Fungal bioaugmentation of two rice husk-based biomixtures for the removal of carbofuran in on-farm biopurification systems

Abstract

The ligninolytic fungus Trametes versicolor was employed in the bioaugmentation of compost- (GCS) and peat-based (GTS) biomixtures for the removal of the insecticide-nematicide carbofuran (CFN). Among several lignocellulosic substrates, fungal colonization was best supported in rice husk, and this pre-colonized substrate was used to prepare the biomixtures. Estimated half-lives for CFN were 3.4 and 8.1 days in the GTS and GCS biomixtures, respectively. The CFN transformation products 3-hydroxycarbofuran and 3-ketocarbofuran were detected at the moment of CFN application, but their concentration continuously decreased to complete removal in both biomixtures. Mineralization of 14Cradiolabeled CFN was faster in GTS (k=0.00248 day−1) than in GCS (k=0.00188 day−1). Complete elimination of the toxicity in the matrices was demonstrated after 48 days. Overall data suggest that the bioaugmentation improved the performance of the GTS rather than the GCS biomixture.