title: Impact of hydrocarbons, PCBs and heavy metals on bacterial communities in Lerma River, Salamanca, Mexico: Investigation of hydrocarbon degradation potential.
abstract: Freshwater contamination usually comes from runoff water or direct wastewater discharges to the environment. This paper presents a case study which reveals the impact of these types of contamination on the sediment bacterial population. A small stretch of Lerma River Basin, heavily impacted by industrial activities and urban wastewater release, was studied. Due to industrial inputs, the sediments are characterized by strong hydrocarbon concentrations, ranging from 2 935 to 28 430μg·kg(-1) of total polyaromatic hydrocarbons (PAHs). These sediments are also impacted by heavy metals (e.g., 9.6μg·kg(-1) of Cd and 246μg·kg(-1) of Cu, about 8 times the maximum recommended values for environmental samples) and polychlorinated biphenyls (ranging from 54 to 123μg·kg(-1) of total PCBs). The bacterial diversity on 6 sediment samples, taken from upstream to downstream of the main industrial and urban contamination sources, was assessed through TRFLP. Even though the high PAH concentrations are hazardous to aquatic life, they are not the only factor driving bacterial community composition in this ecosystem. Urban discharges, leading to hypoxia and low pH, also strongly influenced bacterial community structure. The bacterial bioprospection of these samples, using PAH as unique carbon source, yielded 8 hydrocarbonoclastic strains. By sequencing the 16S rDNA gene, these were identified as similar to Mycobacterium goodii, Pseudomonas aeruginosa, Pseudomonas lundensis or Aeromonas veronii. These strains showed high capacity to degrade naphthalene (between 92 and 100% at 200mg·L(-1)), pyrene (up to 72% at 100mg·L(-1)) and/or fluoranthene (52% at 50mg·L(-1)) as their only carbon source on in vitro experiments. These hydrocarbonoclastic bacteria were detected even in the samples upstream of the city of Salamanca, suggesting chronical contamination, already in place longer before. Such microorganisms are clearly potential candidates for hydrocarbon degradation in the treatment of oil discharges.
authors.affiliation: Ingeniería Ambiental, Depto. Ing. Civil, DI-CGT, Universidad de Guanajuato, Guanajuato, Gto, Mexico. Electronic address: emsbrito@gmail.com.
authors.forename: Elcia M S
authors.initials: EM
authors.lastname: Brito
authors.affiliation: Ingeniería Ambiental, Depto. Ing. Civil, DI-CGT, Universidad de Guanajuato, Guanajuato, Gto, Mexico.
authors.forename: Magali
authors.initials: M
authors.lastname: De la Cruz Barrón
authors.affiliation: Depto. Astronomía, DCNyE-CGT, Universidad de Guanajuato, Gto, Mexico.
authors.forename: César A
authors.initials: CA
authors.lastname: Caretta
authors.affiliation: Equipe Environnement et Microbiologie (EEM-UMR-IPREM), Universitè de Pau et des Pays de l'Adour, Pau, France.
authors.forename: Marisol
authors.initials: M
authors.lastname: Goñi-Urriza
authors.affiliation: Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Leandro H
authors.initials: LH
authors.lastname: Andrade
authors.affiliation: Ingeniería Ambiental, Depto. Ing. Civil, DI-CGT, Universidad de Guanajuato, Guanajuato, Gto, Mexico.
authors.forename: Germán
authors.initials: G
authors.lastname: Cuevas-Rodríguez
authors.affiliation: Inst. Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Olaf
authors.initials: O
authors.lastname: Malm
authors.affiliation: Inst. Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: João P M
authors.initials: JP
authors.lastname: Torres
authors.affiliation: Equipe Environnement et Microbiologie (EEM-UMR-IPREM), Universitè de Pau et des Pays de l'Adour, Pau, France.
authors.forename: Maryse
authors.initials: M
authors.lastname: Simon
authors.affiliation: Equipe Environnement et Microbiologie (EEM-UMR-IPREM), Universitè de Pau et des Pays de l'Adour, Pau, France.
authors.forename: Remy
authors.initials: R
authors.lastname: Guyoneaud
mesh_terms: D004784:Environmental Monitoring; D019216:Metals, Heavy / Q000032:analysis / Q000633:toxicity*; D008800:Mexico; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000633:toxicity*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000633:toxicity*; D045483:Rivers / Q000737:chemistry / Q000382:microbiology; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D019216:Metals, Heavy; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
keywords: Freshwater; Heavy metals; Hydrocarbonoclastic bacteria; Oil contamination; PCBs