• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.503-509
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• 2012

Objectives: This study was performed in order to evaluate the generation characteristics of airborne bacteria and fungi while operating a household humidifier, in consideration of user habits. Methods: Microbial samples were collected in a closed chamber with a total volume of 2.76 $m^3$, in which a humidifier was operated according to experimental strategies. A cultivation method based on the viable counts of mesophilic heterotrophic bacteria and fungi was performed. Experimental strategies were divided into three classes: the type of water in the water reservoir (tap water, cooled boiled water); the frequency of filling the reservoir (refill every day, no refill); and the sterilization method (sterilization function mode, humidifier disinfectants). Results: Significant increases in the concentration of airborne bacteria were observed while the humidifier was in operation. The concentration had increased to 2,407 $CFU/m^3$ by 120 hours when tap water filled the reservoir without any application of sterilization, while for cooled boiled water, it was merely 393 $CFU/m^3$ at a similar time point. Usages of disinfectant in the water tank were more effective in decreasing bioaerosol generation compared to sterilization function mode operation. Generation characteristics of airborne fungi were similar to those of bacteria, but the levels were not significant in all experiments. Calculated exposure factor can be used as an indicator to compare biorisk exposure. Conclusion: This study identified the potential for bioaerosol generation in indoor environments while operating a household humidifier. User practices were critical in the generation of bioaerosol, or more specifically, airborne bacteria. Proper usage of a humidifier ensures that any biorisks resulting from generated bioaerosol can be prevented.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.365-371
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• 1995

Filamentous bacteria and other large microorganisms, which are useful indicators of bulking and poeration, were identified by microscopic observation. Activated sludge samples were taken from the aeration basin of 5 municipal wasterwater plants and 6 industrial ones. Among the filamentous bacteria founds, Microthrix parvicella was most frequently present, followed by type 0041, type 1701 and Nocardia. This frequency of occurrence was similar to those reorted in USA and the Neterland. The morphology of filamentous bacteria observed were generally identical with those previously reported. except type 1701 which had slender filament diameter. Among protozoa, Vorticella was most frequently present, followed by Aspidisca, Opercularia and Difflugia. Philodina was the only metazoa observed. Both filamentous bacteria and protozoa would be useful indicator organisms. The potential for these organisms as indicators were discussed.

• Food Science and Industry
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• v.50 no.3
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• pp.51-59
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• 2017

Due to the nature of HMR food that is susceptible to contamination, its safety management is becoming more important. The relevant food types in food code corresponding to HMR foods are addressed, and the criteria for hygiene indicator bacteria and food poisoning bacteria, and storage and distribution standards according to the product type were presented. The government's safety management for HMR foods is basically carried out through the Food Sanitation Act. Those who intend to do HMR business must complete business registration or declaration, hygiene education, health examination of employees, and comply with legal obligations such as HACCP application. The government confirms compliance with legal requirements through hygiene inspection and monitoring inspection of products. However, the safety of HMR foods is not realized by the safety management system alone. A food safety culture should be established in which industry workers and consumers carry out actions to ensure food safety.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.31-37
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• 2018

This study was conducted to evaluate the microbiological safety of leafy vegetables (perilla leaf and lettuce) in relation to cultivation methods. A total of 2,304 samples were collected from plants, harvesting tools and soil mulching film during the production and harvest stages from organic- and conventional- farms. From the samples, sanitary indicator microorganisms (total aerobic bacteria, coliforms, E. coli., Environmental Listeria, and yeast and mold) and pathogenic microorganisms (S. aureus, B. cereus, Salmonella spp., Clostridium spp., and L. monocytogenes) were analyzed. In the production stage of leafy vegetables, the sanitary indicator microorganisms was not detected regardless of cultivation method or it was detected to be less than $3.4\;Log\;CFU/100cm^2$. B. cereus and S. aureus were found to be 0.22~1.55 Log CFU/g in perilla leaf and lettuce produced by organic farms, and S. aureus was not detected and B. cereus was found to be 0.42~2.19 Log CFU/g in conventional farms. There were no significant differences between two cultivation methods. In the harvesting tools and soil mulching film, the contamination levels of sanitary indicator microorganisms and pathogenic microorganisms was low regardless of the cultivation method. However, there was a positive correlation ($R^2=0.4526$) in that the higher the microbial contamination level in the harvesting tool, the higher the microbial contamination on the surface of the plant. In addition, sanitary indicator microorganisms and pathogenic microorganisms were not detected or low in soil mulching during the production of organic leafy vegetables. As a result of this study, microbial hygiene control by soil mulching and harvesting tools was more important than difference of cultivation method in production of leafy vegetables.

• Food Science and Preservation
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• v.15 no.4
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• pp.491-496
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• 2008

To develop a freshness indicator of Chonggak-kimchi for marketing purposes, Chonggak-kimchi was prepared and pH, total acidity, total aerobic bacterial load, lactic acid bacterial levels, and reducing sugar content were measured. Sensory evaluation tests on product stored at $4^{\circ}C,\;10^{\circ}C,\;and\;20^{\circ}C$, were performed. The pH increased slightly early in storage, and then decreased to pH 4.2-4.3 for all samples. The rate of decrease of pH rose with increasing storage temperature. Total acidity values rapidly increased after 1, 5, and 7 days of storage at $20^{\circ}C,\;10^{\circ}C,\;and\;4^{\circ}C$, respectively. Populations of total aerobic bacteria and lactic acid bacteria increased slightly until 4 days, 10 days, and 30 days of storage at $20^{\circ}C,\;10^{\circ}C,\;and\;4^{\circ}C$, respectively, and then decreased drastically. Sensory evaluation data showed that Chonggak-kimchi was edible until 4 days(pH 4.5), 10 days(pH 4.4), and 30 days(pH 4.3) of storage at $20^{\circ}C,\;10^{\circ}C,\;and\;4^{\circ}C$, respectively. These results clearly suggest that the shelf-life of Chonggak-kimchi depends on storage temperature, and the pH limit for marketing is 4.3; this is a freshness indicator for Chonggak-kimchi.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.430-440
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• 1998

The average number of total viable counts for the commercial pork tested was 19/g, coliform 1.8/g, psychrophilic bacteria 15/g, heterotrophic bacteria 12/g, fecal streptococcus 6.2/100 g, Pseudomonas aeruginosa 13/100 g and none of heat-resistant bacteria and Staphylococcus was detected. That for the commercial beef tested was 130/g, coliform 5.2/g, psychrophile 140/g, heterotroph 28/g, Staphylococcus 1.2/g, fecal streptococcus 9.5/100 g, Pseud. aeruginosa 1.9/100 g and heat-resistant bacteria was not detected. That for the commercial chicken tested was 8800/g, coliform 53/g, psychrophile 4600/g, heterotroph 4700/g, fecal streptococcus 9.9/100 g, Pseudo aeruginosa 2.5/100 g. That for milk was 4700/ml, psychrophile 120/ml, heterotroph 420/ml and the others were not detected. That for the commercial cheese was 3.2/g, psychrophile 2.3/g, heterotroph 1.6/g, Staphylococcus l/g, fecal streptococcus 9.1/g. That for fermented milk was $10^{7}/ml$, heatresistant bacteria $10^{6}/ml$, fecal streptococcus 2400/100 ml, lactobacillus $3.2{\times}10^{15}/ml$, in accordance with lactic acid bacteria and the others were not detected. There was not detected any indicator organisms from ham, sausage, butter, eggs and quails in the commercial fooods tested. SPC, coliform, psychrophile and heterotroph in commercial meats stored at $10^{\circ}C$ were increased rapidly as time goes on but heat-resistant bacteria, staphylococcus, fecal streptococcus and Pseudo aeruginosa were constant. At $20^{\circ}C$, SPC, coliform, psychrophile, heterotroph and fecal streptococcus were the highest at 7 days and heat-resistant bacteria, staphylococcus and Pseudo aeruginosa were increased a little. At $30^{\circ}C$, all indicators were increased rapidly for 3 and 7 days and then decreased rapidly. All indicator organisms were increased at the level of 10/g for 14 days in meat products stored at $10^{\circ}C$, but SPC, psychrophile and heterotroph in meat products stored at $20^{\circ}C$ were increased at the level of $lO^5/g$. It showed that the indicators in meat products stored at $30^{\circ}C$ had a tendency to increase at the level of $10^{2}/g$ relative to those stored at $20^{\circ}C$. SPC, psychrophile and heterotroph in milk stored at $10^{\circ}C$ increased up to the level of $10^4/ml$, but coliform, staphylococcus, fecal streptococcus and Pseudo aeruginosa were not detected. As stored at $20^{\circ}C$ and $30^{\circ}C$, they were increased rapidly for 1 or 3 days and then constant for a long time.

• Food Science of Animal Resources
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• v.31 no.3
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• pp.405-412
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• 2011

The purpose of this study was to isolate and characterize bacteriocin-producing bacteria against Clostridium perfringens from domestic animals to determine their usefulness as probiotics. The feces of cattle and chicken were used as sources to isolate bacteriocin-producing bacteria using the spot-on-lawn method. In total, 900 bacterial stains were isolated from domestic animal feces, and 19 strains were finally selected after determining the inhibitory activity against the pathogenic indicator C. perfringens KCTC 3269. Eighteen strains of Bacillus subtilis and one strain of Brevibacillus parabrevis were identified by 16s rRNA sequencing. Most of the bacterial strains isolated were resistant to 0.5% bile salts and remained viable after 2 h at pH 3.0. Additionally, some B. subtilis strains showed strong inhibitory activity against Listeria monocytogenes. We isolated and screened B. subtilis strains CB 153 and CB 189 from cattle and B. subtilis MSC 156 and B. parabrevis MSC 164 from chickens using probiotic selection criteria such as inhibition activity against C. perfringens and tolerance to acid and bile salts. The isolated bacteriocin-producing bacteria and/or bacteriocin have the potential to be used as probiotics in the livestock industry.

• Biomedical Science Letters
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• v.27 no.4
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• pp.310-316
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• 2021

Mobile phones used by healthcare workers are not only an indicator of the contamination of healthcare associated bacteria, but can also be another source of infection. The number and time of handwashing, mobile phone operation time and disinfection were highly relation with the bacterial contamination on the surface of mobile phone. Healthcare associated bacteria isolated from the mobile phone surface were 28 MRCoNS (48.3%), 14 S. aureus (24.2%), 3 MRSA (5.2%), 5 A. baumannii (8.6%), 3 MRAB (5.2%), 3 Entrococcus spp. (5.1%), 2 Pantoea spp. (3.4%), 2 A. lowffii (3.4%), 1 E. cloacae (1.7%), 1 P. stutzeri (1.7%), and P. mirabillis (1.7%). For isolation according to department, 2 MRAB from the emergency room and 1 MRSA from intensive unit, the radiology team and the rehabilitation medical team, respectively were isolated. As a result of the relation of isolates from the department of patient contact (ER, RT, GW, CP, ICU, RMT), the bacterial isolation rate was 75% and the department of patient non-contact (MRT) was 10%.

• Biomedical Science Letters
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• v.22 no.4
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• pp.167-173
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• 2016

The broth microdilution technique used to measure the minimal inhibitory concentration (MIC) of natural compounds against bacteria is problematic: it is difficult to visualize bacterial growth due to the color of the natural compound. Therefore, the use of a colorimetric method with a redox indicator by broth microdilution can simplify it and increase its objectivity. This study evaluated the usefulness of the colorimetric method in measuring the MIC of Phellinus baumii against methicillin-resistant Staphylococcus aureus (MRSA). The inhibition in disc diffusion method was observed from $8,192{\mu}g/mL$ P. baumii in all 10 MRSA isolates examined; however, the MIC ranges of the 10 MRSA isolates was $512{\sim}2,048{\mu}g/mL$ by broth microdilution using a colorimetric method; with the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) indicator. In addition, the MIC of P. baumii by broth microdilution using MTT as indicator yielded excellent results. However, the 2, 3, 5-triphenyltetrazolium chloride (TTC) results could not be determined due to the color of the TTC indicator. The MICs of four antibiotics against MRSA using MTT or TTC were equal to those determined by visual interpretation. In conclusion, to evaluate the antibacterial effects of a natural compound, the broth microdilution technique is considered to be better than the disc diffusion method. Moreover, to resolve the problems caused by the colors of natural compounds, a colorimetric method such as that using MTT may be very valuable.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1237-1245
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• 2018

In this study, the contamination levels of hygienic indicators and foodborne pathogens in retail meat products were investigated in relation to the various market factors including processing temperature, processing area, and market type. Ground beef samples (n=80) were purchased from 40 meat markets and investigated for microbiological quality. Beefs processed below $20^{\circ}C$ had significantly lower numbers of total coliforms (TC) than these processed over $20^{\circ}C$ (2.01 vs. 2.79 log CFU/g; p<0.05). Interestingly, separation of processing area did not affect the contamination levels. Remarkably, the contamination levels of hygienic indicator differ among market types, indicating that not only processing condition but distribution structure that is directly related with storage period could affect the final microbiological loads of the meat products. In addition, the prevalences of Listeria monocytogenes (a psychrotroph), Enterococcus faecium, and Enterococcus faecalis were 7.5% (6/80), 10.0% (8/80), and 20.0% (16/80), respectively, which is irrelevant to market factors except meat products from wholesale markets where no L. monocytogenes were found among 30 samples. The results of this study indicate that the contamination level of hygiene indicator and foodborne pathogens in retail beef is more related with processing temperature and storage period than other environmental factors.