Resolving the individual contribution of key microbial populations to enhanced biological phosphorus removal with Raman\u2013FISH

Eustace Y Fernando,Per Halkjær Nielsen,Michael Wagner,Simon Jon Mcilroy,Markus C Schmid,Florian-Alexander Herbst,Jeppe Lund Nielsen,Marta Nierychlo,Francesca Petriglieri

doi:10.1038/s41396-019-0399-7

Abstract

Enhanced biological phosphorus removal (EBPR) is a globally important biotechnological process and relies on the massive accumulation of phosphate within special microorganisms. Candidatus Accumulibacter conform to the classical physiology model for polyphosphate accumulating organisms and are widely believed to be the most important player for the process in full-scale EBPR systems. However, it was impossible till now to quantify the contribution of specific microbial clades to EBPR. In this study, we have developed a new tool to directly link the identity of microbial cells to the absolute quantification of intracellular poly-P and other polymers under in situ conditions, and applied it to eight full-scale EBPR plants. Besides Ca. Accumulibacter, members of the genus Tetrasphaera were found to be important microbes for P accumulation, and in six plants they were the most important. As these Tetrasphaera cells did not exhibit the classical phenotype of poly-P accumulating microbes, our entire understanding of the microbiology of the EBPR process has to be revised. Furthermore, our new single-cell approach can now also be applied to quantify storage polymer dynamics in individual populations in situ in other ecosystems and might become a valuable tool for many environmental microbiologists.

Highlights

While the demand for phosphorus (P) is strongly increasing with the growing human population, global P reserves are limited, present in only few countries, and getting increasingly more difficult to access [1, 2]
T. elongata is one of the few known PAO that exist in pure culture and it was selected to test for qualitative and quantitative assessment of its intracellular storage polymers using Raman microspectroscopy
It should be noted that T. elongata is closely related but not identical to Tetrasphaera strains found in full-scale waste water treatment plants (WWTPs) [36]

Summary

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While the demand for phosphorus (P) is strongly increasing with the growing human population, global P reserves are limited, present in only few countries, and getting increasingly more difficult to access [1, 2].

Present address

Materials and methods

Results and discussion

Compliance with ethical standards