Distribution patterns of denitrification functional genes and microbial floras in multimedia constructed wetlands

The present study, a quantitative investigation of distribution patterns of functional gene communities, including Anammox bacteria 16S rRNA, amoA, nxrA, narG, napA, nirK, qnorB, nosZ, nas, and nifH in two multimedia constructed wetland systems (CWs) was conducted. DGGE results showed similar distribution patterns in two constructed wetland groups. Lactococcus sp. and Moraxella sp. were the dominant organic nitrogen and denitrification flora; Acinetobacter sp. were the dominant NO3− to NH4+ transformation flora; and Bacillus sp. and β-Proteobacteria sp. were the dominant NH4+ removal flora in the two constructed wetland groups. Quantitative real-time PCR results showed the qnorB and nas functional genes were predominantly enriched in the 15 cm and 60 cm layers of the CW, which was prepared by multi-media packing of 1% zero-valent iron. The nirK was predominantly enriched in the 60 cm layer of the CW, which was prepared by multi-media packing of 2% zero-valent iron. Other functional nitrogen transformation genes were predominantly enriched in the 15 cm layer of CWs.