Nanoprobes for Quantification of Ammonia-oxidizing Bacteria (AOB) in the Biofilm and Suspended Growth Biomass of the Full- and Partial-bed Biological Aerated Filters

Fatihah Suja'
School of Civil and Structural Engineering, Engineering Faculty, Universiti Kebangsaan Malaysia 43600 Bangi Selangor Malaysi

Donnelly Tom
School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, NE1 7RU United Kingdom

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     Last modified: February 13, 2006

Abstract
The extent of comparable nitrogen removal in the full- and partial-bed biological aerated reactors needs further microbiological evidence, specifically that of the existence of Ammonia-oxidizing Bacteria (AOB). The nitrogen removal process in such systems is typically initiated by chemoliautotrophic ammonia-oxidizing bacteria converting ammonia to nitrite and traces of oxidized nitrogen gases. To detect the AOB in the samples, the Fluorescent in situ hybridization (FISH) technique was applied in order to produce the fluorescent sites in the cells, and these were detected through the use of confocal scanning laser microscopy (CSLM). The steps involved fixation of the samples, permeabilization and hybridization with nanoprobes, and finally detection with confocal laser scanning microscope (CLSM). The formation of a dense biofilm as a result of higher turbulence would account for the higher number of AOB cells enumerated in the biofilm samples from the partial-bed reactor (4.259 x 105 ±1.881 x 105 no of AOB cells/ml sample) as compared to those from the full-bed reactor (1.523 x 105 ±7.979 x 104 no of AOB cells/ml sample).