Comparison between Direct Microscopy and Flow Cytometry for rRNA-Based Quantification of Candidatus Accumulibacter phosphatis in Activated Sludge
Abstract:A comparison of the quantification of a specific microbial group in activated sludge by fluorescent in-situ hybridization, coupled with either direct microscopic counting or flow cytometry, was performed using an enhanced-biological-phosphorus-removal, sequencing-batch reactor. The population dynamics of Candidatus Accumulibacter phosphatis ( Cand. A. phosphatis) was evaluated during two separate runs of the reactor. With the operational conditions used, Cand. A. phosphatis was enriched until a failure in the pH controller eliminated its ecological advantage. As a result, the comparison of quantification techniques included Cand. A. phosphatis concentrations as low as 11% and as high as 96% of the total cells in the samples. The analysis demonstrated that, regardless of the particular limitations of each technique, both provided similar results when the activated-sludge flocs were easily dispersed. However, when the activated-sludge samples contained flocs that were difficult to disperse, flow cytometry failed to provide quantitative results.
Document Type: Research Article
Publication date: 2006-02-01
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Water Environment Research� (WER�) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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