SURF: Announcements of Opportunity
Below are Announcements of Opportunity posted by Caltech faculty and JPL technical staff for the SURF program. Additional AOs for the Amgen Scholars program can be found here.
Specific GROWTH projects being offerred for summer 2017 can be found here.
Students pursuing opportunities at JPL must be U.S. citizens or U.S. permanent residents.
Each AO indicates whether or not it is open to non-Caltech students. If an AO is NOT open to non-Caltech students, please DO NOT contact the mentor.
Announcements of Opportunity are posted as they are received. Please check back regularly for new AO submissions! Remember: This is just one way that you can go about identifying a suitable project and/or mentor.
Announcements for external summer programs are listed here.
|Project:||Heat Inactivation of Encapsulated Bacterial Spores|
|Disciplines:||Biology/Bioengineering, Chemistry/Chemical Engineering|
Microbes that are encapsulated in solid materials such as polymers, laminates and coatings show considerably greater tolerance to heating than microbes that are on exposed surfaces. Microbes encapsulated in solid materials called the encapsulated bioburden is the critical factor in determining the length of time required for heating in the Dry Heat Microbial Reduction (DHMR) process.
Planetary Protection rules stipulate that the factor that should be employed to insure microbes are killed by a heat process is ten times longer for encapsulated microbes than for microbes that are exposed on surfaces.
Since these DHMR exposures are performed in large complex vacuum ovens that heat and cool slowly, these exposures take several days and are extremely costly to projects.
Any reduction of process time would lower costs and schedule times, thus benefiting space projects and NASA. This information generated by this research will be important for future space missions to Mars and Europa.
|Description:||The main focus of this research is to determine the time required to inactivate very heat resistant bacterial spores embedded in a polymer matrix. The decimal reduction times (D-values) of embedded spores will be measured to obtain greater confidence in the efficacy of the DHMR process. The findings of these studies will either support or refute the current DHMR exposure times specified for embedded spores. This work will explore the methods used to release the embedded spores from the polymer matrix. These approaches include cryogenic grinding and chemically dissolving the matrix. Thermal exposures will be conducted to demonstrate the spore inactivation within a solid epoxy matrix. Highly heat resistant Bacillus spores will be mixed into a binary epoxy and cast into 1.0 cubic centimeter cylinders. The cured epoxies will be exposed at the most extensively studied DHMR temperature (125C). Exposures at three to five time durations at a single temperature will be carried out to obtain lethality rates for comparison to non-embedded control spores. Many independent experiments will be completed to statistically validate the results. After temperature-exposures are completed, the solids will be cryogenically ground in a freezer mill. The resulting fine powders will be suspended into a rinse buffer, serially diluted, pipetted into petri-dishes and mixed with Tryptic Soy Agar. After incubating for three days, the number of surviving viable spores forming visible colonies will be counted, plotted and D-values will be calculated. These D-values will then be compared with D-values from non-embedded controls.|
Bauermeister, A.M., Anna Auerbach, Alexander BÃ¶ker, Niwin Flier, Christina Weber, Alexander J. Probst, Christine Moissl-Eichinger, Klaus Haberer 2014. Quantification of Encapsulated Bioburden in Spacecraft Polymer Materials by Cultivation-Dependent and Molecular Methods PLOS ONE DOI: 10.1371/journal.pone.0094265
Benardini, J.N., J. Sawyer, K. Venkateswaran, and W. L. Nicholson 2003. Spore UV and Acceleration Resistance of Endolithic Bacillus pumilus and Bacillus subtilis Isolates Obtained from Sonoran Desert Basalt:Implications for Lithopanspermia. Astrobiology 3(4):709-717
Cano, R. J. and Monica K. Borucki. 1995. Revival and Identification of Bacterial Spores in 25- to 40-Million-Year-Old Dominican Amber. Science (268):1060-1064.
Fajardo-Cavazos, P. and Wayne Nicholson. Bacillus Endospores Isolated from Granite: Close Molecular Relationships to Globally Distributed Bacillus spp. From Endolithic and Extreme Environments. Applied and environmental microbiology, 2006, 72(4):28562863
Manzanera, M. S. Vilchez, and A. Tunnacliffe. 2004. Plastic Encapsulation of Stabilized Escherichia coli and Pseudomonas putida. Applied and environmental microbiology, 70(5):31433145.
Kempf, M.J., W.W. Schubert, and R.A. Beaudet. 2008. Determination of lethality rate constants and D-values for Bacillus atrophaeus (ATCC 9372) spores exposed to dry heat from 115 degrees C to 170 degrees C. Astrobiology. 8:1169-1182.
Nicholson W.L., Munakata, N., Horneck, G., Melosh, H.J., and Setlow, P. Resistance of Bacillus endospores to extreme terrestrial and extraterrestrial environments. Microbiology and molecular biology reviews. 2000-09;64:548-72. doi:10.1128/MMBR.64.3.548-572.2000
Pflug, I.J. (1970) Dry heat destruction rates for microorganisms on open surfaces, in mated surface areas and encapsulated in solids of spacecraft hardware. In Life Sciences and Space Research VIII: Proceedings of the Open Meeting of Working Group V at the Twelfth Plenary Meeting of COSPAR, North Holland Publishing Co., Amsterdam, Netherlands, pp 131141.
Pflug, I.J. (1971) Sterilization of Space Hardware. Environmental Biology and Medicine (1971)1:63-81
Pflug, I.J., Holcomb, R.G., and Gomez, M.M. (2001) Principles of the thermal destruction of microorganisms. In Disinfection,Sterilization, and Preservation, edited by S.S. Block, Lippincott Williams and Wilkins, Philadelphia, PA, pp 79129.
Russell, A.D., Bacterial spores and chemical sporicidal agents. Clinical Microbiology Reviews 3 (2) 99-119 (1990)
Schubert, W., Beaudet, R.A. 2008, ATCC 29669 Spores Show Substantial Dry Heat Survivability, Wayne Schubert and Robert A. Beaudet Jet Propulsion Laboratory, California Institute of Technology Copyright Â© 2008 SAE International, 08ICES-0215.
Schubert, W.W., and R.A. Beaudet. Determination of Lethality Rate Constants and D-Values for Heat-Resistant Bacillus Spores ATCC 29669 Exposed to Dry Heat from 125 degrees C to 200 degrees C. Astrobiology. 11:213-223.
Setlow, P. Spores of Bacillus subtilis: their resistance to killing by radiation, heat and chemicals. Journal of Applied Microbiology 101 (3): 514-525. DOI: 10.1111/j.1365-2672.2005.02736.x
|Student Requirements:||Microbiology, Statistics, Chemistry, Biochemistry|
|Location / Safety:||Project building and/or room locations: . Student will need special safety training: Yes.|
This AO can be done under the following programs:
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