Response of ligninolytic macrofungi to the herbicide atrazine: dose-response bioassays

Abstract

The effect of atrazine concentrations on mycelial growth and ligninolytic enzyme activities of eight native ligninolytic macrofungi isolated in Veracruz, México, were evaluated in a semi-solid culture medium. Inhibition of mycelial growth and growth rates were significantly affected (p=0.05) by atrazine concentrations (468, 937, 1875, and 3750 mg/l). In accordance with the median effective concentration (EC50), Pleurotus sp. strain 1 proved to be the most tolerant isolate to atrazine (EC50=2281.0 mg/l), although its enzyme activity was not the highest. Pycnoporus sanguineus strain 2, Daedalea elegans and Trametes maxima showed high laccase activity (62.7, 31.9, 29.3 U mg/protein, respectively) without atrazine (control); however, this activity significantly increased (p<0.05) (to 191.1, 83.5 and 120.6 U mg/protein, respectively) owing to the effect of atrazine (937 mg/l) in the culture medium. Pleurotus sp. strain 2 and Cymatoderma elegans significantly increased (p<0.05) their manganese peroxidase (MnP) activities under atrazine stress at 468 mg/l. The isolates with high EC50 (Pleurotus sp. strain 1) and high enzymatic activity (P. sanguineus strain 2 and T. maxima) could be considered for future studies on atrazine mycodegradation. Furthermore, this study confirms that atrazine can increase laccase and MnP activities in ligninolytic macrofungi.

&lt;i&gt;In vitro&lt;/i&gt; Evaluation of Growth Inhibition of Some Common Soil Fungi by Selective and Non-selective Herbicides

“…However, on the other extreme, atrazine was the least potent of the herbicides to the point that it completely failed to arrest the mycelial growth of T. viride even at the highest concentration tested. This corroborate the findings of Rodriguez-Kahana et al [14], who had earlier reported that all the concentrations of atrazine tested, 8, 20, 40 and 80 ppm enhanced T. viride growth; and that of Cupul et al [13], who reported that although, atrazine inhibited the mycelial growth rate of all the tested macrofungi (Cymatadoderma elegans, Daedalea elegans, Pleurotus djamor, Pleurotus sp., Pycnoporus sanguineus and Trametes maxima), non reached 100% under the tested doses(468, 937, 1875 and 3750 mgL -1 )with some fungi not inhibited at all at lower doses, and concluded that moderate doses of atrazine are not toxicto the fungi. Variation in the degree of mycelial growth inhibition may be attributed to the differential toxicity of the herbicides arising from their chemical composition and the degradative capacity of the respective fungi.…”

“…To understand fungal capacity to colonize and settle on a particular substrate, it is important to study their growth rate [13]. Of all the herbicides employed in this study, 2,4-D appeared to be the most potent as it not only reduced the radial mycelial growth rate with increased concentration like the other herbicides, but resulted in a100% mycelial growth inhibition of all the fungi at 1% v/v.…”

Bioremediation of Endosulfan under Solid-State and Submerged Fermentation of Pleurotus ostreatus and its Correlation with Lignolytic Enzyme Activities

“…This can be concluded from results that lignolytic enzymes are tolerant to selected concentrations (55 mg kg -1 ) of Endosulfan. P. ostreatus is considered the most tolerant fungus to many pollutants [34] and the increase in Laccase and MnP activity during the incubation under SMF and SSF conditions due to Endosulfan spiking is in accordance with the earlier observations [34] that observed the higher activity of Laccase in the presence of atrazine than its associated control. This seems unusual because generally the addition of pollutants decreases lignolytic enzyme activities.…”

Biodegradation of atrazine and ligninolytic enzyme production by basidiomycete strains&nbsp;

“…Laccases (EC 1.10.3.2), lignin peroxidases (LiP; EC 1.11.1.14) and manganese peroxidases (MnP; EC 1.11.1.13) are responsible for the degradation of the most recalcitrant molecule in nature [8]. Thus, the co-metabolic biodegradation of pesticides, PAHs (polycyclic aromatic hydrocarbons), polychlorinated phenols, polymers, dioxins, pesticides, and dyes by ligninases have been subject of intense research [9,10,11,12,13].…”