title: Changes in the structure and function of microbial communities in drinking water treatment bioreactors upon addition of phosphorus.
abstract: Phosphorus was added as a nutrient to bench-scale and pilot-scale biologically active carbon (BAC) reactors operated for perchlorate and nitrate removal from contaminated groundwater. The two bioreactors responded similarly to phosphorus addition in terms of microbial community function (i.e., reactor performance), while drastically different responses in microbial community structure were detected. Improvement in reactor performance with respect to perchlorate and nitrate removal started within a few days after phosphorus addition for both reactors. Microbial community structures were evaluated using molecular techniques targeting 16S rRNA genes. Clone library results showed that the relative abundance of perchlorate-reducing bacteria (PRB) Dechloromonas and Azospira in the bench-scale reactor increased from 15.2% and 0.6% to 54.2% and 11.7% after phosphorus addition, respectively. Real-time quantitative PCR (qPCR) experiments revealed that these increases started within a few days after phosphorus addition. In contrast, after phosphorus addition, the relative abundance of Dechloromonas in the pilot-scale reactor decreased from 7.1 to 0.6%, while Zoogloea increased from 17.9 to 52.0%. The results of this study demonstrated that similar operating conditions for bench-scale and pilot-scale reactors resulted in similar contaminant removal performances, despite dramatically different responses from microbial communities. These findings suggest that it is important to evaluate the microbial community compositions inside bioreactors used for drinking water treatment, as they determine the microbial composition in the effluent and impact downstream treatment requirements for drinking water production. This information could be particularly relevant to drinking water safety, if pathogens or disinfectant-resistant bacteria are detected in the bioreactors.
authors.affiliation: Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI 48109, USA. raskin@umich.edu
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Giridhar
authors.initials: G
authors.lastname: Upadhyaya
authors.forename: Wangki
authors.initials: W
authors.lastname: Yuen
authors.forename: Jess
authors.initials: J
authors.lastname: Brown
authors.forename: Eberhard
authors.initials: E
authors.lastname: Morgenroth
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Raskin
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics*; D044822:Biodiversity; D019149:Bioreactors; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D010472:Perchlorates / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism; D018508:Water Purification
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D009566:Nitrates; D010472:Perchlorates; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D010758:Phosphorus; C494474:perchlorate