The hydrocyclone- filtration extractor (HFE), now undergoing development, is a simple, robust apparatus for processing large amounts of soil to extract trace amounts of microorganisms, soluble organic compounds, and other biomarkers from soil and to concentrate the extracts in amounts sufficient to enable such traditional assays as cell culturing, deoxyribonucleic acid (DNA) analysis, and isotope analysis. Originally intended for incorporation into a suite of instruments for detecting signs of life on Mars, the HFE could also be used on Earth for similar purposes, including detecting trace amounts of biomarkers or chemical wastes in soils.
In addition to a conical separator vessel typical of a hydrocyclone, the HFE includes a pump, a sample container, an electropositive nanoparticle filter, and associated plumbing (see figure). The hydrocyclone serves to separate both cellular-sized particles (
The soil sample is prepared by mixing it with sterile water or another suitable solvent to form a slurry, which is pumped to the hydrocyclone separator vessel in tangential streams at the top (wide) end to form two concentric opposing vortices at high hydrodynamic pressures to effect separation based on particle size. The spinning motion of the injected slurry is accelerated by the conical taper, creating a large centrifugal force that causes the larger particles to rapidly separate from the rest of the flow and leave the vessel as part of underflow through the bottom (narrow) end of the separator vessel. The liquid containing suspended particles smaller than 5 μm leaves the vessel as the overflow (which is larger than the underflow) at the top (wide) end of the vessel. The overflow is then fed through the filter.
The filter contains electropositive aluminum nanotubes embedded in a glass-fiber matrix. The filter has a nominal pore size of 2 μm, but can collect biological particles having sizes down to fractions of a micron, on the basis of electrostatic charge, without clogging. The combination of the hydrocyclone and the electropositive nanoparticle filter is capable of extracting 99 percent of particles smaller than 5 μm from the soil sample and retaining them for analysis. In the prototype HFE depicted schematically in the filter, the underflow and the effluent from the filter are fed back to the sample container. It is envisioned that the fully developed HFE could operate in a continuous-flow mode, making it possible to extract biomarkers from a large volume (e.g., 1 m3) of soil using a minimal amount (e.g., 1 L) of solvent.
In a field test, the prototype HFE was made to process a slurry consisting of
4 L of sterile water mixed with 4 L of Atacama-desert soil, which contains such low concentrations of recoverable microorganisms as to be nearly impossible to analyze in the absence of an extraction-and- concentration process. After 15 minutes of recycling the slurry in the HFE, the maximum loading of the filter was reached. The filter was removed and dried and found to contain 100 g of fine particulate material, which, in turn, was removed from the filter in a laboratory for further analysis. Whereas traditional extraction protocols yielded no microbial colony-forming units, the extract from the HFE filter yielded microbes too numerous to count on standard growth plates. On the basis of development plans and this result, it is expected that cellular-extract concentrations obtained by use of the fully developed HFE will be at least 103 times those obtained by means of state-of-the art extraction methods heretofore used in environmental microbiology.
This work was done by Adrian Ponce of Caltech and Donald Obenhuber of National Research Council for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
Mail Stop 202-233
4800 Oak Grove Drive
Pasadena, CA 91109-8099
Refer to NPO-44751, volume and number of this NASA Tech Briefs issue, and the page number.
This Brief includes a Technical Support Package (TSP).
Hydrocyclone/Filter for Concentrating Biomarkers From Soil
(reference NPO-44751) is currently available for download from the TSP library.
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