title: Abundance and diversity of Sphingomonas in Shenfu petroleum-wastewater irrigation zone, China.
abstract: BACKGROUND
  Members of the genus Sphingomonas have raised increasing attention due to their ability for polycyclic aromatic hydrocarbon (PAH) degradation and their ubiquity in the environment. However, few studies have revealed the ecological information on the abundance and diversity of Sphingomonas in the environment.
  
  
  METHODS
  A primer set targeting the Sphingomonas 16S rRNA gene was designed. The specificity was tested with four petroleum-contaminated soils by construction of clone libraries and further restriction fragment length polymorphism analysis. Subsequently, real time PCR and denaturing gradient gel electrophoresis (DGGE) assays were used to evaluate the abundance and diversity of Sphingomonas in the Shenfu irrigation zone, China.
  
  
  RESULTS
  A genus-specific primer set SA/429f-933r was developed, and 90% of the sequences retrieved from soil clone libraries were related to Sphingomonas. Members of the genus Sphingomonas were detected in all soils, and significant correlation (p < 0.05) was observed between the Sphingomonas abundance and the ratios of PAHs to total petroleum hydrocarbon (TPH). DGGE profiles revealed Sphingomonas population structures differed greatly in different sites. The Sphingomonas diversity was not statistically (p > 0.05) correlated with the contamination level. Some of the soil-derived sequences were not grouped phylogenetically with sequences of known Sphingomonas, indicating new members of the Sphingomonas genus might be present in the Shenfu irrigation zone.
  
  
  CONCLUSIONS
  The newly designed Sphingomonas-selective primers were specific and practicable for analyzing Sphingomonas abundance and diversity in petroleum-contaminated soils. The significant correlation between the abundance and the ratios of PAHs to TPH suggested an important role of Sphingomonas in PAH bioremediation.
authors: Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors: Lisha
authors: L
authors: Zhou
authors: Hui
authors: H
authors: Li
authors: Ying
authors: Y
authors: Zhang
authors: Yafei
authors: Y
authors: Wang
authors: Siqin
authors: S
authors: Han
authors: Hui
authors: H
authors: Xu
mesh_terms: D057914:Agricultural Irrigation / Q000379:methods*; D001673:Biodegradation, Environmental; D002681:China; D010578:Petroleum / Q000633:toxicity*; D011084:Polycyclic Aromatic Hydrocarbons / Q000633:toxicity; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012989:Soil Pollutants / Q000633:toxicity*; D020578:Sphingomonas / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010578:Petroleum; D011084:Polycyclic Aromatic Hydrocarbons; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical