Effects of ammonium and nitrite on communities and populations of ammonia-oxidizing bacteria in laboratory-scale continuous-flow reactors.
This study investigated the effects of ammonium and nitrite on ammonia-oxidizing bacteria (AOB) from an activated sludge process in laboratory-scale continuous-flow reactors. AOB communities were analyzed using specific PCR followed by denaturing gel gradient electrophoresis, cloning and sequencing of the 16S rRNA gene, and AOB populations were quantified using real-time PCR. To study the effect of ammonium, activated sludge from a sewage treatment system was enriched in four reactors receiving inorganic medium containing four different ammonium concentrations (2, 5, 10 and 30 mM NH(4) (+)-N). One of several sequence types of the Nitrosomonas oligotropha cluster predominated in the reactors with lower ammonium loads (2, 5 and 10 mM NH(4) (+)-N), whereas Nitrosomonas europaea was the dominant AOB in the reactor with the highest ammonium load (30 mM NH(4) (+)-N). The effect of nitrite was studied by enriching the enriched culture possessing both N. oligotropha and N. europaea in four reactors receiving 10-mM-ammonium inorganic medium containing four different nitrite concentrations (0, 2, 12 and 22 mM NO(2) (-)-N). Nitrosomonas oligotropha comprised the majority of AOB populations in the reactors without nitrite accumulation (0 and 2 mM NO(2) (-)-N), whereas N. europaea was in the majority in the 12- and 22-mM NO(2) (-)-N reactors, in which nitrite concentrations were 2.1-5.7 mM (30-80 mg N L(-1)).
Limpiyakorn
Tawan
T
Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan. miketawan@yahoo.com
Kurisu
Futoshi
F
Sakamoto
Yoriko
Y
Yagi
Osami
O
D019149:Bioreactors; D004269:DNA, Bacterial / Q000235:genetics; D004586:Electrophoresis / Q000379:methods; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D009606:Nitrosomonas / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000382:microbiology*
D004269:DNA, Bacterial; D009566:Nitrates; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D012336:RNA, Ribosomal, 16S; D012722:Sewage