Bacterial biodiversity in the groundwater contaminated by oil

An oil-contaminated groundwater sample was collected at an abandoned petrochemical factory.Bacterial genome DNA was extracted for the 16S rDNA gene amplification,and then a bacterial 16S rDNA gene clone library was constructed. After the phylogenetic analysis of 16S rDNA sequences, bacterial diversity and community structure of the groundwater were studied. The results showed the bacteria in the groundwater could be divided into 10 groups, which were as follows: gamma-Proteobacteria (49.1%), alpha-Proteobacteria (12.9%), beta-Proteobacteria (11.1%), Bacteroidetes (9.2%), Verrucomicrobia (6.7%), Acidobacteria (2.5%), delta-Proteobacteria (1.2%), Actinobacteria (1.2%), Planctomycetes (0.6%), unidentified bacteria (5.5%). Gamma-Proteobacteria was predominant in the ecosystem (near 50% of total clones), and especially Pseudomonas accounted for 35.6% of all bacteria. Many clones also affiliated with other degrading bacteria,such as Sphingomornas, Rhodococcus, Brevundimonas. Furthermore, a lot of 16S rDNA sequences in the clone library had high similarity to the ones originated from similar polluted environments, such as soil and groundwater contaminated with chlorinated hydrocarbon, soil and groundwater contaminated with polycyclic aromatic hydrocarbon, soil contaminated with PCBs, antibiotics production wastewater and activated sludge, which proved that there were lots of degrading bacteria population in the oil-contaminated water.