Biodegradation of Aged Residues of Atrazine and Alachlor in a Mix-Load Site Soil by Fungal Enzymes

Abstract

Soils from bulk pesticide mixing and loading (mix-load) sites are often contaminated with a complex mixture of pesticides, herbicides, and other organic compounds used in pesticide formulations that limits the success of remediation efforts. Therefore, there is a need to find remediation strategies that can successfully clean up these mix-load site soils. This paper examined the degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT) and alachlor (2-chloro-2 , 6 -diethyl-N-[methoxymethyl]-acetanilide) in contaminated mix-load site soil utilizing an extracellular fungal enzyme solution derived from the white rot fungus, Phanerochaete chrysosporium, grown in a packed bed bioreactor. Thirty-two percent of AT and 54% of AL were transformed in the biometers. The pseudo first-order rate constant for AT and AL biodegradation was 0.0882 d −1 and 0.2504 d −1 , respectively. The half-life (t 1/2 ) for AT and AL was 8.0 and 3.0 days, respectively. Compared to AT, the initial disappearance of AL proceeded at a faster rate and resulted in a greater amount of AL transformed. Based on the net Co 2 evolved from the biometers, about 4% of the AT and AL initially present in the soil was completely mineralized.

Ametryn removal by Metarhizium brunneum: Biodegradation pathway proposal and metabolic background revealed

“…Complete mineralization is the most favorable way of biodegradation; however, the vast majority of the xenobiotics biodegradation pathways (including triazines) end in the formation of by-products. Formation of ametryn metabolites during the experiments presented in this work is partially in agreement with the reactions of atrazine biodegradation, where the formation 2-hydroxyatrazine has been observed in many species (Atrazine Pathway Map, 2017; KEGG Atrazine degradation -Reference pathway, 2017; Govantes et al, 2009;Solomon et al, 2013;Abigail et al, 2013), while deethylation of ethanamine substituents seems to be characteristic for fungal strains and mammals (Chirnside et al, 2011;Pereira et al, 2013, Sciali et al, 2014. Figure 6.…”

Biodegradation of alachlor in liquid and soil cultures under variable carbon and nitrogen sources by bacterial consortium isolated from corn field soil

“…Past studies showed that the presence of additional substrates could initiate cometabolism of the desired compounds [15]. Bacteria and fungi can degrade alachlor through cometabolism [20,23,30]. …”

“…Thirty-two percent of atrazine and 54% of alachlor were degraded in the biometers using white rot fungus, Phanerochaete chrysosporium . The half-life for atrazine and alachlor was 8.0 and 3.0 days, respectively [23]. Ninety-nine percent of alachlor degradation was achieved in anoxic slurries of corn-cultivated soil due to the preexistence of microorganisms in the soil [24].…”

Bioremediation Potential of White Rot Fungi, Pleurotus Spp against Organochlorines

“…Most developed countries stopped using these pesticides after imposition of ban but developing or underdeveloped countries could not due to lack of policy [3]. White rot fungi (Basidiomycetes:Xylariaceae) are popular among all fungi as these can tolerate high concentration of pesticides from mix-load sites [4]. Several isolates of white rot fungi have been used since 1985 for biodegradation of OCPs.…”