An investigation of SARS-CoV-2 RNA concentration methods using pH variations for higher recovery rates in wastewater testing
Liane Geis, Robert Delatolla, Frances Pick
Department of Earth and Environmental Sciences, University of Ottawa
Liane Geis, Robert Delatolla, Frances Pick
Department of Earth and Environmental Sciences, University of Ottawa
Since December 2019, the world has been affected by the COVID-19 global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Detectability of SARS-CoV-2 RNA in feces has been extensively reported and wastewater streams are presently being used to monitor COVID-19. However, methods for concentration and analyses have not been standardized. This study investigated an additional concentration method to simple centrifugation by testing samples at three different pH levels to determine if pH alters RNA recovery rates. The hypothesis is that low pH levels favours recovery of extracted viral RNA from wastewater samples. The study was conducted on primary sludge and influent samples and consisted of three replicates for each pH level (2.5, 3.5 and an unmodified reference pH) for each sample type. Results from RT-qPCR and statistical analyses found that variations between pH levels were significant, with higher recovery values observed at the lowest pH level, therefore concluding that recovery rates of viral genes increase as pH decreases. The additional concentration method by acidification before centrifugation may be suitable for continuous use as it doesn’t require much more labor and can be done in a timely manner. Due to the limited sample size of this study, further research with a larger sample size taken from multiple days is needed to assess the credibility and generalizability of the results.