High-affinity phosphate-binding protein (PBP) for phosphorous recovery: proof of concept using recombinantEscherichia coli

Abstract

Phosphorus (P) is a critical, non-renewable nutrient; yet excess discharges can lead to eutrophication and deterioration of water quality. Thus, P removal from water must be coupled with P recovery to achieve sustainable P management. P-specific proteins provide a novel, promising approach to recover P from water. Bacterial phosphate-binding proteins (PBPs) are able to effectively remove phosphate, achieving extremely low levels in water (i.e. 0.015 mg-P L −1 ). A prerequisite of using PBP for P recovery, however, is not only removal, but also controlled P release, which has not yet been reported.Phosphate release using recombinant PBP-expressing Escherichia coli was explored in this study. Escherichia coli was genetically modified to overexpress PBP in the periplasmic space. The impacts of NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Letters, Vol. 363, No. 20 (October 2016). DOI. This article is © Oxford University Press and permission has been granted for this version to appear in e-Publications@Marquette. Oxford University Press does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Oxford University Press. FEMS Microbiology 2ionic strength, temperature and pH on phosphate release were assessed. PBP-expressed E. coli demonstrated consistently superior ability to adsorb more phosphate from liquid and release more phosphate under controlled conditions relative to negative controls (unexpressed PBP E. coli and E. coli K12). Lower pH (3.8), higher temperature (35ºC) and higher ionic strength (100 mM KCl) facilitated increased phosphate release, providing a maximum of 2.1% P recovery within 3 h. This study provides proof of concept of the feasibility of using PBP to recover P.

Phosphate removal and recovery using immobilized phosphate binding proteins

“…The Pst protein complex comprises four subunits, an ATP-binding protein (pstB), two transmembrane proteins (pstA and pstC), and a periplasmic PBP (pstS) (Luecke and Quiocho, 1990; Santos-Beneit et al., 2008). The periplasmic pstS PBP has recently attracted interest as a potential high-affinity, phosphate-specific P i adsorbent (Kuroda et al., 2000; Li et al., 2009; Yang et al., 2016, 2017).…”

“…Removal of P i to ultra-low concentrations has been demonstrated using PBP expressed in bacterial cells' periplasmic space, expressed on the cells' surface, or immobilized on Sepharose beads (Choi et al., 2013; Kuroda et al., 2000; Li et al., 2009; Yang et al., 2016). For example, Choi et al.…”

“…To better support the circular phosphorus economy via the waste-to-resource paradigm, recovery of the captured P i is essential. To assess P i recovery, Yang et al. (2016) investigated the effect of varying temperature, pH, and ionic strength on P i release from PBP over-expressed in the periplasmic space of E. coli cells.…”

“…(2016) investigated the effect of varying temperature, pH, and ionic strength on P i release from PBP over-expressed in the periplasmic space of E. coli cells. However, a maximum of only 1.4–2% of the adsorbed P i was recovered after exposing the recombinant E. coli cells to low pH (pH 3.8), high temperature (35 °C), or high ionic strength (100 mM KCl) for 3 h (Yang et al., 2016). On the other hand, Kuroda et al.…”

Biological Phosphorus Recovery: Review of Current Progress and Future Needs

“…It is also possible that biological removal mechanisms such as precipitation (as described for BES in Section 5.2.1 the ''Bioelectrochemical'' Systems section) and adsorption can be leveraged to enhance phosphorus recovery. One example of a biological system in the early stages of research uses the phosphorus-binding potential of the high-affinity phosphatebinding protein (PBP or PstS) to biosorb phosphate (Choi et al, 2013;Yang et al, 2016). The primary advantage of phosphorus biosorption is that the phosphorus is not integrated into the biomass, but is instead very selectively separated from complex aquatic matrices.…”