Diversity in Soil Bacterial Community Using PCR-DGGE Technique in Constructed Wetlands Receiving Swine Wastewater.

Constructed wetland provides a feasible option for removal of contaminants from anaerobic lagoon animal wastewater before land application. The goal of our study was to characterize the diversity in soil bacterial community in different sections of a constructed wetland which was designed to treat swine wastewater. Surface soil samples were collected and analyzed by using culture-dependent and culture-independent techniques. Changes in the bacterial community located in different sections of the wetland were examined by the use of PCR-DGGE (denaturing gradient gel electrophoresis) technique. Wetland samples and bacterial cultures showed different DGGE patterns which were corresponding to different nutrient status distributed in the wetland system. Cluster analysis and multidimensional scaling analysis were performed to compare bacterial community structures displayed on DGGE profiles. Partial 16S rDNA sequences revealed that the total bacterial community composition was dominated by Pseudomonas anguilliseptica, Arthrobacter nicotianae, Bacillus cereus, and others. Phosphate solubilizing bacteria Bacillus megaterium, and potential denitrifying bacterium Flavobacterium sp were detected. Phylogenetic analysis demonstrated that uncultured bacteria P16 (EU220712), P20 (EU220716), P21(EU220717) and P22(EU220718) had close relationships with different unculturable denitrification bacteria, and P19(EU220715) was homologous to unculturable potential anammox (anaerobic ammonium oxidation) bacterium stain AB376613. The activities of these bacteria might well contribute to the nutrient removal in our wetland. The combination of culture-dependent and culture-independent methods provided complementary information and helped to overcome the limitations inherent in each of them.