Green and ultrafast nucleic acid extraction via sphere-mediated confinement ultrasonic grinding for sensitive foodborne pathogen detection

Nucleic acid extraction is crucial for molecular diagnostics of pathogen bacteria, however traditional extraction methods are faced with complex operation, long time and high cost. In this work, a green confinement ultrasonic grinding approach was first time reported for extracting nucleic acids from bacterial cells. Strong acoustic pressure fields were formed in numerous confined spaces using selected acrylonitrile butadiene styrene spheres under common ultrasonic cleaner due to effective transmission of ultrasound energy through these spheres and synergistic effect of multiple spheres and used to crush intact bacterial cells for release of their nucleic acids, which were directly amplified and quantified using quantitative PCR for determination of target bacteria. The common pathogenic bacteria, such as Bacillus cereus, Salmonella typhimurium and Escherichia coli O157:H7, were tested with a lysis efficiency of over 90%, and a low detection limit of 7 CFU/mL was obtained in different food samples, such as meats, milk and juices. This new nucleic acid extraction approach was featured with short time, high efficiency, low cost, no chemical and wide range, and might be applicable for various molecular diagnostic techniques in rapid detection of pathogenic bacteria.