A procedure for removal of cyanuric acid in swimming pools using a cell-free thermostable cyanuric acid hydrolase

Feng Guo, Joseph C. McAuliffe, Cristina Bongiorni, Jacob A. Latone, Mike J. Pepsin, Marina S. Chow, Raj S. Dhaliwal, Katherine M. Hoffmann, Bill T. Brazil, Meng H. Heng, Serina L. Robinson, Lawrence P. Wackett, Gregory M. Whited

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Cyanuric acid (CYA) is used commercially for maintaining active chlorine to inactivate microbial and viral pathogens in swimming pools and hot tubs. Repeated CYA addition can cause a lack of available chlorine and adequate disinfection. Acceptable CYA levels can potentially be restored via cyanuric acid hydrolases (CAH), enzymes that hydrolyze CYA to biuret under mild conditions. Here we describe a previously unknown CAH enzyme from Pseudolabrys sp. Root1462 (CAH-PR), mined from public databases by bioinformatic analysis of potential CAH genes, which we show to be suitable in a cell-free form for industrial applications based upon favorable enzymatic and physical properties, combined with high-yield expression in aerobic cell culture. The kinetic parameters and modeled structure were similar to known CAH enzymes, but the new enzyme displayed a surprising thermal and storage stability. The new CAH enzyme was applied, following addition of inexpensive sodium sulfite, to hydrolyze CYA to biuret. At the desired endpoint, hypochlorite addition inactivated remaining enzyme and oxidized biuret to primarily dinitrogen and carbon dioxide gases. The mechanism of biuret oxidation with hypochlorite under conditions relevant to recreational pools is described.

Original languageEnglish (US)
Article numberkuab084
JournalJournal of Industrial Microbiology and Biotechnology
Issue number2
StatePublished - Mar 1 2022

Bibliographical note

Publisher Copyright:
© 2021 The Author(s) 2021. Published by Oxford University Press on behalf of Society of Industrial Microbiology and Biotechnology.


  • Biuret
  • Cyanuric acid hydrolase
  • Hypochlorite
  • Pseudolabrys
  • Water treatment

PubMed: MeSH publication types

  • Journal Article


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