Romanian Biotechnological Letters Vol. 21, No. 1, 2016 Copyright © 2016 University of Bucharest Printed in Romania. All rights reserved ORIGINAL PAPER 11194 Romanian Biotechnological Letters, Vol. 21, No. 1, 2016 Degradation of Phenanthrene by Natural Consortia in Seawater Received for publication, November 12, 2014 Accepted, February 10, 2015 GARCÍA-UITZ K. 1 ; MORENO-ANDRADE I. 2 ; HERNANDEZ-NUÑEZ E. 3 ; CORONA-CRUZ A. 4 ; GIACOMÁN-VALLEJOS G. 5 ; PONCE-CABALLERO C. 6 1 Health Sciences Division, University of Quintana Roo (UQROO), Chetumal 77039, Mexico. 3,5,6 Faculty of Engineering. University Autonomous of Yucatan. Industrias no Contaminantes S/N por Periférico Norte.CP. 97310, Mérida, Yucatán, México. 2 Laboratory for Research on Advanced Processes for Water Treatment, Instituto de Ingeniería, Unidad Académica Juriquilla, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, Querétaro 76230, Mexico. 4 Faculty of Chemical Engineering. University Autonomous of Yucatan. Periférico Norte Km 33.5. CP. 97203, Mérida, Yucatán, México. * Correspondence address to: Tel: + 52(999) 1580741. E-mail: garciauk@hotmail.com Abstract In this study 17 aerobic bacterial consortia were isolated from seawater and sediments; the culture medium was enriched with phenanthrene to evaluate the potential degradation of this pollutant. The consortia were evaluated for their ability to degrade phenanthrene as the only source of carbon and energy in synthetic seawater. The percentage degradation of the consortium S4 was 75% after 7 days of incubation (100mgL -1 ), with a specific microbial growth rate of 0.031 h -1 at 33°C+ 3° and 150 r min -1 . Keywords: phenanthrene, consortia, seawater, biodegradation 1. Introduction The phenanthrene is a simple polycyclic aromatic hydrocarbon(PAHs), that is more distributed in nature, as it is a component of fossil fuels and which is formed by incomplete combustion of organic matter (JUHASZ AND NAIDU [5]). Therefore this compound has been used as a model for studies of biodegradation of polycyclic aromatic hydrocarbons by bacteria (MROZIK AND PIOTROWSKA-SEGET [9]). The phenanthrene contains in its structure three fused benzene rings and a region-bay and a region-K, which gives the characteristic of being highly reactive chemically and biologically, is considered a dangerous pollutant to aquatic life, plants and other organisms and has often been mentioned as one of the 16 PAHs, which may be carcinogenic. The degradation of this pollutant is necessary to preserve the environment and human. SCHVOERER & al. [13] presented an investigation on human health risk assessment, their results indicated that 7.5% of the individuals experienced some type of wound and 53% some health problem (30% lumbar pain, 22% migraine, 16% dermatitis) and in a smaller degree ocular irritation (9%), respiratory problems (7%) and nausea (6%). Differentbacteria as Sphingomonas sp. Pseudomonas sp. Staphylococcus sp. Bacillus sp. Nocardioides sp. among others, are known as phenanthrene degraders, which can mineralize low molecular weight hydrocarbons (MALLICK & al. [8]; DODDAMANI AND NINNEKAR [2]; SAITO & al. [12]; TAO & al. [15]; PRABHU AND PHALE [10]). Bacteria are an essential component in the food chain, through their interaction with other organisms, result in changes in their environment and are able to grow in polluted environments (BOSCHKER & al. [1]). In general, biodegradation with pure strains is not the actual behavior of the microorganisms in the environment; bioremediation actually depends on the interaction of the metabolic activities