“Accumulibacter”: tales from laboratory-scale SBRsFran Slater <strong>and</strong> Phil B<strong>on</strong>dAdvanced <strong>Water</strong> Management Centre, University of Queensl<strong>and</strong>, St. Lucia, QLD 4072, Australia.The microbiology of the C<strong>and</strong>idatus “Accumulibacter phosphatis” lineage is a subject of specialinterest to many members of the <strong>IWA</strong> MEWE <str<strong>on</strong>g>Specialist</str<strong>on</strong>g> <str<strong>on</strong>g>Group</str<strong>on</strong>g>. “Accumulibacter” is a member ofthe Betaproteobacteria, well known for being a model polyphosphate accumulating organism(PAO) within enhanced biological phosphorus removal (EBPR) systems. Our knowledge of themetabolic capabilities of this intriguing lineage has increased by leaps <strong>and</strong> bounds over the pasttwenty years, through a variety of techniques, including metagenomics (García Martín et al., 2006),metatranscriptomics (He et al., 2010)<strong>and</strong> metaproteomics (Wexler et al., 2009; Wilmes et al., 2008)as well as more traditi<strong>on</strong>al methods.C<strong>on</strong>current <strong>and</strong> related studies have explored the ecology of different “Accumulibacter” cladeswithin the lineage. These studies have aimed to answer whether different clades occupy differentniches. This is interesting not <strong>on</strong>ly as a means of better underst<strong>and</strong>ing the processes that structuremicrobial communities but also, <strong>and</strong> importantly for wastewater treatment, the presence ofparticular clades might serve as a predictive tool for diagnosing EBPR system health.There is now an accumulati<strong>on</strong> of evidence that suggests that different “Accumulibacter” clades doin fact occupy different niches. Peters<strong>on</strong> <strong>and</strong> co-workers (2008) discovered several new clades of“Accumulibacter” in freshwater <strong>and</strong> estuarine sediments that have not to date been recovered fromwastewater treatment systems <strong>and</strong> dem<strong>on</strong>strated that clade distributi<strong>on</strong> was associated with habitattype rather than geographic distance. In laboratory-scale EBPR systems, we showed an associati<strong>on</strong>between, <strong>on</strong> the <strong>on</strong>e h<strong>and</strong>, Type IA “Accumulibacter” <strong>and</strong> good EBPR performance <strong>and</strong>, <strong>on</strong> theother h<strong>and</strong>, Type IIC “Accumulibacter” <strong>and</strong> the presence of glycogen-accumulating organisms(GAO) <strong>and</strong> poor EBPR performance (Slater et al., 2010).More recently, we carried out a survey of sequencing batch reactors (SBRs) operated for EBPR, <strong>and</strong><strong>on</strong>e purposefully enriched in GAO. We collected data <strong>on</strong> the influent wastewater, operati<strong>on</strong>alparameters <strong>and</strong> abundance of different “Accumulibacter” clades using terminal-restricti<strong>on</strong> lengthpolymorphism (T-RFLP) of the ppk1 gene (see Slater et al., 2010, for descripti<strong>on</strong> of the technique).Somewhat surprisingly, all the SBRs were dominated by Type IA “Accumulibacter” except for theGAO-enriched SBR (Figure 1). This was in spite of significant variati<strong>on</strong>s in terms of influentwastewater compositi<strong>on</strong> (synthetic, domestic or industrial), operati<strong>on</strong>al parameters (workingvolume, floccular or granular sludge, inclusi<strong>on</strong> of an anoxic phase etc.) <strong>and</strong> EBPR performance(aerobic P uptake between 8 <strong>and</strong> 119 mg P-PO 4 3- L -1 ).____________________________________________________________________________________________________________10<strong>IWA</strong> <str<strong>on</strong>g>Specialist</str<strong>on</strong>g> <str<strong>on</strong>g>Group</str<strong>on</strong>g> <strong>on</strong> <strong>Microbial</strong> <strong>Ecology</strong> <strong>and</strong> <strong>Water</strong> <strong>Engineering</strong>:Newsletter July 2011
Figure 1. “Accumulibacter” clade structure in different SBRs according to T-RFLP using“Accumulibacter”-specific ppk1 primers (McMah<strong>on</strong> et al., 2007) <strong>and</strong> the restricti<strong>on</strong> enzyme HaeIII.Note the dominant clade in all EBPR SBRs is TRF 218 ( ), which represents Type IA. Theremaining numbered TRFs represent known or unknown clades. Other (
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