In this paper, an original nonthermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a one minute treatment. A major requirement for the effectiveness of the process resided in the highly dehydrated state of the spores. Only a water activity below 0.3 led to substantial inactivation. The solubility of the gas in the lipid components of the spore and its diffusion properties was essential to inactivation. The main phenomenon involved seems to be the sorption of the gas under pressure by the spores' structures such as residual pores and plasma membranes, followed by a sudden drop in pressure. Observation by phase-contrast microscopy suggest that internal structures have been affected by the treatment. Some parallels with polymer permeability to gas and rigidity at various water activities offer a few clues about the behavior of the outer layers of spores in response to this parameter and provide a good explanation for the sensitivity of spores to high gas pressure discharge at low hydration levels. Specificity of microorganisms such as size, organization and composition could help in understanding the differences between spores and yeast regarding the parameters required for inactivation, such as pressure or maintenance time. Biotechnol. Bioeng.
Rapid and specific characterization of bacterial endospores is dependent on the ability to rupture the cell wall to enable analysis of the intracellular components. In particular, bacterial spores from the bacillus genus are inherently robust and very difficult to lyze or solubilize. Standard pro...
Implantable polymers, as used for biomedical applications, inherently have to be sterile. Nonetheless, most implants, particularly those comprised of biomaterials developed in recent years for tissue engineering, are heat sensitive. Therefore, use of hazardous (radio)chemicals"due to lack of alte...
The combined pressure-thermal-pH influence on inactivation of Bacillus subtilis ATCC 6633 spores (1 o- 108 cfu/mL initial count) in citrate-phosphate buffer was studied over a range of pressure (690 and 827 MPa), process temperature (60, 65, 70 and 75C), pH (3, 5 and 7) and pressure-holding time ...
Clostridium perfringens type A isolates carrying a chromosomal gene for enterotoxin production (chromosomal c. perfringens enterotoxin [C-cpe]strains) are frequent causative agents of food poisoning. Predictive models for their growth in meat products have been published; however, the development...
Pressure-assisted thermal processing (PATP) at T < 100°C can be used when enzyme inactivation and pasteurization by high pressure processing (HPP) is not feasible due to long processing times while PATP at T > 100°C can be used when bacterial spores inactivation is necessary. In PATP,...
High-pressure thermal sterilization (HPTS) is an emerging technology to produce shelf stable low acid foods. Pressures below 300 MPa can induce spore germination by triggering germination receptors. Pressures above 500 MPa could directly induce a Ca+2-dipicolinic acid (DPA) release, which trigger...
The current work describes a novel technique by which certain types of polymers subjected to dry gaseous ozone acquire the ability to inactivate microorganisms, including those as resistant as bacterial spores. The originality and advantages of this ozone treatment of polymer surfaces rest on its...
The food-processing industry has made large investments in processing facilities relying mostly on conventional thermal processing technologies with well-established reliability and efficacy. Replacing them with one of the novel alternatives recently developed is a decision that must be carefully...
High-pressure carbon dioxide (HPCD) treatment is currently considered as an attractive non-thermal process for preserving food. Since the first level of interaction between HPCD and the bacterial cells is lowering of the pH, knowledge of the pH of a food product in contact with CO2 at high-pressu...
A method and a microfluidic device for automated extraction and purification of nucleic acids from biological samples have been developed. The method involves disruption of bacterial cells and/or viral particles by combining enzymatic and chemical lysis procedures followed by solid-phase sorbent ...
