Diversity and bacteria community structure of activated carbon used in advanced drinking water treatment

Two granular activated carbon(GAC) samples with 1.5 a and 5 a age were collected,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 two activated carbon biofilm sample were studied.The results showed the bacteria in GAC with 5 a age could be divided into 11 groups,which were as follows α-Proteobacteria(26.5%),β-Proteobacteria(16.3%),δ-Proteobacteria(16.3%),Planctomycetes(12.2%),Gemmatimonadetes(6.1%),Acidobacteria(4.1%),Nitrospira(2.0%),γ-Proteobacteria(2.0%),Bacteroidetes(2.0%),Actinobacteria(2.0%),Unclassified Bacteria(10.2%).The bacteria in GAC with 1.5 a age could be divided into 10 groups,which were as follows α-Proteobacteria(21.6%),Planctomycetes(10.8%),Bacteroidetes(10.8%),β-Proteobacteria(9.0%),Acidobacteria(9.0%),Nitrospira(7.2%),δ-Proteobacteria(7.2%),Unclassified Proteobacteria(5.4%),Gemmatimonadetes(3.6%),Unclassified Bacteria(14.4%).The results revealed a variety of bacterial divisions on the studied GAC biofilm.Proteobacteria had the highest share in the two total clones,and α-and β-Proteobacteria were on a dominant position.A relatively high proportion of δ-Proteobacteria was observed in the biofilm of GAC with 5 a age,and Nitrospira was in a minor proportion.However,a totally converse condition appeared in GAC with 1.5 a age.Two pathogenic bacteria,Afipia and Chryseobacterium,were detected in analyzed GACs,which implies a potential microbial risk in water supply.