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Escherichia coli O157:H7 is a notorious foodborne pathogen known to cause severe illnesses such as hemolytic colitis and hemolytic uremic syndrome, with fresh produce consumption being implicated in recent outbreaks. The inappropriate use of antimicrobials to combat pathogens has led to the emergence and rapid dissemination of antimicrobial-resistant microorganisms including pathogenic E. coli , presenting a significant risk to humans. Here, we isolated two E. coli O157:H7 infecting bacteriophages, PECP14 and PECP20, from irrigation water and city sewage, respectively, as alternatives to antimicrobials. Both phages were stable for at least 16 h in a broad range of pH (pH 3–11) and temperature (4–40 °C) conditions and have a double-stranded DNA chromosome. PECP14 and PECP20, classified under the Epseptimavirus and Mosigvirus genera, respectively, exhibit specificity in targeting different host receptors, BtuB protein and lipopolysaccharide. Interestingly, these phages demonstrate the ability to infect not only E. coli O157:H7 but also other foodborne enteric pathogens like Shigella sonnei and S. flexneri. Upon mixing phages with their respective host bacteria, rapid adsorption (at least 68 % adsorption within 10 min) and substantial bacterial lysis were observed. The efficacy of phage treatment was further validated through the reduction of E. coli O157:H7 on radish sprouts. Moreover, purified endolysins, LysPECP14 and LysPECP20, derived from each phage exhibited remarkable bacteriolytic activity against E. coli O157:H7 cells pretreated with EDTA. In particular, the activity of LysPECP20 was also noticeable against Listeria monocytogenes and Bacillus cereus , suggesting its potential for broader antimicrobial applications in food industry. The combined results showed that the phages PECP14, PECP20, and their endolysins could be used for biological control of E. coli O157:H7 in various circumstances, from production, harvesting, and storage stages to processing and distribution steps of agricultural products. • New lytic bacteriophages PECP14 and PECP20 were isolated from environmental samples. • Both infect and lyse various strains of EHEC serotype O157:H7 and some other enteric pathogens. • No harmful genes were present in the genomes of PECP14 and PECP20. • The phages exhibited substantial antimicrobial activity against E. coli O157:H7 in radish sprouts. • Derived endolysins were also effective in controlling E. coli O157:H7 and some foodborne pathogens. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the antimicrobial activities of gaseous essential oils (EO gases) against Listeria monocytogenes on the surfaces of a laboratory medium and radish sprouts. We determined the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) values of EO gases from eight EOs extracted from basil leaves, carrot seed, cinnamon bark, cinnamon leaves, clove flower buds, oregano leaves, thyme flowers (linalool), and thyme leaves (thymol) against L . monocytogenes on a nutrient agar supplemented with 1% glucose and 0.025% bromocresol purple (NGBA). Oregano, thyme thymol, and cinnamon bark EO gases showed the strongest antilisterial activities (MIC and MLC, 78.1 μL/L). We also investigated the inhibitory and lethal activities of these gases against L . monocytogenes on the surface of radish sprouts. The number of L . monocytogenes after exposure to EO gases at ≥ 156 μL/L was significantly ( P ≤ 0.05) lower than that of untreated L . monocytogenes . For example, the initial number of L . monocytogenes on the surface of radish sprouts (ca. 6.3 log CFU/g) decreased by 1.4 log CFU/g within 24 h at 30 °C and 43% relative humidity (RH) without EO gas treatment, whereas the number of L . monocytogenes after exposure to oregano, thyme thymol, and cinnamon bark EO gases at 156 μL/L decreased by 2.1, 2.1, and 1.8 log CFU/g, respectively, after 24 h. Although EO gases exerted greater lethal activities at higher concentrations (312 and 625 μL/L), L . monocytogenes on the surface of radish sprouts was not completely inactivated. The number of L . monocytogenes on sprouts treated with oregano, thyme thymol, and cinnamon bark EO gases at 625 μL/L decreased by 2.7–3.0 log CFU/g after 24 h at 30 °C and 43% RH. Results indicate that EO gases that showed antilisterial activities on a laboratory medium also exhibited reduced lethal activity on the surface of radish sprouts. These findings will be useful when developing strategies to inactivate L . monocytogenes and possibly other foodborne pathogens on sprouts and perhaps other foods using EO gases. [ABSTRACT FROM AUTHOR]

This study investigated the effects of cold plasma treatment (CPT) on the inhibition of Salmonella typhimurium on radish sprouts and the quality attributes of the sprouts. Radish sprouts were treated with nitrogen (N 2 )-cold plasma at 900 W and 667 Pa for 0, 2, 5, 10, and 20 min using a microwave-powered CPT system. The sensory attributes of the radish sprouts, appearance and odor, were evaluated before and after the treatment. The effects of N 2 -CPT for 10 min on microbial growth and the quality attributes of the radish sprouts were evaluated during storage for 12 days at 4 and 10 °C. N 2 -CPT at 900 W and 667 Pa for 20 min reduced the number of S . typhimurium by 2.6 ± 0.4 log CFU/g. The moisture content of the radish sprouts decreased with treatment time. The appearance and odor of the radish sprouts were not altered by CPT ( p > 0.05) and this treatment did not affect the quality attributes of the sprouts in terms of color, ascorbic acid concentration, or antioxidant activity during storage at both 4 and 10 °C. These findings suggest that CPT has the potential to improve the microbiological safety of radish sprouts with reference to S . typhimurium during cold storage without significant detriment to its quality properties. [ABSTRACT FROM AUTHOR]

Sanitizing radish seeds intended for edible sprout production was achieved by applying simultaneous treatments with gaseous chlorine dioxide (ClO 2 ), high relative humidity (RH, 100%), and mild heat (55 °C). Gaseous ClO 2 was produced from aqueous ClO 2 (0.66 ml) by mixing sulfuric acid (5% w/v) with sodium chlorite (10 mg/mL) in a sealed container (1.8 L). Greater amounts of gaseous ClO 2 were measured at 23% RH (144 ppm after 6 h) than at 100% RH (66 ppm after 6 h); however, the lethal activity of gaseous ClO 2 against naturally occurring mesophilic aerobic bacteria (MAB) on radish seeds was significantly enhanced at 100% RH. For example, when exposed to gaseous ClO 2 at 23% RH, the number of MAB on radish seeds decreased from 3.7 log CFU/g to 2.6 log CFU/g after 6 h. However, when exposed to gaseous ClO 2 at 100% RH for 6 h, the MAB population decreased to 0.7 log CFU/g after 6 h. Gaseous ClO 2 was produced in higher amounts at 55 °C than at 25 °C, but decreased more rapidly over time at 55 °C than at 25 °C. The lethal activity of gaseous ClO 2 against MAB on radish seeds was greater at 55 °C than at 25 °C. When radish seeds were treated with gaseous ClO 2 (peak concentration: 195 ppm) at 100% RH and 55 °C, MAB were reduced to populations below the detectable level (<−0.7 log CFU/g) within 2 h without decreasing the seed germination rate (97.7%). The lethality of combined treatments against artificially inoculated Escherichia coli O157:H7 was also evaluated. When exposed to gaseous ClO 2 at 100% RH and 55 °C for 6 h, the initial number of E. coli O157:H7 (3.5 log CFU/g) on radish seeds decreased to below the detection limit (0.7 log CFU/g) by direct plating but it was not eliminated from seeds. The germination rate of radish seeds was not significantly ( P > 0.05) decreased after treatment for 6 h. The information reported here will be useful when developing decontamination strategies for producing microbiologically safe radish seed sprouts. [ABSTRACT FROM AUTHOR]