Microcystin-LR Removal from Water via Enzymatic Linearization and Ultrafiltration

Abelline Fionah, Cannon Hackett, Hazim Aljewari, Laura Brady, Faisal Alqhtani, Isabel C. Escobar, Audie K. Thompson

Research output: Contribution to journalArticlepeer-review

Abstract

Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria that can bloom in freshwater supplies. This study describes a new strategy for remediation of MC-LR that combines linearization of the toxin using microcystin and e A and MlrA enzyme with rejection of linearized byproducts using membrane filtration. The MlrA enzyme was expressed in Escherichia coli (E. coli) and purified via a His-tag with 95% purity. Additionally, composite membranes made of 95% polysulfone and 5% sulfonated polyether ether ketone (SPEEK) were fabricated and used to filter a solution containing cyclic and linearized MC-LR. Tests were also performed to measure the adsorption and desorption of MC-LR on polysulfone/SPEEK membranes. Liquid chromatography-mass spectrometry (LC-MS) was used to characterize the progress of linearization and removal of MC-LR. Results indicate that the MlrA was successful at linearizing MC-LR. Membrane filtration tests showed rejection of 97% of cyclic MC-LR and virtually all linearized MC-LR, with adsorption to the membranes being the main rejection mechanism. Adsorption/desorption tests indicated that methanol could be used to strip residual MC-LR from membranes to regenerate them. This study demonstrates a novel strategy of remediation of microcystin-tainted water, combining linearization of MC-LR to a low-toxicity byproduct along with removal by membrane filtration.

Original languageEnglish
Article number231
JournalToxins
Volume14
Issue number4
DOIs
StatePublished - Apr 2022

Bibliographical note

Funding Information:
This research was funded by Grant Number P30 GM103450 from the National Institute of General Medical Sciences of the National Institutes of Health (NIH), by the National Science Foundation NSF DGE: NRT 1922694 and NSF HRD 2004710, by the Kentucky IDeA Networks of Biomedical Research Excellence (KY-INBRE) grant P20GM103436, and by by the U.S. Geological Survey under grant agreement No. G16AP00040 and administered by the Arkansas Water Resources Center.

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • enzyme
  • harmful algal blooms
  • linearization
  • microcystin
  • ultrafiltration

ASJC Scopus subject areas

  • Toxicology
  • Health, Toxicology and Mutagenesis

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