Effects of High-Pressure Treatment on Spores of Clostridium Species.
This work analyzes the high-pressure (HP) germination of spores of the food-borne pathogen Clostridium perfringens (with inner membrane [IM] germinant receptors [GRs]) and the opportunistic pathogen Clostridium difficile (with no IM GRs), which has growing implications as an emerging food safety threat. In contrast to those of spores of Bacillus species, mechanisms of HP germination of clostridial spores have not been well studied. HP treatments trigger Bacillus spore germination through spores' IM GRs at ∼150 MPa or through SpoVA channels for release of spores' dipicolinic acid (DPA) at ≥400 MPa, and DPA-less spores have lower wet heat resistance than dormant spores. We found that C. difficile spores exhibited no germination events upon 150-MPa treatment and were not heat sensitized. In contrast, 150-MPa-treated unactivated C. perfringens spores released DPA and became heat sensitive, although most spores did not complete germination by fully rehydrating the spore core, but this treatment of heat-activated spores led to almost complete germination and greater heat sensitization. Spores of both clostridial organisms released DPA during 550-MPa treatment, but C. difficile spores did not complete germination and remained heat resistant. Heat-activated 550-MPa-HP-treated C. perfringens spores germinated almost completely and became heat sensitive. However, unactivated 550-MPa-treated C. perfringens spores did not germinate completely and were less heat sensitive than spores that completed germination. Since C. difficile and C. perfringens spores use different mechanisms for sensing germinants, our results may allow refinement of HP methods for their inactivation in foods and other applications and may guide the development of commercially sterile low-acid foods.



Spores of various clostridial organisms cause human disease, sometimes due to food contamination by spores. Because of these spores' resistance to normal decontamination regimens, there is continued interest in ways to kill spores without compromising food quality. High hydrostatic pressure (HP) under appropriate conditions can inactivate bacterial spores. With growing use of HP for food pasteurization, advancement of HP for commercial production of sterile low-acid foods requires understanding of mechanisms of spores' interactions with HP. While much is known about HP germination and inactivation of spores of Bacillus species, how HP germinates and inactivates clostridial spores is less well understood. In this work we have tried to remedy this information deficit by examining germination of spores of Clostridium difficile and Clostridium perfringens by several HP and temperature levels. The results may give insight that could facilitate more efficient methods for spore eradication in food sterilization or pasteurization, biodecontamination, and health care.
U.S. Army Natick Soldier RD&E Center, Warfighter Directorate, Natick, Massachusetts, USA.
Christopher J
CJ
Doona
U.S. Army Natick Soldier RD&E Center, Warfighter Directorate, Natick, Massachusetts, USA.
Florence E
FE
Feeherry
Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA.
Barbara
B
Setlow
Department of Physics, East Carolina University, Greenville, North Carolina, USA.
Shiwei
S
Wang
Department of Physics, East Carolina University, Greenville, North Carolina, USA.
William
W
Li
Department of Oral Health and Diagnostic Science, UConn Health, Farmington, Connecticut, USA.
Frank C
FC
Nichols
Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon, USA.
Prabhat K
PK
Talukdar
Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon, USA.
Mahfuzur R
MR
Sarker
Department of Physics, East Carolina University, Greenville, North Carolina, USA.
Yong-Qing
YQ
Li
Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA.
Aimee
A
Shen
Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA setlow@nso2.uchc.edu.
Peter
P
Setlow
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003013:Clostridium / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D004203:Disinfection / Q000379:methods*; D011312:Pressure; D013171:Spores, Bacterial / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D013696:Temperature
D001426:Bacterial Proteins