In situ characterization of nitrifiers in an activated sludge plant: detection of Nitrobacter Spp.
OBJECTIVE
The purpose of this work was to investigate microbial ecology of nitrifiers at the genus level in a typical full-scale activated sludge plant.


RESULTS
Grab samples of mixed liquor were collected from a plug-flow reactor receiving domestic wastewater. Fluorescent in situ hybridization technique (FISH) was used to characterize both ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in combination with Confocal Scanning Laser Microscope (CSLM). Fluorescently labelled, 16S rRNA-targeted oligonucleotide probes were used in this study. Both Nitrosomonas and Nitrosospira genera as AOB and Nitrobacter and Nitrospira genera as NOB were sought with genus specific probes Nsm156, Nsv443 and NIT3 and NSR1156, respectively.


CONCLUSIONS
It was shown that Nitrosospira genus was dominant in the activated sludge system studied, although Nitrosomonas is usually assumed to be the dominant genus. At the same time, Nitrobacter genus was detected in activated sludge samples.


CONCLUSIONS
Previous studies based on laboratory scale pilot plants employing synthetic wastewater suggested that only Nitrospira are found in wastewater treatment plants. We have shown that Nitrobacter genus might also be present. We think that these kinds of studies may not give a valid indication of the microbial diversity of the real full-scale plants fed with domestic wastewater.
Coskuner
G
G
Cumhuriyet Universitesi, Cevre Muhendisligi Bolumu, Sivas, Turkey. drcoskuner@yahoo.com
Curtis
T P
TP
D000641:Ammonia / Q000378:metabolism; D020562:Betaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017753:Ecosystem; D017404:In Situ Hybridization, Fluorescence; D018613:Microscopy, Confocal; D009573:Nitrites / Q000378:metabolism*; D009576:Nitrobacter / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D015345:Oligonucleotide Probes; D010084:Oxidation-Reduction; D012722:Sewage / Q000382:microbiology*; D013045:Species Specificity
D009573:Nitrites; D015345:Oligonucleotide Probes; D012722:Sewage; D000641:Ammonia; D009584:Nitrogen