Methods for recovery of deep terrestrial subsurface sediments for microbiological studies

Abstract

Methods for the aseptic recovery of sediments from the terrestrial deep subsurface for microbiological analyses are defined. Sediments were recovered from depths > 300 m by rotary drilling techniques using bentonite drilling techniques. Four sampling tools were successfully used and compared for their ability to retrieve different types of subsurface materials. Upon retrieval, sediments were pared and processed under anaerobic conditions in a glove bag. Materials were stored under N 2 gas and shipped via overnight express to collaborating investigators. Six quality assurance protocols were incorporated to ensure that appropriate sediments were obtained and to monitor contamination from drilling fluid infringement. Two quality assurance protocols were field-applicable, and four were performed by independent laboratories. The quality assurance protocols provided multiple techniques for detecting 10 mg contamination from drilling fluids·kg −1 sediment. These techniques, which proved appropriate for different types of subsurface sediments, provided samples which were deemed acceptable for microbiological analyses.