title: Different susceptibilities of bacterial community to silver nanoparticles in wastewater treatment systems.
abstract: The release of silver (Ag) nanoparticles (NPs) into sewage streams has heightened concerns about potential adverse impacts on wastewater treatment processes. Here, we show that the rate constants of both biological nitrification and organic oxidation decreased exponentially with an increase in the Ag NP concentration, but nitrification was more severely inhibited than the organic oxidation even at low Ag NP concentrations (<1 mg Ag L(-1)) in batch experiments. The long-term exposure effects of Ag NPs on activated sludge bacteria were evaluated in sequencing batch reactors (SBRs) fed with two different substrates favoring heterotrophic and autotrophic bacteria. From a continuous operation for 50 days, it was found that heterotrophic bacteria in the organic removal process have higher tolerance to Ag NPs than do nitrifying bacteria. The effects of Ag NPs on the microbial community in both SBRs were analyzed using 16S ribosomal ribonucleic acid (rRNA) gene sequences obtained from pyrosequencing. The results showed that the level of microbial susceptibility is different for each type of microorganism and that the microbial diversity decreased dramatically after continuous exposure to Ag NPs for 50 days, resulting in a decrease of wastewater treatment efficiency.
authors: a Center for Water Resource Cycle Research, Korea Institute of Science and Technology (KIST) , Seongbuk-gu , Seoul , Republic of Korea.
authors: Emma
authors: E
authors: Jeong
authors: Wan-Tack
authors: WT
authors: Im
authors: Dong-Hoon
authors: DH
authors: Kim
authors: Mi-Sun
authors: MS
authors: Kim
authors: Seoktae
authors: S
authors: Kang
authors: Hang-Sik
authors: HS
authors: Shin
authors: So-Ryong
authors: SR
authors: Chae
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D019149:Bioreactors; D024881:Drug Resistance, Bacterial; D014644:Genetic Variation; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D058465:Nitrification / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology; D012834:Silver / Q000737:chemistry / Q000633:toxicity*; D013045:Species Specificity; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis*
chemical_list: D012336:RNA, Ribosomal, 16S; D012722:Sewage; D012834:Silver; D062065:Wastewater