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Bacterial responses to modeled reduced gravity conditions

Vukanti, Raja Venkata Narayana Rao
http://rave.ohiolink.edu/etdc/view?acc_num=kent1240259731

Abstract Details

2009, PHD, Kent State University, College of Arts and Sciences / School of Biomedical Sciences.
Relatively few studies have examined bacterial responses to the reduced gravity (RG) conditions that are experienced by bacteria grown in orbit in space vessels, such as International Space Station. Because of limited access to space conditions, clinorotation is utilized to model certain aspects of RG conditions such as lack of sedimentation, low shear, and low turbulence (here referred to as modeled reduced gravity [MRG] conditions). RG conditions, either actual or modeled, alter a wide variety of bacterial parameters such as growth, resistance to multiple stresses, and virulence. While, a few studies have speculated that conditions of MRG act as a direct signal thus eliciting some of these bacterial responses, some studies have speculated that extra-cellular changes (such as accumulation of toxic by-products and/or reduced availability of nutrients) that are indirectly altered by these conditions might account for the changes in bacterial behavior. The overarching hypothesis for this study is that bacterial responses to MRG conditions vary with availability of nutrients that are indirectly altered by these environmental conditions. Observations made to test the hypothesis were based on changes in expression of whole genome and of specific genes in Escherichia coli grown under MRG as compared to normal gravity (NG) controls. In addition, E. coli and Staphylococcus aureus starvation-related physiological responses were examined under nutrient-rich and -poor conditions and at both exponential and stationary phases of growth. E. coli whole genome expression patterns revealed the simultaneous expression of starvation inducible genes and genes associated with multiple stress responses. Subsequent gene expression studies showed that increased expression of multiple stress response genes under MRG occurs only during the latter stages of growth in rich medium and resembles the general stress response. Examination of E. coli and S. aureus physiology suggested that bacteria become physiologically more active and more viable under MRG conditions as compared to NG conditions, however, these responses vary with growth media and growth phase. Overall, my data suggests that bacterial responses to MRG are due to changes in the microenvironment around the bacteria, such as reduced availability of nutrients, that are indirectly altered, rather than by direct gravitational effects.
Laura G. Leff, PhD (Committee Chair)
Christopher J. Woolverton, PhD (Committee Member)
Eric M. Mintz, PhD (Committee Member)
Michael J. Tubergen, PhD (Committee Member)
Donald F. Palmer, PhD (Committee Member)
214 p.
Microbiology
Bacteria; modeled reduced gravity; response; gene expression; physiology

Recommended Citations

Citations

  • Vukanti, R. V. N. R. (2009). Bacterial responses to modeled reduced gravity conditions [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1240259731

    APA Style (7th edition)

  • Vukanti, Raja Venkata Narayana Rao. Bacterial responses to modeled reduced gravity conditions. 2009. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1240259731.

    MLA Style (8th edition)

  • Vukanti, Raja Venkata Narayana Rao. "Bacterial responses to modeled reduced gravity conditions." Doctoral dissertation, Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1240259731

    Chicago Manual of Style (17th edition)

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© 2009, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.