Kinetics and pathway of biodegradation of dibutyl phthalate by Pleurotus ostreatus Miriam Ahuactzin-P  erez c, d , Saúl Tl  ecuitl-Beristain e , Jorge García-D  avila e , Ericka Santacruz-Ju  arez e , Manuel Gonz  alez-P  erez f , María Concepci  on Guti  errez-Ruíz b , Carmen S  anchez a, * a Laboratory of Biotechnology, Research Centre for Biological Sciences, Universidad Aut onoma de Tlaxcala, Ixtacuixtla, Tlaxcala, CP 90062, Mexico b Departamento de Ciencias de la Salud, Universidad Aut onoma Metropolitana-Iztapalapa, CDMX, Mexico c Doctorado en Biología Experimental, Universidad Aut onoma Metropolitana-Iztapalapa (UAM-I), Mexico d Facultad de Agrobiología, Universidad Aut onoma de Tlaxcala, Ixtacuixtla, Tlaxcala, Mexico e Universidad Polit ecnica de Tlaxcala, San Pedro Xalcatzinco, Tepeyanco, Tlaxcala, CP 90180, Mexico f Universidad Popular Aut onoma del Estado de Puebla, Puebla, CP 72410, Mexico article info Article history: Received 27 May 2018 Received in revised form 27 June 2018 Accepted 2 July 2018 Available online xxx Corresponding Editor: Julian Rutherford Keywords: Basidiomycete Biodegradation pathway Constant of biodegradation Plasticizer Removal efficiency abstract Dibutyl phthalate (DBP) is a plasticizer, whose presence in the environment as a pollutant has attained a great deal of attention due to its reported association with endocrine system disturbances on animals. Growth parameters, glucose uptake, percentage of removal efficiency (%E) of DBP, biodegradation con- stant of DBP (k) and half-life of DBP biodegradation (t 1/2 ) were evaluated for Pleurotus ostreatus grown on media containing glucose and different concentrations of DBP (0, 500 and 1000 mg l 1 ). P . ostreatus degraded 99.6 % and 94 % of 500 and 1000 mg of DBP l 1 after 312 h and 504 h, respectively. The k was 0.0155 h 1 and 0.0043 h 1 for 500 and 1000 mg of DBP l 1 , respectively. t 1/2 was 44.7 h and 161 h for 500 and 1000 mg of DBP l 1 , respectively. Intermediate compounds of biodegraded DBP were identified by GC-MS and a DBP biodegradation pathway was proposed using quantum chemical calculation. DBP might be metabolized to benzene and acetyl acetate, the first would be oxidated to muconic acid and the latter would enter into the Krebs cycle. P . ostreatus has the ability to degrade DBP and utilizes it as source of carbon and energy. © 2018 British Mycological Society. Published by Elsevier Ltd. All rights reserved. 1. Introduction Phthalates are a family of industrial compounds with a common chemical structure, dialkyl or alkyl/aryl esters of 1,2- benzenedicarboxylic acid. They are plasticizers that are added to plastics to make them soft and flexible. Low molecular weight phthalates, such as dibutyl phthalate (DBP), are used to impart flexibility to thin films. DBP is used as a solvent in personal-care products (e.g. perfumes, lotions), printing inks and resin solvents (Meeker et al., 2009; P erez-Andr es et al., 2017). DBP is one of the predominant phthalate esters present in atmospheric particles as well as in fresh water and sediments (Gao and Wen, 2016). DBP can be taken up by plants and other living organisms, thereby entering the food supply in both marine and fresh environments (Muneer et al., 2001). Several studies have shown that DBP has anti- androgenic and estrogenic effects in male rats and fish and has also been reported to cause reproductive defects in humans (Chen et al., 2014; Xu et al., 2014). It has been reported that shorter ester chains like DBP can be easier to biodegrade and mineralize than phthalates with long ester chains such as di (2-ethyl hexyl) phthalate (DEHP) (Liang et al., 2008). Therefore, the occurrence of phthalate esters in the environment depends on their use, pro- duction and biodegradability. The hydrolysis and photolysis of phthalate esters are very slow. Microbial degradation plays a major role in mineralizing phthalate esters in the environment (Prasad and Suresh, 2012; Pradeep et al., 2013; Ahuactzin-P erez et al., 2014; Bouchiat et al., 2015; Meng et al., 2015). Bhardwaj et al. Abbreviations: DBP, dibutyl phthalate; m, specific growth rate; X max , maximum biomass; k, constant of biodegradation; t 1/2 , half-life of DBP biodegradation; HOMO, highest occupied molecular orbital; LUMO, lowest unoccupied molecular orbital; Ed, electrostatic potential; dþ, molecular partial positive charge; d-, molecular partial negative charge; E Bg , energy of band gap; ETC, electron transfer coefficient. * Corresponding author. E-mail address: sanher6@hotmail.com (C. S anchez). Contents lists available at ScienceDirect Fungal Biology journal homepage: www.elsevier.com/locate/funbio https://doi.org/10.1016/j.funbio.2018.07.001 1878-6146/© 2018 British Mycological Society. Published by Elsevier Ltd. All rights reserved. Fungal Biology xxx (2018) 1e7 Please cite this article in press as: Ahuactzin-P erez, M., et al., Kinetics and pathway of biodegradation of dibutyl phthalate by Pleurotus ostreatus, Fungal Biology (2018), https://doi.org/10.1016/j.funbio.2018.07.001