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ID 20778
file
creator
Tsushima, Ikuo
Ogasawara, Yuji
Shimokawa, Masaki
Satoh, Hisashi
Okabe, Satoshi
NDC
Construction. Civil engineering
abstract
We investigated autotrophic anaerobic ammonium-oxidizing (anammox) biofilms for their spatial organization, community composition, and in situ activities by using molecular biological techniques combined with microelectrodes. Results of phylogenetic analysis and fluorescence in situ hybridization (FISH) revealed that ""Brocadia""-like anammox bacteria that hybridized with the Amx820 probe dominated, with 60 to 92% of total bacteria in the upper part (<1,000 ?m) of the biofilm, where high anammox activity was mainly detected with microelectrodes. The relative abundance of anammox bacteria decreased along the flow direction of the reactor. FISH results also indicated that Nitrosomonas-, Nitrosospira-, and Nitrosococcus-like aerobic ammonia-oxidizing bacteria (AOB) and Nitrospira-like nitrite-oxidizing bacteria (NOB) coexisted with anammox bacteria and accounted for 13 to 21% of total bacteria in the biofilms. Microelectrode measurements at three points along the anammox reactor revealed that the NH4+ and NO2? consumption rates decreased from 0.68 and 0.64 ?mol cm?2 h?1 at P2 (the second port, 170 mm from the inlet port) to 0.30 and 0.35 ?mol cm?2 h?1 at P3 (the third port, 205 mm from the inlet port), respectively. No anammox activity was detected at P4 (the fourth port, 240 mm from the inlet port), even though sufficient amounts of NH4+ and NO2? and a high abundance of anammox bacteria were still present. This result could be explained by the inhibitory effect of organic compounds derived from biomass decay and/or produced by anammox and coexisting bacteria in the upper parts of the biofilm and in the upstream part of the reactor. The anammox activities in the biofilm determined by microelectrodes reflected the overall reactor performance. The several groups of aerobic AOB lineages, Nitrospira-like NOB, and Betaproteobacteria coexisting in the anammox biofilm might consume a trace amount of O2 or organic compounds, which consequently established suitable microenvironments for anammox bacteria.
journal title
Applied and Environmental Microbiology
volume
Volume 73
issue
Issue 15
start page
4931
end page
4939
date of issued
2007-08
publisher
American Society for Microbiology
issn
0099-2240
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) American Society for Microbiology
relation url
department
Graduate School of Engineering