Multicultural Metabolic Map

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Science  20 Oct 2006:
Vol. 314, Issue 5798, pp. 387
DOI: 10.1126/science.314.5798.387c

The microbe-based treatment of wastewater has never been a glamorous topic of conversation, and efforts at improving the efficiency of solute removal have largely been empirical in approach. Furthermore, the population of microbes may, at times, fluctuate unpredictably, which can result in the collapse of the entire community. García Martín et al. attempt to define the genomic composition of the candidate species, referred to as Accumulibacter phosphatis, that acquires inorganic phosphate, sequesters it as polyphosphate, and then conveniently sinks to the bottom of the treatment tank. From two lab-scale samples of sludge (derived from wastewater plants in Wisconsin, USA, and Brisbane, Australia), they obtained enough sequence to estimate the genome size of A. phosphatis as 5.6 Mb, with a high degree of sequence identity between the two samples. The list of genes is consistent with an aerobic buildup of polyphosphate, which is then used as an energy source for the anaerobic caching of volatile organic acids as polyhydroxyalkanoates. An unexpected (inferred) capacity for nitrogen fixation and a parcel of cobalamin-dependent enzymes suggest that A. phosphatis might thrive in an environment supplemented with cobalt and low in fixed nitrogen. — GJC

Nat. Biotechnol. 24, 1263 (2006).

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