Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 392573, 9 pages http://dx.doi.org/10.1155/2013/392573 Research Article Enhanced Removal of a Pesticides Mixture by Single Cultures and Consortia of Free and Immobilized Streptomyces Strains María S. Fuentes, 1 Gabriela E. Briceño, 2,3 Juliana M. Saez, 1 Claudia S. Benimeli, 1,4,5 María C. Diez, 2 and María J. Amoroso 1,4,6 1 Planta Piloto de Procesos Industriales Microbiol´ ogicos (PROIMI-CONICET), Avenida Belgrano y Pasaje Caseros, 4000 Tucum´ an, Argentina 2 N´ ucleo de Desarrollo Cient´ ıfco Tecnol´ ogico, Universidad de La Frontera, Avenida Francisco Salazar 01145, 4780000 Temuco, Chile 3 Departamento de Ingenier´ ıa Qu´ ımica, Universidad de La Frontera, Avenida Francisco Salazar 01145, 4780000 Temuco, Chile 4 Universidad del Norte Santo Tom´ as de Aquino, 9 de Julio 165, 4000 Tucum´ an, Argentina 5 Unidad de Administraci´ on Territorial, Centro Cient´ ıfco Tecnol´ ogico, CONICET-Tucum´ an, Cris´ ostomo ´ Alvarez 722, 4000 Tucum´ an, Argentina 6 Facultad de Bioqu´ ımica, Qu´ ımica y Farmacia, Universidad Nacional de Tucum´ an, Ayacucho 491, 4000 Tucum´ an, Argentina Correspondence should be addressed to Mar´ ıa J. Amoroso; mjamoroso@ciudad.com.ar Received 24 April 2013; Revised 7 June 2013; Accepted 13 June 2013 Academic Editor: Kannan Pakshirajan Copyright © 2013 Mar´ ıa S. Fuentes et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pesticides are normally used to control specifc pests and to increase the productivity in crops; as a result, soils are contaminated with mixtures of pesticides. In this work, the ability of Streptomyces strains (either as pure or mixed cultures) to remove pentachlorophenol and chlorpyrifos was studied. Te antagonism among the strains and their tolerance to the toxic mixture was evaluated. Results revealed that the strains did not have any antagonistic efects and showed tolerance against the pesticides mixture. In fact, the growth of mixed cultures was signifcantly higher than in pure cultures. Moreover, a pure culture (Streptomyces sp. A5) and a quadruple culture had the highest pentachlorophenol removal percentages (10.6% and 10.1%, resp.), while Streptomyces sp. M7 presented the best chlorpyrifos removal (99.2%). Mixed culture of all Streptomyces spp. when assayed either as free or immobilized cells showed chlorpyrifos removal percentages of 40.17% and 71.05%, respectively, and for pentachlorophenol 5.24% and 14.72%, respectively, suggesting better removal of both pesticides by using immobilized cells. Tese results reveal that environments contaminated with mixtures of xenobiotics could be successfully cleaned up by using either free or immobilized cultures of Streptomyces, through in situ or ex situ remediation techniques. 1. Introduction Te agriculture sector is a very important part of the economy and provides foods and raw materials needed for a sustainable development. For this reason, this sector uses diferent resources as pesticides, chemical fertilizers, equipment, and machines [1]. Pesticides are usually applied simultaneously or one afer another for crop protection, and this type of pesticide application ofen leads to a combined contamina- tion of these compound residues in the soil environment [2]. Among the pesticides, compounds such as organochlo- rines, organophosphates, carbamates, and pyrethroids are commonly used in vegetables and other crops, in order to increase the productivity [3]. As a result, an increase in the pesticide application translates into an increase in their residues in all spheres of environment [4], especially in agricultural soils. Because of the restriction imposed on toxic organophos- phate compounds, chlorpyrifos (CP), a broad-spectrum and moderately toxic organophosphate insecticide, has gained the status of one of the most widely used commercial compounds [5]. Te widespread use of this pesticide and its resulting residues, which accumulates on agricultural crops, produces an increase of not only environmental contamination but