%0 Journal Article
%T Biodegradation of Polyethoxylated Nonylphenols
%A Yassellis Ruiz
%A Luis Medina
%A Margarita Borusiak
%A Nairalith Ramos
%A Gilberto Pinto
%A Oscar Valbuena
%J ISRN Microbiology
%D 2013
%R 10.1155/2013/284950
%X Polyethoxylated nonylphenols, with different ethoxylation degrees ( ), are incorporated into many commercial and industrial products such as detergents, domestic disinfectants, emulsifiers, cosmetics, and pesticides. However, the toxic effects exerted by their degradation products, which are persistent in natural environments, have been demonstrated in several animal and invertebrate aquatic species. Therefore, it seems appropriate to look for indigenous bacteria capable of degrading native and its derivatives. In this paper, the isolation of five bacterial strains, capable of using , as unique carbon source, is described. The most efficient degrader bacterial strains were identified as Pseudomonas fluorescens (strain Yas2) and Klebsiella pneumoniae (strain Yas1). Maximal growth rates were reached at pH 8, 27¡ãC in a 5% medium. The degradation extension, followed by viscometry assays, reached 65% after 54.5£¿h and 134£¿h incubation times, while the COD values decreased by 95% and 85% after 24£¿h for the Yas1 and Yas2 systems, respectively. The BOD was reduced by 99% and 99.9% levels in 24£¿h and 48£¿h incubations. The viscosity data indicated that the biodegradation by Yas2 follows first-order kinetics. Kinetic rate constant ( ) and half life time ( ) for this biotransformation were estimated to be 0.0072£¿h£¿1 and 96.3£¿h, respectively. 1. Introduction Alkyl polyethoxylates (APEO), widely used as industrial and domestic surfactants, are added to a variety of products such as dispersants, emulsifiers, detergents, dyes, antioxidants, pesticides, spermicides, and cosmetics [1¨C4]. Most of these compounds including nonylphenol polyethoxylates ( ) are incorporated to aqueous solutions, and after being used, they are discharged in industrial or municipal water waste and eventually enter water treatment plants [5, 6]. Due to their persistency at low temperatures remain in the environment and could be bioaccumulated, which is harmful to animals, humans, and other biological aquatic species [7¨C10], as its degradation products are more toxic than the original molecule [1, 3, 8, 11¨C13]. The toxic effects exerted by and its degradation products include reduction of spermatozoid number, increase of testicular cancer, and feminism in aquatic male species [7, 8, 14, 15]. The highly ethoxylated compounds lack estrogenic activity, whereas the low ethoxylated ones, included nonylphenol, which arise from nonylphenol ethoxylates by degradation in natural environments, do affect fishes, amphibians, birds, mammalians, invertebrates species such as crustaceans, mollusks, algae, yeast,
%U http://www.hindawi.com/journals/isrn.microbiology/2013/284950/