Use of actinobacteria consortia to improve methoxychlor bioremediation in diffrentmatrices

Abstract

Methoxychlor (MTX) is an organochlorine pesticide which has been banned in most countries; however it is still being used on agricultural products and against mosquito. This pesticide has estrogenic activity and mimics endocrine hormone functions. Thus, it results important to analyze its behavior in different matrices. Actinobacteria present the ability to degrade this pesticide, and its use in mixed cultures for bioremediation purposes can be advantageous. Streptomyces spp. A3, A6, A12, A14, M7 and S. coelicolor A3 (2) were used as defined mixed cultures for MTX removal, after checking the absence of antagonistic effects among them. The consortium consisting of Streptomyces spp. A6, A12, A14 and M7 was selected. This defined mixed culture was able to grow in slurry bioreactors with or without stimulation, in the presence of MTX and also to remove it from stimulated and non-stimulated bioreactors. An increase about 10% in MTX removal was observed in stimulated slurry bioreactors. MTX removal in soil was 56.4%. Maximum microbial growth and the absence of stationary growth phase were both observed in soil when the consortium was grown in the presence of MTX, while the opposite was observed in soil without MTX. When comparing soil and slurries, similar removal percentages values can be observed but at a time almost three times higher in soil. Indeed, when analyzing ex situ bioremediation by slurries bioreactors, reduced processing times can be achieved, compared to in situ bioremediation. However, it is important to analyze the costs and 40 benefits involved in using either bioremediation technique.