Robotic Nucleic Acid Isolation Using a Magnetic Bead Resin and an Automated Liquid Handler for Biological Agent Simulants

Abstract

The events that occurred following the mailing of Bacillus anthracis-laced envelopes through the postal system has highlighted the need to perform biological screening on large numbers of environmental samples. High-throughput screening that relies on integrated robotic systems to speed analysis has been undertaken to handle the surge in samples requiring testing in events involving weapons of mass destruction. These automated screening systems require DNA extraction methods capable of handling environmental samples that contain inhibitors and have target organisms at low concentrations. This study describes the development of a method for the detection of the biological warfare agent simulants Erwinia herbicola and Bacillus subtilis var. niger spores using paramagnetic bead-based resin with an automated liquid handler and environmental samples.

Evaluation of the Cepheid GeneXpertR system for detecting Bacillus anthracis

“…A concern with implementing automated systems that extract nucleic acid is the potential for cross‐contamination of negative samples as a result of aerosolization or robotic error (Bailey et al. 2003; Knepp et al.…”

“…A decrease in preparation time is obtained, manual labour is reduced and human error, such as pipetting discrepancies and sample exchange, is eliminated (Smit et al 2000). Integrated platforms must include an effective method for sample processing, incorporating an efficient lysis mechanism to purify nucleic acid as well as steps to remove inhibitors, in addition to containing stable PCR reagents that can accommodate the direct transfer of nucleic acid into the reaction (Petersen and McMillan 2002;Bailey et al 2003).…”

“…Exact spore counts were not necessary, as the evaluation of these two platforms was designed to show the benefit of using an integrated system capable of sample preparation and real-time PCR analysis over direct PCR analysis of a raw sample. A concern with implementing automated systems that extract nucleic acid is the potential for cross-contamination of negative samples as a result of aerosolization or robotic error (Bailey et al 2003;Knepp et al 2003). All liquid handling by the GeneXpertÒ, for both sample preparation and amplification, occurs within the disposable cartridge, which prevents fluid cross-contamination.…”