation of non-phenolic compounds of lignin [80] and the presence of unsaturated fatty acids (Tween 80) improves the oxidation process catalyzed by Mn peroxidases and laccases due to the production of lipid peroxyl or alkoxyl radicals [81]. The hypothetical mechanism of bentazon degradation may be the following Mn peroxidase and laccase generated lipid peroxyl or alkoxyl radicals; in the presence of these radicals Mn peroxidase oxidizes Mn 2+ to Mn 3+ , which in turn oxidizes bentazon, whereas laccase uses ABTS as redox-mediator for bentazon oxidation.…”

Chlorpyrifos degradation in a Biomix: Effect of pre-incubation and water holding capacity

“…The ligninolytic enzyme activity (Table 4) and degradation of chlorpyrifos ( Figure 1a) at different pre-incubation times followed a similar behavior, obtaining both the highest values at 15 days of pre-incubation. In some works, ligninolytic activity has been correlated to the degradation of several pesticides, such as isoproturon (Castillo and Torstensson, 2007;Von Wirén-Lehr et al, 2001) and chlorpyrifos and TCP (Coppola et al, 2007;Pizzul et al, 2009). Considering that the highest chlorpyrifos degradation, the highest microbial respiration and the highest ligninolytic enzyme activity were when biomix was preincubated for 15 days, this pre-incubation time was chosen to evaluate the effect of the moisture content of the biomix in the pesticide degradation.…”