title: Mangrove bacterial diversity and the impact of oil contamination revealed by pyrosequencing: bacterial proxies for oil pollution.
abstract: BACKGROUND
  Mangroves are transitional coastal ecosystems in tropical and sub-tropical regions and represent biologically important and productive ecosystems. Despite their great ecological and economic importance, mangroves are often situated in areas of high anthropogenic influence, being exposed to pollutants, such as those released by oil spills.
  
  
  RESULTS
  A microcosm experiment was conducted, which simulated an oil spill in previously pristine mangrove sediment. The effect of the oil spill on the extant microbial community was studied using direct pyrosequencing. Extensive bacterial diversity was observed in the pristine mangrove sediment, even after oil contamination. The number of different OTUs only detected in contaminated samples was significantly higher than the number of OTUs only detected in non-contaminated samples. The phylum Proteobacteria, in particular the classes Gammaproteobacteria and Deltaproteobacteria, were prevalent before and after the simulated oil spill. On the other hand, the order Chromatiales and the genus Haliea decreased upon exposure to 2 and 5% oil, these are proposed as sensitive indicators of oil contamination. Three other genera, Marinobacterium, Marinobacter and Cycloclasticus increased their prevalence when confronted with oil. These groups are possible targets for the biomonitoring of the impact of oil in mangrove settings.
  
  
  CONCLUSIONS
  We suggest the use of sequences of the selected genera as proxies for oil pollution, using qPCR assessments. The quantification of these genera in distinct mangrove systems in relation to the local oil levels would permit the evaluation of the level of perturbance of mangroves, being useful in field monitoring. Considering the importance of mangroves to many other environments and the susceptibility of such areas to oil spills this manuscript will be of broad interest.
authors.affiliation: Laboratory of Molecular Microbial Ecology, Departamento of General Microbiology, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Henrique Fragoso
authors.initials: HF
authors.lastname: dos Santos
authors.forename: Juliano Carvalho
authors.initials: JC
authors.lastname: Cury
authors.forename: Flávia Lima
authors.initials: FL
authors.lastname: do Carmo
authors.forename: Adriana Lopes
authors.initials: AL
authors.lastname: dos Santos
authors.forename: James
authors.initials: J
authors.lastname: Tiedje
authors.forename: Jan Dirk
authors.initials: JD
authors.lastname: van Elsas
authors.forename: Alexandre Soares
authors.initials: AS
authors.lastname: Rosado
authors.forename: Raquel Silva
authors.initials: RS
authors.lastname: Peixoto
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D044822:Biodiversity; D004787:Environmental Pollution / Q000009:adverse effects* / Q000032:analysis; D006838:Hydrocarbons / Q000032:analysis; D008969:Molecular Sequence Data; D009821:Oils / Q000009:adverse effects* / Q000032:analysis; D010578:Petroleum / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D043982:Rhizophoraceae / Q000382:microbiology*; D017422:Sequence Analysis, DNA / Q000379:methods*; D013696:Temperature
chemical_list: D006838:Hydrocarbons; D009821:Oils; D010578:Petroleum; D012336:RNA, Ribosomal, 16S