Biotransformation of the Insecticide Lindane by the White Rot Basidiomycete Phanerochaete chrysosporium

Abstract

Biotransformation of the insecticide lindane by the white rot basidiomycete Phanerochaete chrysosporium has been investigated in liquid cultures. Some polar metabolites and carbon dioxide were produced from the pesticide. Among the metabolites identified were tetrachlorocyclohexene, tetrachlorocyclohexene epoxide and tetrachlorocyclohexenol. When used as a substrate, tetrachlorocyclohexene was also converted by the fungus to tetrachlorocyclohexenol, polar metabolites and carbon dioxide. Three incubation conditions leading to low and high peroxidase production were assayed. Data from these experiments, as well as in-vitro incubations with purified enzymes, ruled out any involvement of the peroxidases in lindane biotransformation and mineralization. Moreover, 1-aminobenzotriazole (a P450 inactivator) drastically reduced pesticide metabolism. Conversely, phenobarbital (a P450 inducer) did not significantly increase lindane breakdown.

New aspects on atrazine biodegradation

“…Degradation of atrazine by the white-rot fungus Phanerochaete chrysosporium was demonstrated by a 48% decrease of the initial herbicide concentration in the growth medium within the first 4 days of incubation. Results point out 25% mineralization of the ethyl group of the herbicide and the formation of hydroxylated and/or Ndealkylated metabolites; however, no mineralization of ring-14C-labeled atrazine was observed (Mougin et al, 1994). In non-sterile soil samples amended with the same white-rot fungus in the presence of wood chips, atrazine was mineralized especially in summer, spring and fall (Entry et al, 1996).…”

Degradação e formação de resíduos não-extraíveis ou ligados do herbicida atrazina em solo

“…Portanto, praticamente não houve mineralização da atrazina em meio de cultura, independentemente do inóculo, embora haja relatos de sua ocorrência (Mougin et al, 1994;Radosevich et al, 1995). Comparando-se a mineralização de atrazina em solo e em meio de cultura, observou-se que ela ocorreu de forma significativa somente no solo natural, e não ocorreu no meio de cultura com inóculo de solo ou de P. putida.…”

“…A despeito da sua aparente degradabilidade, e devido ao seu uso extensivo, há relatos de contaminação de ecossistemas terrestres com atrazina, que pôde ser encontrada tanto em águas superficiais como de profundidade, em muitos países (Mougin et al, 1994).…”

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“…Other researchers reported microbial associations (Assaf and Turco, 1994;de Souza et al, 1998a;de Souza et al, 1998b;Ghosh and Philip, 2004;Smith et al, 2005) and fungal species (Donnelly et al, 1993) which mineralized atrazine. White-rot fungus Phanerochaete chrysosporium degraded a 48% atrazine within four days (Mougin et al, 1994). Another lignocellulolytic fungus Pleurotuspulm onarius was reported mainly ecological studies, bacterial diversity can be explored with the help of molecular techniques like denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE).…”