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bThis study determined the membrane fluidity of clostridial endospores during treatment with heat and pressure with nisin or reutericyclin. Heating (90°C) reduced laurdan (6-dodecanoyl-2-dimethylaminonaphthalene) general polarization, corresponding to membrane fluidization. Pressure (200 MPa) stabilized membrane order. Reutericyclin and nisin exhibit divergent effects on heat-and pressure-induced spore inactivation and membrane fluidity. P ressure-assisted thermal sterilization (PATS) of food is an alternative to thermal processing (1). PATS releases dipicolinic acid (DPA) from endospores, rehydrates the core of endospores, and allows for spore inactivation (2,3,4). A combination of 200 to 800 MPa with 120°C eliminates resistant spores of Clostridium botulinum (2, 5). At or above 120°C, however, pressure may fail to accelerate thermal inactivation or even exerts protective effects (2, 5). Antimicrobials acting in concert with PATS may enhance the inactivation of endospores, thus ensuring product safety at reduced treatment intensity. Nisin and reutericyclin exhibit antimicrobial activity against endospores (6, 7). Nisin is a pore-forming lantibiotic (6), reutericyclin is a proton ionophore (8). Remarkably, nisin enhances pressure-induced spore inactivation (9, 10), whereas reutericyclin had no effect or even attenuated pressure-induced inactivation of bacterial endospores (11).Endospores have multiple, distinct layers that contribute to resistance and metabolic dormancy (2, 12, 13). Dehydration of the spore core contributes to endospore resistance (12). Endospores possess an outer membrane, a remnant of sporulation, and an inner membrane separating the dehydrated core from the hydrated exterior (14, 15). Lipids of the inner membrane are compressed, and the surface area expands during germination without lipid synthesis (16). Disruption of the inner membrane of endospores rehydrates the core and allows inactivation of endospores by antimicrobials (17, 18). An improved understanding of the effect of pressure on endospore membranes will improve the control of endospores by pressure and facilitate the selection of antimicrobials to support pressure-assisted sterilization; however, little is known about the Ϫ1 nisin (B), or in the presence of 6.4 mg liter Ϫ1 reutericyclin (C). Measurements were taken every 10 min as samples were heated to 90°C at a rate of 5°C/10 min. The graph highlights the area corresponding to the CH 2 asymmetrical stretching absorbance; i and ii denote the wavenumbers corresponding to gel state and liquid-crystalline membranes, respectively. Comparable results were obtained with C. beijerinckii (data not shown).

We present an electrochemical advanced oxidation process (eAOP) reactor employing expanded graphite, potassium iodide (KI), and electrical current, which demonstrates an exceptionally high rate of inactivation of E. coli (6log reduction in viable cells) at low current density 0.6 mA/cm^2), with low contact time (5 minutes) and low concentration of KI (10 ppm). Operando X-ray fluorescence mapping is used to show the distribution of iodine species in the reactor, and operando X-ray absorption spectroscopy in the anodic chamber reveals iodine species with higher effective oxidation state than periodate. Operando electrochemical measurements confirm the conditions in the anodic chambers are favourable for the creation of highly oxidized iodine products. The killing efficiency of this new eAOP reactor far exceeds that expected from either traditional iodine-based electrochemical water treatment or advanced oxidation systems alone, a phenomenon that may be associated with the production of highly oxidized iodine species reported here.

We present an electrochemical advanced oxidation process (eAOP) reactor employing expanded graphite, potassium iodide (KI), and electrical current, which demonstrates an exceptionally high rate of inactivation of E. coli (10 6 or 6log 10 reduction in viable cells) at low current density (0.12 mA/cm 2 ), with low contact time (5 minutes) and low concentration of KI (10 ppm; 0.06 mM)). Operando X-ray fluorescence mapping is used to show the distribution of iodine species in the reactor, and operando X-ray absorption spectroscopy in the anodic chamber reveals iodine species with higher effective oxidation state than IO 4 -. Operando electrochemical measurements confirm the conditions in the anodic chambers are favourable for the creation of highly oxidized iodine products. The killing efficiency of this new eAOP reactor far exceeds that expected from either traditional iodine-based electrochemical water treatment or advanced oxidation systems alone, a phenomenon that may be associated with the production of highly oxidized iodine species reported here.