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The diverse microbial communities in kimchi are dependent on fermentation period and temperature. Here, we investigated the effect of enterotoxigenic Escherichia coli (ETEC) during the fermentation of kimchi at two temperatures using high-throughput sequencing. There were no differences in pH between the control group, samples not inoculated with ETEC, and the ETEC group, samples inoculated with ETEC MFDS 1009477. The pH of the two groups, which were fermented at 10 and 25°C, decreased rapidly at the beginning of fermentation and then reached pH 3.96 and pH 3.62. In both groups, the genera Lactobacillus, Leuconostoc, and Weissella were predominant. Our result suggests that microbial communities during kimchi fermentation may be affected by the fermentation parameters, such as temperature and period, and not enterotoxigenic E. coli (ETEC).

These days, bacterial detection methods have some limitations in sensitivity, specificity, and multiple detection. To overcome these, novel detection and identification method is necessary to be developed. Recently, NGS panel method has been suggested to screen, detect, and even identify specific foodborne pathogens in one reaction. In this study, new NGS panel primer sets were developed to target 13 specific virulence factor genes from five types of pathogenic Escherichia coli, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium, respectively. Evaluation of the primer sets using singleplex PCR, crosscheck PCR and multiplex PCR revealed high specificity and selectivity without interference of primers or genomic DNAs. Subsequent NGS panel analysis with six artificially contaminated food samples using those primer sets showed that all target genes were multi-detected in one reaction at 10

Background: The present study examined the changes in microbiological composition during the production process of crab marinated in soy sauce, potential microbial hazards, potential contamination routes and effective critical control points. Crab and soy sauce samples were obtained from six different manufacturing plants at different stages, and their microbiological content was comprehensively assessed by quantitative and qualitative analyses.; Results: The results revealed the following: (1) the final products contained 4.0 log colony-forming units (CFU) g-1 aerobic plate counts (APCs) and 1.1 log CFU g-1 coliforms, which may have been introduced from the raw materials (the level of APCs in raw crab and soy sauce mixed with other ingredients was 3.8 log CFU g-1 and 4.0 log CFU mL-1 respectively); (2) marination of crab in soy sauce may allow cross-contamination by coliforms; (3) only Bacillus cereus and Staphylococcus aureus were qualitatively detected in samples at different stages of manufacture (detection rate of 28 and 5.6% respectively), and these bacteria may impact the microbiological quality and safety of crab marinated in soy sauce; and (4) bacterial counts were either maintained or increased during the manufacturing process (suggesting that no particular step can be targeted to reduce bacterial counts).; Conclusion: Proper management of raw materials and the marination process are effective critical control points, and alternative interventions may be needed to control bacterial quantity. The results provide important basic information about the production of crab marinated in soy sauce and may facilitate effective implementation of sanitary management practices in related industries and research fields. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

This study examined the prevalence of seven species of Enterococcus in foodstuffs (n = 500) retailed in South Korea and identified the potential virulence of isolates. The overall detection rate of Enterococcus spp. was 68.2%, and the bacteria were most prevalent in refrigerated chicken (84.1%), followed by refrigerated pork (71.0%), frozen chicken (60.0%), leafy vegetables (56.0%), and refrigerated beef (53.0%). The prevalence differed by sample type: E. faecalis and E. faecium were the most or second most frequently identified species in foods of animal origin, while a large portion of the leafy vegetable isolates were confirmed as E. casseliflavus. The presence of virulence genes was apparent in all species except E. durans; approximately half of the isolates (46.3%) had more than one virulence determinant, especially gelE (gelatinase) (88.1%). One of the interesting findings was that even non-E. faecalis and non-E. faecium enterococci also had virulence determinants. However, none of the Enterococcus isolates were resistant to vancomycin. These results provide comprehensive data on the prevalence of the genus Enterococcus in South Korea and empirical evidence regarding the virulence potential; thus, the findings herein call for further studies about the relevance of these bacteria to food safety.

The national incidence of foodborne illness reported by public health surveillance systems is lower than the actual incidence due to underdiagnosis and underreporting. Therefore, it is necessary to estimate the actual cases of foodborne illness at a national level. This study used a simple method of polling and estimation that overcomes the problem of lack of data. A national survey of the experience, diagnosis with and/or treatment for, and/or hospitalization for foodborne illness among a representative sample in South Korea was conducted. The survey results were then used to estimate the actual incidence of foodborne disease using a simulation method that expressed the estimated values as 95% confidence intervals (CI) to address uncertainty. Among the 1439 respondents for whom valid data were collected, 19.18% had experienced, 3.13% had been diagnosed with and/or treated for, and 0.28% had been hospitalized for foodborne disease. Using these results, it was estimated that 9.59 (95% CI: 8.57–10.61) million individuals experience, 1.56 (95% CI: 1.11–2.01) million are diagnosed with and/or treated for, and 140,000 (95% CI: 30,000–280,000) are hospitalized for foodborne diseases annually in South Korea. The estimated number of patients hospitalized for foodborne disease is approximately 20 times higher than that of the number of reported cases in Ministry of Korean Food and Drug Safety, indicating that a large number of cases are unreported. Consideration of these results will be useful for the prevention and control of foodborne disease in South Korea and allow for international comparison of the incidence of foodborne illness.

The objectives of the current study were to investigate the fate of microbial indicators [aerobic plate counts (APC), total coliforms (TC), and lactic acid bacteria (LAB)] in commercial salted napa cabbages during storage conditions at different temperatures (5, 22, and 30 °C, for up to 72 h) and to develop a predictive growth model using the modified Gompertz equation to determine shelf life. Microbial population sizes (initial log CFU g −1 : APC, 5.1; TC, 3.0; LAB, 3.7) remained stable at 5 °C, but rapidly increased by 2–4 log CFU g −1 within 12 h at 22 and 30 °C; furthermore, the pH of salted napa cabbages decreased significantly ( P 2 ≧ 0.97), the highest μ max was observed for LAB at 30 °C [0.61 log CFU h −1 ], while the lowest was noted for TC at 5 °C [0.04 log CFU h −1 ]. Shelf-life was determined using APC (7.7 log CFU g −1 ) and LAB (6.0 log CFU g −1 ) limits; the microbiological acceptability period of salted napa cabbage was predicted to be 12.6 and 9.3 h at 22 and 30 °C, respectively. Thus, consumers should use the product within 12 h of storage at room temperature (more quickly in the summer (9 h)), or store it in a refrigerator. The presented research proposes a shelf-life modeling of commercial salted napa cabbages, which may be used as a scientific basis for product quality control and issuing appropriate guidance for consumer use at home.

The effects of freezing (−20 °C and −40 °C for 6 h, 12 h, and 1–21 days), salting (5, 10, 15, and 20% NaCl for 3 h, 6 h, 12 h, and 1–7 days), and a combined treatment with chlorine (500, 1000, 1500, and 2000 ppm) and ultrasound (37 kHz frequency and 1200 W for 5, 10, 15, 20, and 30 min) were investigated to observe the inactivation of Anisakis larvae in salt-fermented squid and pollock tripe or in the test tube. All larvae inoculated in squid and pollock tripe were inactivated after 48 h at −20 °C and 24 h at −40 °C. The average recovery rates of the larvae inoculated in squid and pollock tripe were 94.4% and 95.2%, respectively. The viabilities of larvae were 81.7% in 5% NaCl and 26.7% in 10% NaCl after 7 days of storage. However, all larvae were inactivated when submerged in 15% NaCl after 7 days of storage and 20% NaCl after 6 days of storage. Viability was reduced from 43.3% to 13.3% when ultrasound alone was used to treat live larvae in test tubes for 15–20 min. Furthermore, although no reduction effect on viability of larvae was observed when chlorine alone was used for treatment, 0% viability was observed using the combined treatment of 1500 ppm chlorine and ultrasound for 30 min. Interestingly, when the viscera of heavily parasitized conger eels were treated with chlorine and ultrasound, there was no reduction effect on viability of the larvae on the viscera. These results could be used to provide more specific guidelines for manufacturers and consumers about the freezing and salting conditions necessary to kill Anisakis larvae in salt-fermented squid and pollock tripe.

Pathogenic Escherichia coli (PEc) is a leading cause of both foodborne and waterborne illness. In September 2012, a major foodborne outbreak with PEc occurred, affecting approximately 1,200 students and food handlers from 7 schools in Gyeonggi province, South Korea caused by contaminated kimchi. For detection of PEc in kimchi, real-time polymerase chain reaction (RT-PCR) and traditional culture methods were used. EAEC and ETEC genotypes were identified in samples from individuals with the illness and in kimchi using conventional PCR. Bacteria in stool samples were genetically similar to bacteria from kimchi (98% homology). PEc from kimchi was identified as the causative agent of a foodborne outbreak in South Korea. A significant link between kimchi and individuals with foodborne illnesses after consuming kimchi was demonstrated.

We employed Caenorhabditis elegans as a model to study the effectiveness of sanitizers in killing pathogenic Escherichia coli strains ingested by free-living nematodes. Adult worms that had fed on six pathogenic E. coli strains (highly persistent in the nematode intestine) were treated with three chemical solutions. In planktonic cells, none of the H2O2 and acetic acid treatments influenced the survival of the pathogenic E. coli strains, whereas sodium hypochlorite critically decreased the viability of the strains. Importantly, the survival of the E. coli strains was dramatically increased by persistence in the C. elegans gut under 0.1% sodium hypochlorite, and several strains could survive at a concentration of 0.5%. In addition, all pathogenic E. coli strains in the C. elegans gut survived on the lettuce for 5 days even though they were washed with 0.1% sodium hypochlorite. Taken together, our results indicate that pathogenic E. coli ingested by C. elegans may be protected against washing treatment with commercial sanitizers on raw food materials.

The Nocardia sp. L-417 strain grown with n-hexadecane as a carbon source produced two types of biosurfactant that have different characteristics. These biosurfactants were purified by procedures that included ammonium sulphate fractionation, chilled acetone and hexane treatments, silica-gel column chromatography and Sephadex LH-20 gel filtration. The purified biosurfactants were very stable over a broad range of pHs (2-12) and temperatures (100 degrees C, 3 h). The biosurfactant type I had strong properties as an emulsifying agent and as an emulsion-stabilizing agent, whereas type II had a strong ability to reduce surface tension.