Wayne L. Nicholson

Professor

Department of Microbiology and Cell Science University of Florida Space Life Sciences Laboratory, Kennedy Spcae Center, FL  
Ph.D. (1987) University of Wisconsin-Madison
Postdoctoral (1987-1990) University of Connecticut Health Center

Description of Research

Mechanisms of bacterial spore resistance and longevity.

 Bacterial endospores are the longest-lived cells known, and exhibit a high degree of resistance to extremes of temperature, desiccation, pressure, and radiation over extended time periods.  Spore DNA is a major target lethal and mutagenic damage, and research in our lab concentrates on mechanisms that protect spore DNA from damage and by which DNA damage is repaired during spore germination, using the model organism Bacillus subtilis. Understanding spore resistance has important applications in a variety of fields ranging from public health and bioterrorism to geomicrobiology and astrobiology.

Survival and proliferation of microorganisms in extreme extraterrestrial environments.

 A portion of the spore resistance and longevity research in our lab is concentrated on placing physical constraints on lithopanspermia theory, which postulates the transfer of viable microorganisms between planets as the result of natural impact processes. Such research has important implications in the fields of astrobiology and in planetary protection research.

Microbial evolution in novel environments.

We have been conducting laboratory-scale evolution experiments of B. subtilis cells cultivated for thousands of generations in the presence or absence of strong selective pressure for sporulation. We have uncovered a number of interesting processes which occur during bacterial evolution.  We have isolated a number of spontaneous mutations in the RNA polymerase beta subunit that cause global changes in B. subtilis cell physiology and transcription. Our current plans are to extend these studies to microbial evolution in the space environment.

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Selected Publications

Nicholson, W.L. and A.C. Schuerger.  2005. Survival and germinability of Bacillus subtilis spores after incubation at Mars atmospheric pressure: implications for planetary protection and lithopanspermia. Astrobiology 5(4): 536-544.

Fajardo-Cavazos, P., R. Rebeil, and W.L. Nicholson. 2005. Essential cysteine residues in Bacillus subtilis spore photoproduct lyase identified by alanine scanning mutagenesis. Curr. Microbiol. 51: 331-335.

Fajardo-Cavazos, P., L. Link, H.J. Melosh, and W.L. Nicholson. 2005. Bacillus subtilis spores on artificial meteorites survive hypervelocity atmospheric entry: implications for lithopanspermia. Astrobiology 5(6): 726-736.

Nicholson, W.L., A.C. Schuerger, and P. Setlow . 2005. The solar UV environment and bacterial spore UV resistance: considerations for Earth-to-Mars transport by natural processes and human spaceflight. Mutat. Res. Mutat. Res. 571: 249-264.

Nicholson, W.L. 2004. Ubiquity, longevity, and ecological roles of Bacillus spores, p. 1-15, in "Bacterial Spore Formers: Probiotics and Emerging Applications", E. Ricca, A.O. Henriques, and S.M. Cutting (eds.), Horizon Scientific Press, Norfolk, UK.

Maughan, H. and W.L. Nicholson. 2004. Stochastic processes influence stationary-phase decisions in Bacillus subtilis.  J. Bacteriol. 186: 2212-2214.

Maughan, H., B. Galeano, and W.L. Nicholson. 2004. Novel rpoB mutations conferring rifampicin resistance on Bacillus subtilis: global effects on growth, competence, sporulation, and germination.J. Bacteriol. 186: 2481-2486.

Link, L., J. Sawyer, K. Venkateswaran, and W.L. Nicholson. 2004. Extreme spore UV resistance of Bacillus pumilus isolates obtained from an ultra-clean Spacecraft Assembly Facility. Microbial Ecology Microb. Ecol. 47: 159-163.

Benardini,  J. N., J. Sawyer, K. Venkateswaran, and W.L. Nicholson.  2004.  Spore UV and acceleration resistance of endolithic Bacillus pumilus and B. subtilis isolates obtained from Sonoran desert basalt: implications for lithopanspermia. Astrobiology Astrobiology 3:709-717.

Nicholson, W.L. 2003. Using Thermal Inactivation Kinetics to Calculate the Probability of Extreme Spore Longevity: Implications for Paleomicrobiology and Lithopanspermia. Orig. Life Evol. Biosphere 33: 621-631.     

La Duc, M. T., W. Nicholson, R. Kern, and K. Venkateswaran. 2003. Microbial characterization of the Mars Odyssey spacecraft and its encapsulation facility. Environ. Microbiol. 5: 977-985.

Galeano, B., E. Korff, and W.L. Nicholson. 2003. Inactivation of Vegetative Cells, but Not Spores, of Bacillus anthracis, B. cereus, and B. subtilis on Stainless Steel Surfaces Coated with an Antimicrobial Silver- and Zinc-Containing Zeolite Formulation.  Appl. Envir. Microbiol. 69: 4329-4331.

Nicholson, W.L. and B. Galeano. 2003. UV Resistance of Bacillus anthracis Spores Revisited: Validation of Bacillus subtilis Spores as UV Surrogates for Spores of B. anthracis Sterne.   Appl. Envir. Microbiol. 69: 1327-1330.

Marshall, M.M., S. Hayes, J. Moffett, C.R. Sterling, and W.L. Nicholson. 2003. Comparison of UV Inactivation of Spores of Three Encephalitozoon Species with That of Spores of Two DNA Repair-Deficient Bacillus subtilis Biodosimetry Strains. Appl. Envir. Microbiol. 69: 683-685.

Nicholson, W.L., B. Setlow, and P. Setlow. 2002. UV photochemistry of DNA in vitro and in Bacillus subtilis spores at Earth-ambient and low atmospheric pressure: implications for spore survival on other planets or moons in the solar system. Astrobiology 2: 417-427.

Nicholson, W.L. 2002. Roles of Bacillus endospores in the environment. Cell. Molec. Life Sci. 59: 410-416.

Nicholson, W.L. and H. Maughan. 2002. The spectrum of spontaneous rifampin resistance mutations in the rpoB gene of Bacillus subtilis 168 spores differs from that of vegetative cells and resembles that of Mycobacterium tuberculosis. J. Bacteriol. 184: 4936-4940.

Slieman, T. A. and W. L. Nicholson 2001. Role of dipicolinic acid in survival of Bacillus subtilis spores exposed to artificial and solar UV radiation. Appl. Environ. Microbiol. 67: 1274-1279.

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