High pressure germination of Bacillus subtilis spores with alterations in levels and types of germination proteins

Authors

  • C.J. Doona,

    1. US Army-Natick Soldier RD&E Center, Warfighter Directorate, Natick, MA, USA
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    • These authors contributed equally to this work.
  • S. Ghosh,

    1. Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
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    • These authors contributed equally to this work.
  • F.F. Feeherry,

    1. US Army-Natick Soldier RD&E Center, Warfighter Directorate, Natick, MA, USA
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  • A. Ramirez-Peralta,

    1. Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
    Current affiliation:
    1. Laboratory of Biomedicine, School of Biological Sciences, Guerrero State University, México Avenida Lázaro Cárdenas, Chilpancingo, Guerrero, Mexico
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  • Y. Huang,

    1. Department of Animal and Food Sciences, University of Delaware, Newark, DE, USA
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  • H. Chen,

    1. Department of Animal and Food Sciences, University of Delaware, Newark, DE, USA
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  • P. Setlow

    Corresponding author
    1. Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
    • Correspondence

      Peter Setlow, Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT 06030-3305, USA.

      E-mail: setlow@nso2.uchc.edu

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Abstract

Aims

Examine effects of different levels and types of nutrient germinant receptors (GRs) and other germination proteins on Bacillus subtilis spore germination by a moderate high pressure (mHP) (150 megaPascals (MPa)) that triggers germination through GRs, and a very high pressure (vHP) (550 MPa) that triggers spore germination independent of GRs.

Methods and Results

The Moderate HP (mHP) and vHP germination kinetics of B. subtilis spores with large variations in levels of GRs and other germination proteins, including the GerD protein and the SpoVA proteins that comprise a spore membrane channel that is likely opened by vHP were measured.

Conclusions

GR levels were the major factor determining mHP germination rates. However, other factors modulated mHP germination rates including (i) relative levels of individual GRs (GerA, GerB, GerK), as mHP affected different GRs differently; (ii) levels of a recently identified small protein that may be a GR subunit; and (iii) a dominant negative mutation in gerD that eliminates GR-dependent nutrient germination. In contrast, the alterations in germination proteins had no major effect on vHP germination, except for reduction of SpoVA protein levels.

Significance and Impact of the Study

With the increasing use of HP for food processing, this study provides new information on factors that modulate HP germination of spores for potential application of HP technology to achieve food sterility.

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