Rapid detection of Cyanobacteria by recombinase polymerase amplification combined with lateral flow strips

Abstract

Cyanobacteria are one of the major groups of algae causing algal blooms. In this study, we developed a rapid method for detecting Cyanobacteria using a recombinase polymerase amplification (RPA) method coupled with lateral flow (LF) strips. After releasing cyanobacterial DNA from cells using a freeze-cracking method, DNA was amplified using the RPA method. Next, the RPA products were detected using the LF test. LF-RPA successfully amplified the DNA of eight cyanobacterial species and detected their presence in the sample with high specificity, distinguishing them from five non-cyanobacterial species. The method could detect cyanobacterial DNA in water samples containing as low as 0.01 cell/mL Cyanobacteria, making the method more sensitive than polymerase chain reaction (PCR), which required cell densities of at least 104 cell/mL. LF-RPA could amplify and detect cyanobacterial DNA at any temperature in the range 30–45 C in just 30 min and without the need for a thermal cycler. The method developed in this study is simple, rapid, and effective for on-site testing of Cyanobacteria, which may become a routine measurement in efforts to detect and treat harmful algal blooms.