• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.264-270
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• 2012

This study was performed to compared the effectiveness of individual treatments (electrolyzed water: EW, organic acid, and ultrasound) and their combination on reducing foodborne pathogens from perilla leaves. Perilla leaves were innoculated with a cocktail of Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus. Inoculated perilla leaves were treated with EW combined with different concentration of acetic acid (0.5%, 1.0%, 1.5%, 2.0%) for 1 min at room temperature. Treatment of 3 pathogens on perilla leaves with electrolyzed water combined with ultrasound (25 kHz) and 0.5% acetic acid was also performed for 1 min. While the numbers of S. Typhimurium and B. cereus showed reduced with increasing acetic acid concentration, there is no difference in the number of S. aureus treated with EW containing 0.5% to 1.5% acetic acid. Discoloration was observed the perilla leaves treated with EW combined with more than 1.0% acetic acid. For all three pathogens, the combined treatment of EW and ultrasound resulted in additional 0.42 to 0.72 $log_{10}$ CFU/g. The maxium reductions of S. Typhimurium and B. cereus were 0.95, 1.23 $log_{10}$ CFU/g after treatment with EW combined with 0.5% acetic acid and ultrasound simultaneously. The results suggest that the treatment of EW combined with 0.5% acetic acid and ultrasound increased pathogens reduction compared to individual treatment.

• Journal of Microbiology and Biotechnology
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• v.26 no.1
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• pp.197-206
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• 2016

Listeria monocytogenes is a foodborne pathogen of considerable genetic diversity with varying pathogenicity. Initially, we found that the strain M7 was far less pathogenic than the strain Lm850658 though both are serovar 4a strains belonging to the lineage III. Comparative genomic approaches were then attempted to decipher the genetic basis that might govern the strain-dependent pathotypes. There are 2,761 coding sequences of 100% nucleotide identity between the two strains, accounting for 95.7% of the total genes in Lm850658 and 92.7% in M7. Lm850658 contains 33 specific genes, including a novel 20K prophage whereas strain M7 has 130 specific genes, including two large prophages (38K and 44K). To examine the roles of these specific prophages in pathogenicity, the 20K and 38K prophages were deleted from their respective strains. There were virtually no differences of pathogenicity between the deletion mutants and their parent strains, although some putative virulent factors like VirB4 are present in the 20K region or holin-lysin in the 38K region. In silico PCR analysis of 29 listeria genomes show that only strain SLCC2540 has the same 18 bp integration hotspot as Lm850658, whereas the sequence identity of their 20K prophages is very low (21.3%). The 38K and 44K prophages are located in two other different hotspots and are conserved in low virulent strains M7, HCC23, and L99. In conclusion, the 20K and 38K prophages of L. monocytogenes serovar 4a strains Lm850658 and M7 are not related to virulence but contribute to genetic diversity.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.437-442
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• 2014

Foodborne illness due to the consumption of contaminated raw strawberries is a continuing food safety concern. This study investigated and evaluated contamination levels of bacteria on strawberries at farms stage to evaluate potential hazards associated with fresh strawberries. A total of 315 samples, 105 samples from 5 sampling sites (A to E) of 21 farms and 210 samples from 1 sampling site of 6 farms, was collected every month for four months and analyzed to enumerate aerobic bacterial counts, Coliforms/E. coli, Bacillus cereus and Staphylococcus aureus. In addition, the prevalence study of five pathogens (S. aureus, E. coli, E. coli O157:H7, Salmonella spp. and Listeria monocytogenes) was performed on each sample. Aerobic bacterial counts ranged from 0.48 to 6.36 Log CFU/g, with the highest bacterial cell counts recorded for D and E sites. Coliforms were detected in 71 samples (22.5%) with a minimum of 0.48 cfu/g and a maximum of more than 4 Log CFU/g. B. cereus was detected in 98 samples (31.1%) among total samples analyzed. S. aureus was detected in 2 samples with a minimum of 0.48 Log CFU/g and a maximum of 1.38 Log CFU/g. E. coli, E. coli O157:H7, Salmonella spp. and L. monocytogenes were not isolated from any of the samples. The microbial contamination levels of strawberries determined in this study may be used as the fundamental data for microbiological risk assessment.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1152-1161
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• 2007

An immunochromatography (ICG) strip test based on a monoclonal antibody for the rapid detection of L. monocytogenes in meat and processed-meat samples was developed in this study. A monoclonal antibody (MAb) specific to L. monocytogenes was produced from cloned hybridoma cells (FKLM-3B12-37) and used to develop an ICG strip test. The antibody showed a stronger binding to L. monocytogenes than other Listeria species, and a weak cross-reaction to S. aureus based on an ELISA. The detection limit of the ICG strip test was $10^5\;cell/ml$. In total, 116 meat and processed-meat samples were collected and analyzed using both the ICG strip test and a PCR. The ICG strip test and PCR indicated L. monocytogenes contamination in 34 and 27 meat samples, respectively. The 7 meat samples not identified as L. monocytogenes positive by the PCR were also tested using an API kit and found to be contaminated by Listeria species. In conclusion, the ICG strip test results agreed well with those obtained using the PCR and API kit. Thus, the developed ICG has potential use as a primary screening tool for L. monocytogenes in various foods and agricultural products, generating results within 20 min without complicated steps.

• Korean Journal of Veterinary Service
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• v.43 no.1
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• pp.23-29
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• 2020

Hepatitis E Virus (HEV) infection is a worldwide disease and the primary cause of acute viral hepatitis in the world. It can be isolated from many different species including pigs. HEV is a zoonotic pathogen and foodborne disease. The main animal reservoir is domestic pigs. It is usually asymptomatic in pig but it is a public health concern, causing acute hepatitis in humans of varying severity. This study focused on the presence of HEV in pig and pork product. One hundred feces and one hundred fifty serum samples were randomly collected from pigs in slaughterhouses in Gwangju from November in 2018 to February in 2020. In addtion, seventy-five pork products were collected from markets in Gwangju. Feces and pork product samples were examined for the presence of HEV RNA using an reverse-transcription realtime PCR (RT-qPCR) assay. Serum samples were tested for the presence of HEV-specific IgG antibodies using Enzyme-linked immunosorbent assay (ELISA). HEV antigen and antibody positive rates were 3.0% (3/100) and 19.3% (29/150), respectively, in Gwangju and nearby areas such as Jeonnam and Jeonbuk. However, HEV antigen was not detected from any of pork product in this study. In conclusion, the prevalence of HEV should be continuously monitored because HEV was sporadically detected in Gwangju and nearby areas.

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.330-335
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• 2011

This study was performed to determine the transfer rates of each foodborne pathogen from pork meat packaging during the processing. We analyzed the transfer rate of Listeria monocytogenes from contaminated pork meat to worker's hands (wearing polyethylene gloves, PEG; cotton gloves, CG; and bare hands), cutting boards and knives, and vice versa. Transfer rate of CG 100.00% was higher than that of bare hands 2.513% and PEG 1.511%. In particular, when wearing Co, the transfer rate from the CG to bare hands with CG was 0.08%. Also, the range of transfer rates from contaminated pork meat to cutting board and knife was 0.352-3.791%. In contrast, transfer rates from the workers' hands (with PEG/CG and bare hands) to cutting board, knife, and pork meat ranged from 0.001 to 0.141%. There was a lower transfer rate from workers' hands than from pork meat. These findings indicate that use of PEG could effectively reduce or prevent the cross-contamination compared to CG and provide important information concerning the consecutive transfer of L. monocytogenes during food processing.

• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.154-159
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• 2011

Inadequate food handling and poor hand hygiene playa major role in the occurrence of foodborne diseases. The objective of this study was to find out if the level of microbial contamination on the hands of food preparers varies by time during their working period. This study focused on the contamination of aerobic plate count, total and fecal coliforms, Escherichia coli, Staphylococcus aureus, and Salmonella spp. Sampling from left hand and right hand of twenty food preparers was done with glove-juice method at every two hours during their work. Microbiological testing was conducted according to the Food Code of Korea. The microbiological load on the hands was changed over time. Samples taken from their hands before work and at 8 hours showed higher levels of bacteria than those taken at 2, 4, and 6 hours during work and/or after work (p < 0.05). The contamination levels of microorganisms were consistently higher in right hand than in left hand. Poor hand hygiene practices were indicated by the positive results for total and fecal coli forms, E. coli, S. aureus, and Salmonella spp. on the hands of some food preparers. This study indicates food preparers' hands can be a vehicle of pathogen during their work. The results of this study emphasize the importance of hand hygiene education and training targeting the food preparers.

• Food Science of Animal Resources
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• v.30 no.5
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• pp.819-825
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• 2010

This study was conducted to investigate the effect of various natural ingredients for manufacturing meat products on the $D_{10}$ value and relative radiation sensitivity (RRS) of foodborne pathogens inoculated into ground beef. The pathogens used for this study were Salmonella Typhimurium (KCTC 1925), Escherichia coli (KCTC 41682), Listeria monocytoges (KCTC 3569), and Staphylococcus aureus (KCTC 11764), and the natural ingredients added into ground beef were garlic, onion, black pepper, hot pepper, ginger, green onion, carrot, and red wine. The $D_{10}$ of E. coli was decreased significantly by 5% of garlic addition (RRS=1.460), and the addition of carrot (RRS=1.086) and red wine (RRS=2.864) also showed similar results. Most natural ingredients were effective in increasing radiation sensitivity of L. monocytogens, but only garlic, onion, hot pepper, carrot, and red wine were effective against S. aureus. In particular, the addition of red wine to ground beef showed the greatest increase of radiation sensitivity for 3 pathogens tested in the present study, except for S. Typhimurium. Results indicate that the use of certain natural ingredients for manufacturing processed meat products may have effects in the increase of radiation sensitivity of pathogens. This increased radiation sensitivity can reduce the target irradiation dose for obtaining the same level of safety, resulting in lowering the adverse quality changes caused by a high-dose irradiation process.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.24-29
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• 2012

A total of 187 samples of leafy vegetables and fruits were acquired at traditional markets and department stores in Seoul, Korea. Samples were tested for microorganism distributions and for the presence of pathogenic bacteria. The aerobic mesophilic counts ranged between 2.5 and 9.4 log CFU/g, with the highest count recorded from the dropwort. Counts of psychrotrophic microorganisms were as high as those of the mesophilic microorganisms. Total coliform populations between 1.0 and 7.8 log CFU/g were found in 90.9% of the samples. Microbiological counts for fruits were very low. $Escherichia$ $coli$ was isolated in 24 (12.8%) samples. $Staphylococcus$ $aureus$ and $Clostridium$ $perfringens$ contamination were found in 15 (8.0%) and 20 (10.7%) samples. $Salmonella$ species and $Listeria$ $monocytogenes$ were detected in 2.7 and 0.5% of samples, respectively. Among the total 187 samples, 8 samples were contaminated by more than two pathogens. $E.$ $coli$ O157:H7 was not detected in any of the samples. The microbial contamination levels determined in the present study may be used as the primary data to execute microbial risk assessment of fresh vegetables and fruits.

• Journal of Food Hygiene and Safety
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• v.28 no.4
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• pp.312-318
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• 2013

This study validated microbiological hazards of ginseng farms at the cultivation stage and suggested recommendations to develop a good agricultural practices (GAP) model. A total of 96 samples were collected from cultivation environments (soil, irrigation water, and atmosphere), plants (ginseng and its leaf), personnel hygiene (glove, cloth, and hand) of 3 ginseng farms (A, B, and C) and were tested to analyze sanitary indicator bacteria (aerobic plate count, coliforms and Escherichia coli), major foodborne pathogens (E. coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, and Bacillus cereus), and fungi. Total bacteria, coliform, and fungi in the 3 ginseng farms were detected at the level of 1.3~6.0, 0.1~5.0, and 0.4~4.9 v/g (or mL, hand, and $100cm^2$), respectively. Only irrigation water collected from one ginseng farm was confirmed to be E. coli positive. In case of pathogenic bacteria, B. cereus was detected at levels of 0.1~5.0 log CFU/g (or mL, hand, and $100cm^2$) in all samples, but other pathogen bacterias were not detected in any samples from all farms. Although E. coli were detected in irrigation water, the level of microbial for the three farms was lower than the regulation limit. According to the results, the ginsengs produced from the 3 farms were comparatively safe with respect to microbiological hazard. However, cross-contamination of bacteria from environments and workers to ginseng has been considered as potential risks. Therefore, to minimize microbial contamination in ginseng, GAP model should be applied for ensuring the safety of ginsengs.