Magnetic carbon bead-based concentration method for SARS-CoV-2 detection in wastewater

Wastewater surveillance for pathogens is important to monitor disease trends within communities and maintain public health; thus, a quick and reliable protocol is needed to quantify pathogens present in wastewater. In this study, a method using a commercially available magnetic carbon bead-based kit, i.e., the Carbon Prep (C.prep) method (Life Magnetics), was employed to detect and quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as well as bacteriophage Phi6 and pepper mild mottle virus (PMMoV) in wastewater samples. The performance of this method was evaluated by modifying several steps and comparing it with the polyethylene glycol (PEG) precipitation method to demonstrate its applicability to virus detection in wastewater. The protocol of the C.prep method, based on the manufacturer’s instructions, could not detect SARS-CoV-2 RNA, while the optimized protocol could detect it in the tested samples at concentrations that were not significantly different from those obtained using the PEG precipitation method. However, the optimized C.prep method performed more poorly in recovering Phi6 and detecting PMMoV than the PEG precipitation method. The results of this study indicated that the full workflow of the C.prep method was not sufficient to detect the target viruses and that an additional RNA extraction step was needed to remove inhibitors in wastewater.