• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.122-128
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• 2008

We evaluated the relationship between the multiplication of heterotrophic microorganisms and physicochemical factors in the final discharged sewage water from J municipal waste water treatment plants. Dissolved organic carbon (DOC) was the most crucial factor influencing multiplication of heterotrophic plate counts (HPC) among the water quality variables selected. Degrading bacteria, such as proteolytic bacteria, lipholytic bacteria, starch degrading bacteria, cellulolytic bacteria, and pectinolytic bacteria, were monitored to understand the condition of nutrients in finished sewage effluent. The percentages of lipid and protein combined occupied 81% in finished sewage water. The multiplication of HPC showed the highest value in August. The formation of trihalomethane (THM) was low in the finished discharge water during chlorine disinfection, which was $71{\mu}/L$ (which was less than $100{\mu}/L$- the standard of drinking water quality) with 10 mg/L of chlorine during 15 min.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.98-102
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• 2015

Oleanolic acid and its derivatives are pentacyclic triterpene acids, which are produced in many plants and herbs. These are considered safe and thus, oleanolic acid is now used for cosmetic and pharmaceutical industry. Oleanolic acid affects peptidoglycan in cell wall of bacteria. Hence, the antimicrobial activity of oleanolic acid is not very obvious to Gram-negative bacteria such as Escherichia coli, Yersinia enterocolitica, Shigella flexneri, and Shigella sonnei because the peptidoglycan is covered with outer membrane. However, oleanolic acid derivatives showed improved antimicrobial activity to Gram-negative bacteria. For Gram-positive bacteria such as Staphylococcus aureus and Listeria monocytogenes, oleanolic acid was very effective on reducing the cell counts of the pathogens. In addition, the cytotoxicity of oleanolic acid for human cell lines was minimal. Therefore, oleanolic acid should be considered as an antimicrobial food additive and a therapeutic agent to control foodborne pathogens.

• Food Science of Animal Resources
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• v.34 no.4
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• pp.543-551
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• 2014

The aim of this study was to evaluate the effect of proteolytic (Serratia liquefaciens, match %: 99.39) or lipolytic (Acinetobacter genomospecies 10, match %: 99.90) psychrotrophic bacteria (bacterial counts, analysis of free fatty acids (FFA) and analysis of free amino acids) on the microbial and chemical properties (yogurt composition), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of yogurt during storage. Yogurts were prepared with raw milk preinoculated with each psychrotrophic bacteria. The total solid, fat, and protein content were not affected by preinoculation, but the pH of yogurt preinoculated with psychrotrophic bacteria was higher than in control. There was a dramatic increase in short chain free fatty acids among FFA in yogurt with Acinetobacter genomospecies 10. For 14 d of cold storage condition, SCFFA was 25.3 mg/kg to 34.4 mg/kg (1.36 times increased), MCFFA was 20.4 mg/kg to 25.7 mg/kg (1.26 times increased), and LCFFA was 240.2 mg/kg to 322.8 mg/kg (1.34 times increased). Serratia liquefaciens (match %: 99.39) in yogurt caused a greater accumulation of free amino acids (FAA), especially bitter peptides such as leucine, valine, arginine, and tyrosine, but SDS-PAGE showed that the inoculation of Serratia liquefaciens did not affect the degree of casein degradation during storage. Taken together, the excessive peptides and FFA in yogurt generated from psychrotrophic bacteria could develop off-flavors that degrade the quality of commercial yogurt products.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.365-365
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• 2017

Yogurt is a food produced by bacterial fermentation of milk and the bacteria used to make it are known as "yogurt cultures". Most of them belong to probiotics such as Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus bacteria. Domestic fermented milk market is increasing and about 30 companies are producing yogurt. The purpose of this study was to analyze the quality characteristics of domestic commercial semisolid type yogurt. We collected 20 types of commercial yogurt at local markets. Physicochemical properties including pH, sugar content, acidity, viscosity and microbial characteristics of lactic acid bacteria counts were measured. The yogurt showed pH 4.5, 7.4~18.1% of sugar contents, 0.6~1.3% of total acids and 282~748 cP of viscosities. In the microorganism populations, lactic acid bacteria count were 6.5~11.5 Log CFU/mL and anaerobic lactic acid bacteria count were 7.2 ~ 11.1 Log CFU/mL. The quality characteristics were different depending on the constituents of the sample and the microorganisms used. These results are related to the quality characteristics of yogurts which are useful information about identifying new trends in domestic fermented milk industry.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.450-455
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• 2018

We examined correlations of the density of fish farms with the distributions of indicator bacteria (Escherichia coli, fecal streptococci) and a bacterial fish pathogen (Streptococcus parauberis) off the coastline of Jeju Island. Seawater samples were collected at four coastal sites on the Island [Aewol (control), Gujwa, Pyoseon and Daejeong] in June, August and October 2016. The indicator bacteria were generally more frequently isolated from samples taken in August when water temperatures and human activities on nearby beaches were highest. Although fish farms were least common at Daejeong, the numbers of isolated fecal indicator bacteria were highest in the seawater and effluent water collected from this site. Hence, fish farms were not likely major contributors of indicator bacteria at Daejeong. We found discrepancies between the isolated bacterial counts and the predicted bacterial copy numbers deduced from our qPCR results, indicating that this pathogen may exist in a viable but non-culturable (VBNC) state in seawater. Thus, livestock wastewater and chemical fertilizer loading off Jeju Island may negatively impact seawater quality more than the effluent released from fish farms does.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.3
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• pp.421-429
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• 2019

Objective: In this study, the effects of vacuum (VP) and high-oxygen modified atmosphere ($80%\;O_2+20%\;CO_2$) packaging (HiOx-MAP) on physico-chemical and microbiological properties of minced water buffalo meat were investigated. Methods: After minced meat preparation, samples were packaged under VP and HiOx-MAP and stored at $2^{\circ}C{\pm}0.5^{\circ}C$ for 14 days. Samples taken on certain days were subjected to total aerobic mesophilic bacteria, total aerobic psychrotrophic bacteria, lactic acid bacteria, Pseudomonas, Enterobacteriaceae and yeast-mold counts as well as pH, color ($L^*$, $a^*$, and $b^*$) and thiobarbituric acid reactive substances (TBARS) analyses. Results: In minced water buffalo meat packaged under HiOx-MAP, TBARS value exceeded 1 mg malondialdehyde/kg on the 4th day of the storage. In VP samples, TBARS value remained close to initial TBARS value during storage. According to the findings, $a^*$ value was determined to be high in the HiOx-MAP samples within initial days of the storage. However, no significant changes in $a^*$ value were observed in VP samples during storage. In contrast, the mean value of $L^*$ was detected as higher in HiOx-MAP sample than VP samples. The count of psychrotrophic bacteria increased more than that of mesophilic bacteria during storage. The growth of Enterobacteriaceae and Pseudomonas was delayed in both the packaging methods. However, lactic acid bacteria exhibited more growth in VP samples compared to MAP samples. Conclusion: The lipid oxidation proceeded faster than expected in minced water buffalo meat packed with HiOx-MAP method. This situation adversely affected the $a^*$ value. On the other hand, similar microbiological results were obtained in both packing methods.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1623-1629
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• 2014

Dry-cured pork neck samples were stored at $10^{\circ}C$ for 90 days under vacuum packaging (VP) or modified atmosphere packaging (MAP; 25% $CO_2$+75% $N_2$) conditions. The pH, moisture, water activity, total aerobic bacteria, and Enterobacteriaceae counts of dry-cured pork neck products with MAP were significantly lower than those with VP (p<0.05) after 90 days of storage. However, CIE $b^*$ and 2-thiobarbituric acid reacted substance (TBARS) values of the pork product with MAP were significantly higher (p<0.05) than those with VP. Total aerobic bacterial counts and Enterobacteriaceae counts of samples with MAP were lower than those with VP after 30 days of storage. Sensory results indicated that aroma, flavor and tenderness scores of the samples with both VP and MAP decreased during storage and the scores after >60 days of storage were lower than those at Day 1. In conclusion, despite presenting higher lipid oxidation, the samples stored in packages containing 25% $CO_2$ for 90 days at $10^{\circ}C$ have lower bacterial counts than vacuum-packed samples. Therefore, further studies should be performed on the packaging of dry-cured meat at adjusted concentrations of $CO_2$.

• Journal of Korean Biological Nursing Science
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• v.11 no.1
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• pp.92-98
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• 2009

Purpose: This study was aimed to investigate the colony counts by different disinfecting processes and duration of the operation for humidifiers in an intensive care unit (ICU) in Busan. Method: The four steps of disinfecting process were taken with four different humidifiers according to the use of disinfectant (1:100 $Deconex^{(R)}$ 50FF/nothing) and refilling water (tap water/distilled water). First, the colony counts using water sample from wick was conducted at 0 hr, 24 hr, and 48 hr respectively after turning on the humidifiers. Next, the colony counts using waterdrop from the outlet was done at 0 hr, 24 hr, 48 hr, and 72 hr respectively after turning on the humidifiers. Result: No colony was counted after disinfecting with 1:100 $Deconex^{(R)}$ 50FF until 72 hr after turning on the humidifiers. However, without disinfecting with $Deconex^{(R)}$ 50FF, the colony count was increased in the humidifiers from 24 hr after turning on the humidifiers. The result was the same regardless of the refilling water. Conclusion: According to the results, the study found that disinfection of humidifiers in the ICUs with 1:100 $Deconex^{(R)}$ 50FF every 72 hr is effective to remove general bacteria.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.6
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• pp.863-866
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• 2003

This study was conducted to examine the effects of dietary cellulose levels on growth, nitrogen utilization, the retention time of diets in the digestive tract, and caecal microflora of 2-month-old Single Comb White Leghorn male chickens fed 3 purified diets that contained 0, 3.5% and 10% cellulose in equal amount of nutrients for 7 days. Body weight gain and nitrogen utilization were significantly higher (p<0.05), while total microflora counts in the caecal contents and retention time of the diet in the digestive tract were significantly lower (p<0.05) in the group fed 3.5% dietary cellulose compared with the group fed 10% dietary cellulose. Body weight gain, nitrogen utilization and retention time of the diet in the digestive tract decreased significantly while the total microflora count in the caecal contents increased significantly in the group fed 10% dietary cellulose compared to the group fed 0% dietary cellulose (p<0.05). Chickens fed 10% dietary cellulose had significantly increased counts of uric acid-degradative bacteria such as Peptococcaceae and Eubacterium, including Peptostreptococcus (p<0.05). The results suggest that cellulose in purified diets is an effective ingredient and the effects on growth, nitrogen utilization, caecal microflora counts and diet retention time in the digestive tract are dependent on the inclusion rate. Positive or negative effects of dietary cellulose are displayed by growth, nitrogen utilization, caecal microflora counts and retention time of the diet in the digestive tract. Positive effects were displayed when the inclusion rate is 3.5% and negative effects were displayed when that is greater than 3.5% of the diet, and the phenomenon is without reference to the age of the chickens.