Microbial Diversity of the Daqing Oilfi eld after Polymer Flooding

DNA was extracted from four oil well samples after polymer flooding in the Daqing Oilfi eld, Heilongjiang, China. A 16S rDNA clone library was constructed by PCR amplification with universal primers, cloned in Escherichia coli and characterized subsequently by amplifi ed rDNA restriction analysis (ARDRA). 298 clones were obtained and classifi ed into 22 different operational taxonomic units (OTUs). Four OTUs occupied 78.18 of the 16S rDNA clone library, while nine OTUs had only one clone. At the same time, the microbial diversity of the 16S rDNA clone library was evaluated by coverage value (C), Shannon Weiner index (H) and evenness index (E). Phylogenetic analysis revealed that the dominant microbes of the library belonged to Alphaproteobacteria (24.83%), Gammaproteobacteria (23.49%), Deltaproteobacteria (34.56%) and the uncultured bacteria (16.78%). Pseudomonas and Acinetobacter related with hydrocarbon biodegradation and surfactant production accounted for 17.79% and 6.02% in the clone library, respectively. Fig 4, Tab 2, Ref 19