• Korean Journal of Environmental Agriculture
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• v.41 no.4
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• pp.344-354
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• 2022

BACKGROUND: Although antibiotics have contributed to treatment of bacterial infection, the antibiotic abuse can lead to antibiotic resistant bacteria. Impact of human activities on distribution of antibiotic resistance has been intensively issued and occurrence of antibiotic resistant bacteria in contaminated environments would not be a surprise. Nonetheless, anthropogenic contamination with the dissemination of antibiotic resistance along uncontaminated environments has been less considered. The aim of this study is to investigate antibiotic resistant bacteria across Ulleungdo, known as antibiotic resistance free and anthropogenic pollution free environment in Rep. of Korea. METHODS AND RESULTS: Antibiotic resistant bacteria in coastal seawater of Ulleungdo were investigated in July 2021. Antibiotic susceptibility test using the disk diffusion method was applied with six drugs according to the Clinical and Laboratory Standards Institute (CLSI) guideline. Total 43 bacterial isolates were tested and 20 isolates among of them showed multidrug resistance. Particularly, the number and ratio of resistant bacteria were relatively high in a densely populated area of Ulleungdo. The bacterial communities were investigated using 16S rRNA gene metabarcoding approach in the coastal seawater and soils of Ulleungdo. In the bacterial communities, Firmicutes were selectively distributed only in seawater, suggesting the possibility of anthropogenic contamination in coastal seawater of Ulleungdo. CONCLUSION(S): We found antibiotic resistant bacteria in a populated area of Ulleungdo. The occurrence of antibiotic resistant bacteria in Ulleungdo seems to result from the recent anthropogenic impact. Consistent monitoring of antibiotic resistant bacteria in the uncontaminated environment needs to considered for future risk assessment of antibiotics.

• Microbiology and Biotechnology Letters
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• v.51 no.2
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• pp.191-202
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• 2023

Elevated serum cholesterol is a main risk factor for heart disorders. Most probiotic products administered to lower cholesterol are dairy products which are not suitable for lactose-intolerant individuals. In this study, we assessed the cholesterol-lowering efficacy of LAB isolated from traditionally fermented drinks in diet-induced rats and determine their efficacy in the production of non-dairy, probiotic formulations using papaya juice. LAB were isolated from palm wine and corn beer on MRS agar using a pour-plate technique. Identification was carried out using 16S rRNA gene sequencing. A hypercholesterolemia model in which diet-induced Wistar albino rats were assigned into four groups was established. Oral gavage was carried out for 30 days. On the 31^st day, the rats were dissected and the serum lipid profile was analyzed using biochemical kits. A 10⁶ cfu/ml of a 24-h-old culture of selected lactobacilli was used to inoculate papaya juice and incubated at 37℃. Microbial and chemical changes were assessed during papaya fermentation and after four weeks of cold storage. Two selected isolates (Pw1 and Cb4) had in vitro cholesterol reduction of > 80%. These two isolates lowered lipid profile (triglyceride, total cholesterol, LDL-c) significantly, and increased HDL-c levels (p < 0.5) in the rat sera. Phylogenetic analysis showed that Pw1 was 98.86% similar to Limosilactobacillus fermentum, while Cb4 was 99.54% similar to Enteroccocus faecium. Both strains fermented papaya juice with cell viability reaching 8.92 × 10⁸ cfu/ml and 25.3 × 10⁸ cfu/ml respectively, and were still viable after 4 weeks of cold storage.

• Safety and Health at Work
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• v.1 no.2
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• pp.183-191
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• 2010

Objectives: The objective of this study is to investigate the distribution patterns and exposure concentrations of bioaerosols in industries suspected to have high levels of bioaerosol exposure. Methods: We selected 11 plants including 3 livestock feed plants (LF industry), 3 metal working fluids handling plants (MWFs industry), and 5 sawmills and measured total airborne bacteria, fungi, endotoxins, as well as dust. Airborne bacteria and fungi were measured with one stage impactor, six stage cascade impactor, and gelatin filters. Endotoxins were measured with polycarbonate filters. Results: The geometric means (GM) of the airborne concentrations of bacteria, fungi, and endotoxins were 1,864, $2,252\;CFU/m^3$, and $31.5\;EU/m^3$, respectively at the sawmills, followed by the LF industry (535, $585\;CFU/m^3$, and $22.0\;EU/m^3$) and MWFs industry (258, $331\;CFU/m^3$, and $8.7\;EU/m^3$). These concentrations by industry type were significantly statistically different (p < 0.01). The ratio of indoor to outdoor concentration was 6.2, 1.9, 3.2, and 3.2 for bacteria, fungi, endotoxins, and dust in the LF industry, 5.0, 0.9, 2.3, and 12.5 in the MWFs industry, and 3.7, 4.1, 3.3, and 9.7 in sawmills. The respiratory fractions of bioaerosols were differentiated by bioaerosol types and industry types: the respiratory fraction of bacteria in the LF industry, MWF industry, and sawmills was 59.4%, 72.0%, and 57.7%, respectively, and that of fungi was 77.3%, 89.5%, and 83.7% in the same order. Conclusion: We found that bioaerosol concentration was the highest in sawmills, followed by LF industry facilities and MWFs industry facilities. The indoor/outdoor ratio of microorganisms was larger than 1 and respiratory fraction of microorganisms was more than 50% of the total microorganism concentrations which might penetrate respiratory tract easily. All these findings suggest that bioaerosol in the surveyed industries should be controlled to prevent worker respiratory diseases.

• Journal of Food Hygiene and Safety
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• v.19 no.1
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• pp.49-54
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• 2004

The prevention of infectious disease from contaminated foods is very important in public health. Quantitative microbial risk assessment has been used in advance countries to achieve the safety of public health against hazardous microbial causing contaminated foods. This study was conducted to estimate maximum edible time without producing enterotoxin from Staphylococcus aureus in Kimbap selling at different domestic store using Food MicroModel and monitoring data and to compute maximum edible time by temperature with 99th percentile safety probability based on only restaurant data. For estimating maximum edible time, model operation conditions like reaching time at 2 ${\times}$ 10$^{7}$ , which enterotoxin was known as producing point from S. aureus, temperature of 28∼3$0^{\circ}C$, pH 5.2, NaCl 0.22%, aw(water activity) 0.99, and intaking one serving size of 171g in Kimbap were considered. Estimated maximum edible times by regarding outdoor temperature in summer were 3.9∼4.6 hrs in restaurant, 6.7∼7.9 hrs in department store and 7.4∼8.7 hrs in convenient store. Based on restaurant data, estimated maximum edible times with 99th percentile safety probability by temperature were 1.9 hrs in 3$0^{\circ}C$ and 17.7 hrs in 15$^{\circ}C$.

• Journal of Food Hygiene and Safety
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• v.36 no.4
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• pp.324-330
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• 2021

In this study, the microbial levels on mixed vegetable salads, fresh fruits, and frozen fruits distributed in Korea were comparatively analyzed by food group, region, and quarter. Samples were collected from big markets in large cities from 2018 to 2019 and used for microbiological analysis. The levels of aerobic bacteria for mixed vegetable salads, fresh fruits, and frozen fruits were 6.48, 5.07, and 3.78 log CFU/g, respectively. As a result of analyzing the quarterly contamination levels of aerobic bacteria, the first quarter contamination level was 5.12 log CFU/g while the second quarter showed 6.26 log CFU/g, the third quarter 5.73 log CFU/g, and the fourth quarter 4.42 log CFU/g. A higher number of aerobic bacteria was observed in the second and third quarters when the temperature was higher. There was no difference in the number of bacteria by region. The levels of the coliform group were 1.98 - 3.93 log CFU/g in all samples, and Escherichia coli was detected at 1.38 log CFU/g in 3 out of 27 mixed vegetable salads. Since the mixed vegetable salad and fresh fruit used in this study exceeded the standard (3 log CFU/g) for unheated foods and E. coli was detected in three fresh fruits, stricter hygiene management in the manufacturing stage of salads and fresh fruit is required.

• Korean Journal of Food Science and Technology
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• v.41 no.4
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• pp.392-398
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• 2009

This study identified risk factors of cross-contamination of foodborne pathogens and established a good agricultural practice (GAP) system for an agricultural products processing center (APC) for perilla leaves. All samples were collected before and after a standard work shift at the APC, while perilla leaves were also collected after each step in the APC. In addition, the workers and their surroundings were sampled by swabbing. The total plate count (TPC) and coliform count in the water samples increased significantly (p<0.05) to 3.36 and 1.73 log CFU/mL after work, respectively. However, no Escherichia coli and Listeria monocytogenes were detected. The bacterial populations of the workers and their surroundings did not differ significantly (p${\geq}$0.05) before and after work. However, Staphylococcus aureus (<1.66 log CFU) was detected at a high rate (13-50%) in the basket, packing table, gloves and cloth. Although perilla leaves passed through the washing steps, the TPC and coliform bacterial populations on the final products were higher (p${\geq}$0.05) than those of unwashed perilla leaves, which indicates that the washing system was not functioning properly. Accordingly, a GAP system with a better washing system should be employed at this facility.

• Korean journal of food and cookery science
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• v.30 no.3
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• pp.249-261
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• 2014

This study was performed in order to grasp the trends of elementary school children and their parents on their purchasing behavior of processed foods, awareness of food additives and its education experience by analyzing the safety assessment reports of food additives in 2008~2013. The most important factor in purchasing processed foods was safety in both groups followed by nutrition in parents and taste in children, respectively. While purchasing foods, the first item that is checked has been shifted from food additives to the origin of the products. Parents still perceived food additives as the most hazardous factor for food safety; however, recently, children began to regard microbial contaminants as being most hazardous, which is regarded as a desirable educational effect. The most concerned food additives were preservatives, synthetic seasoning and colorants in both groups. However, the awareness level on food additives still remained low as 3.0~3.1/5.0 for parents and 2.4~2.9/5.0 for children. Educational experience on food additives increased in children from 12% in 2008 to 25% in 2013; however, it decreased in parents from 23% in 2008 to 15% in 2013. Information needs for food additives by education and promotion were very high both in parents (4.2~4.5) and children (3.8~4.1). Both groups had an interest in the safety, legal standards of food additives, and foods with food additives, in order. The most reliable resource institutions on food additives were university/research institute and hospital for parents, but, hospital and government for children. The preferred media on food additives were TV and the internet for parents, and school newsletter and TV for children. Overall, the above results demonstrated that the perceptions on food additives did not change much with parents during the last 6 years; however, children's perceptions began to show improvement with the increase of educational experience. Hence, the government needs to make efforts to increase the trust level of consumers by developing educational tools and providing educational experiences including mass media for the promotion of risk communication on food additives.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.122-128
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• 2005

Contamination levels of total aerobic bacteria, coliforms, Esherichia coli, Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes of Kimbab and its main ingredients sampled from general and specialized restaurants were compared. Total aerobic bacteria and coliform counts of Kimbab samples from both restaurant types were not significantly different (p>0.05), showing approximately $4\;to\;6\;log_{10}CFU/g$. E. coli counts were significantly higher in kimbab from general restaurants ($65%:\;0.7-2.6\;log_{10}CFU/g$) than those from specialized ones ($8.33%:\;0.70log_{10}CFU/g$), whereas those of S. aureus and B. cereus were not significantly different (p>0.05). L. monocytogenes was not detected in all Kimbab samples. These results indicate hygiene of Kimbab and its main ingredients are deleterious. Contamination levels of pathogens determined in the present study may be used as primary data for microbial risk assessment.

• Journal of Food Hygiene and Safety
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• v.20 no.1
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• pp.43-47
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• 2005

This study monitored and compared the contamination levels of total aerobic bacteria, coliforms, Escherichia coli, and L. monocytogenes of either lettuce, sesame leaf, or cucumber sampled from either 15 super markets(SM) or 21 traditional markets(TM) located in both Seoul and the southern part of Gyunggi. Contamination levels of total aerobic bacteria and coliforms in lettuce, sesame leaf, or cucumber from SM or TM were not (p>0.05) significantly different. The highest contamination levels of total aerobic bacteria were observed in lettuce and followed by sesame leaf and cucumber. The contamination levels of total aerobic bacteria in lettuce, sesame leafs, and cucumbers were $7.01{\pm}0.14\;log_{10}CFU/g(SM)$ and $7.10{\pm}0.11\;log_{10}CFU/g(TM)$, $6.69{\pm}0.20\;log_{10}CFU/g(SM)$ and $6.44{\pm}0.13\;log_{10}CFU/g(TM)$, and $5.37{\pm}0.25 \;log_{10}CFU/g(SM)$ and $5.27{\pm}0.19\;log_{10}CFU/g(TM)$, respectively. A similar pattern of contamination rank was observed with the coliforms in three vegetables as was observed with the total aerobic bacteria E. coli were not significantly (p>0.05) different between SM and TM and isolated over $30\%$ in lettuce and sesame leaf and below $10\%$ in cucumbers. L. monocytogenes were not detected in all three vegetables(ND: cucumber <3 CFU/g, lettuce and sesame leaf <10 CFU/g). The microbial contamination levels determined in the present study may be used as the primary data to execute microbial risk assessment of fresh vegetables.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.207-218
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• 2008

The impacts of planted transgenic rice varieties on bacterial communities in paddy soils were monitored using both cultivation and molecular methods. The rice field plot consisted of eighteen subplots planted with two genetically modified (GM) rice and four non-GM rice plants in three replicates. Analysis with denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes revealed that the bacterial community structures were quite similar to each other in a given month, suggesting that there were no significant differences in bacterial communities between GM and non-GM rice soils. The bacterial community structures appeared to be generally stable with the seasons, as shown by a slight variation of microbial population levels and DGGE banding patterns over the year. Comparison analysis of 16S rDNA clone libraries constructed from soil bacterial DNA showed that there were no significant differences between GM and non-GM soil libraries but revealed seasonal differences of phyla distribution between August and December. The composition profile of phospholipid fatty acids (PLFA) between GM and non-GM soils also was not significantly different to each other. When soil DNAs were analyzed with PCR by using primers for the bar gene, which was introduced into GM rice, positive DNA bands were found in October and December soils. However, no bar gene sequence was detected in PCR analysis with DNAs extracted from both cultured and uncultured soil bacterial fractions. The result of this study suggested that, in spite of seasonal variations of bacterial communities and persistence of the bar gene, the bacterial communities of the experimental rice field were not significantly affected by cultivation of GM rice varieties.