Comparison of bacterial diversity of polluted and unpolluted sediment by brominated flame retardant

Objective: By using brominated flame retardant we compared the bacterial diversity of highly polluted river sediment with that of nearby unpolluted lake.

Methods: Total DNA was extracted from unpolluted and highly polluted sediment sample by brominated flame retardant in Guiyu of China. The 16S rRNA gene was amplified by PCR using bacterial primer 27F and 1500R. The plasmid libraries of the amplicons were constructed. The positive clones with insert were screened on plates with IPTG/X-gal/Ap. Amplified ribosmal DNA restriction analysis (ARDRA) was carried out with restriction enzymes Hha I and Hinf I. Representative clones of each operational taxonomic unit based on the ARDRA patterns were selected to be sequenced. After proof reading and careful comparison to remove the chimeric sequences, the partial sequence of 16S rRNA gene were used for construction of the phylogenetic tree.

Results: The result of blast searching showed that clones from unpolluted sediment sample belonged to alpha-Proteobacteria, beta-Proteobacteria, gamma-Proteobacteria, delta-Proteobacteria, Planctomycetes, Acidobacteria, Actinobacteria, Chloroflexi, Verrucomicrobia, Firmicutes, the predominant bacteria (30.2% of total clones) is Acidobacteria; most clones from polluted sediment belonged to alpha-Proteobacteria, beta-Proteobacteria, epsilon-Proteobacteria, delta-Proteobacteria, Planctomycetes, Acidobacteria, Actinobacteria, Chloroflexi, Bacteroidetes, Firmicutes, candidate division 0P01, candidate division OP08, the predominant bacteria (44.9% of total clones) are epsilon-Proteobacteria and Chloroflexi.

Conclusions: Bacterial community structure of polluted sediment has distinguished feature and obviously different from the unpolluted sediment sample, which is mainly reflected in the dominant position of epsilon-Proteobacteria and Chloroflexi in the bacterial flora.