title: High-affinity phosphate-binding protein (PBP) for phosphorous recovery: proof of concept using recombinant Escherichia 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 ionic 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.
authors.affiliation: Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI 53233, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI 53233, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Ballent
authors.affiliation: Department of Civil, Construction and Environmental Engineering, Marquette University, Milwaukee, WI 53233, USA brooke.mayer@marquette.edu.
authors.forename: Brooke K
authors.initials: BK
authors.lastname: Mayer
mesh_terms: D000327:Adsorption / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D028044:Phosphate-Binding Proteins / Q000378:metabolism*; D010758:Phosphorus / Q000737:chemistry*; D011550:Pseudomonas aeruginosa / Q000235:genetics; D062065:Wastewater / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D028044:Phosphate-Binding Proteins; D010758:Phosphorus; D062065:Wastewater; D014867:Water
keywords: Escherichia coli (E. coli); adsorption; phosphate binding protein (PBP); phosphorus; recovery; water