Comment on 'Gould polyphosphate-accumulating organisms (PAOs) be glycogen-accumulating organisms (GAOs)?' by Zhou, Y., Pijuan, M., Zeng, R., Lu, Huabing and Yuan Z. Water Res. (2008) doi:10.1016/j.waterres.2008.01.003

摘要

Polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) are metabolically closely related bacteria. Both can accumulate substrates (fatty acids) under anaerobic conditions as poly-β-hydroxyalkanoates (PHAs). GAOs obtain their energy from ATP generation from the conversion of glycogen to PHA through glycolysis, while PAOs obtain their energy from glycolysis and polyphosphate (Poly-P) degradation. The question of whether PAOs can still maintain their activity after Poly-P is depleted is therefore highly relevant. In a very interesting paper, Zhou et al. (2008) observed that under Poly-P limiting conditions PAOs are able to behave as GAOs. However, in a very similar study, Brdjanovic et al. (1998a) concluded the opposite, stating that PAOs are not able to take up HAc under anaerobic conditions when their intracellular Poly-P is depleted. The purpose of this discussion is to provide some hypotheses and certain explanations for the discrepancies observed between both studies.