• Korean Journal of Environmental Agriculture
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• v.29 no.3
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• pp.287-292
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• 2010

We aimed to investigate the responses of soil organisms to cover plants and to provide information for the selection of proper plant species. We studied the effects of 7 cover plants, including rye, oat, rattail fescue, Chinese milk vetch, red clover, crimson clover, and hairy vetch, on soil organisms in an apple orchard. An increase in the microbial phospholipid fatty acids (PLFA) and in the number of nematodes and microarthropods in the soil under the cover plants reflects elevated activities of soil organisms. A decrease in the level of some marker PLFA, which is an indicator of environmental stress, suggests that cover plants provide favorable environments for soil organisms. The population of fungi and animals that feed on fungi increased in the soil surface under red clover. The population density of nematodes and mites increased in the soil surface under rattail fescue, and that of mites and omnivorous nematodes increased in the soil surface under Chinese milk vetch. The level of microbial PLFA in the soil surfaces under the tested cover plants was higher than that under clean culture system. These results suggest that proper selection of the cover plants can facilitate the creation of favorable environments for soil organisms.

• 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.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.117-124
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• 2016

Researches on soil microbial community are increasing to assess ecosystem responses to anthropogenic disturbances and to provide an indicator of ecosystem recovery. Microbial communities are able to respond more rapidly to environmental changes than plants and therefore they may provide an early indication of the ecosystem recovery trajectory. This study was conducted using 16S rRNA gene pyrosequencing of soil samples to compare soil bacterial community composition between artificially covered soils of the Baedudaegan ridgeline and their adjacent forest soils in two restoration project sites, Ihwaryeong and Yuksimnyeong, which were completed in 2012 and 2013, respectively. Richness of the Phylum level was 29.3 in Ihwaryeong and 32.3 in Yuksimnyeong. Significant difference in the richness between artificial restored soils and adjacent forest soils(p<0.01) was observed, however no significant difference was observed for site location and soil depth. Acidobacteria(37.3%) and Proteobacteria(31.1%) were more abundant than any other phylum in collected soil samples. Also, we found the significant difference in the relative abundance of the two abundant phyla between artificially restored soils and their adjacent forest soils (Proteobacteria, 38.1% in restored soils vs 24.2% in adjacent forest soils, p<0.01; Acidobacteria, 55.4% in restored soils vs 19.2% in adjacent forest soils, p<0.001). The results support the previous researches indicating that soil bacterial community composition is affected by nutritional status of soils and that Acidobacteria is also strongly influenced by pH, thus favoring soils with lower pH. This study could be utilized to monitor and evaluate restoration success of forest soil environment quantitatively.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.551-554
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• 2012

The present laboratory investigation was conducted to assess the effect of heavy metals on carbon mineralization. Soil was treated with three concentrations (50, 100 and $150{\mu}mol\;g^{-1}$ soil) of two heavy metals (Cd and Zn) in a factorial combination of treatments replicated four times. Determination of carbon mineralization was carried out at 3, 7, 14, 21, 28, 42 and 56 days after metal treatments.. The amount of $CO_2$-C released from heavy metal treated soils was found to be decreased at an increasing rate during the first 28 days, followed by slow release as incubation progressed. The total amounts of $CO_2$-C released were 448, 382 and $348mg\;kg^{-1}$ soil respectively for soils treated with 50, 100 and $150{\mu}mol\;g^{-1}$ soil of Zn. The corresponding figures for Cd treated soils were 406, 354 and $282mg\;kg^{-1}$ soil implying that dose-dependent reduction in cumulative $CO_2$-C released from soils. The inhibition of carbon mineralization was found to be high in Cd treated soils than that of Zn treated. Therefore, tolerance and adaptation of the microbial community is likely to be related to the concentration and the type of metal. According to the results, carbon mineralization can be considered as possible indicator of soil pollution by means of heavy metals.

• 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.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.754-762
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• 2012

Colbricon Superiore and Inferiore are two small adjacent high-mountain lakes located in the Paneveggio Natural Park (Italy) that offer the rare opportunity to study two iso-ecologic water environments differing only by area and volume in a ratio of 2:1 and 3:1, respectively. We took advantage of this setting to investigate phytoplankton dynamics, compare variability and productivity differences between the two basins, and assess size-dependent issues. The phytoplankton group of the Dinophyceae was chosen as the indicator organisms of ecological perturbation owing to their high sensitivity to environmental variations, as well as their acknowledged nature of versatile proxy to report global climatic changes. The study was conducted for over 10 years with fortnightly samplings. Results indicated that (a) the Dinophyceae communities in the smaller lake were significantly more resistant to changes exerted by the fluctuation of lakewater transparency and pH; and (b) the smaller lake sustained a consistently higher production with an average Dinophyceae density 1.73 fold higher than that of the larger lake. The coefficients of variation show that the chemical parameters in the smaller lake display higher time-related fluctuation while being spatially homogeneous and that such conditions correlate with a higher stability of the Dinophyceae assemblage. The use of this setting is also proposed as a model to test relationships between ecosystem production and physical stability.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.2
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• pp.121-126
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• 2019

Trimethylamine (TMA) is a nitrogen-based aliphatic organic compound. It is a major odorous component of fish and fishery products and is often used as an indicator of fish quality. The efficacy of TMA removal by various yeast strains was investigated. The five yeast strains found to be most effective in removing TMA were isolated from fermented foods and were identified as Saccharomyces cerevisiae based on biochemical and 18S rRNA sequence analyses. These strains were designated as S. cerevisiae SK1511, SK1512, SK1513, SK1514 and SK1515. Yeast cultures were treated with a TMA solution (0.3%, v/v), and the level of TMA reduction was analyzed by headspace gas chromatography. The five S. cerevisiae strains removed 32.02-50.34% of the TMA from the solution. This study is the first to demonstrate TMA reduction by microbial treatment.

• The Korean Journal of Food & Health Convergence
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• v.5 no.3
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• pp.35-40
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• 2019

In this study, general bacterial counts and coliform counts, which are hygienic indicator microorganisms, were tested for candy, chocolate, and jelly which are easily available and enjoyed around. After dropping each sample on the desk, indoors, and outdoors, it is immediately collected, or washed and collected to confirm the myth of the 3-second rule. Immediately after removing the wrapping paper, each sample was dropped on the desk, indoors, and outdoors, and after 3 seconds from the moment of contact with the surface, and then collected in a sample bag using sterilized sanitary gloves. After the same operation, each sample was rinsed for 5 seconds using sterilized sanitary gloves and sterilized distilled water, and then collected in a sample bag. The number of bacteria detected in non-washing candies was 41 CFU/g at outdoor and the number of bacteria detected in non-washing chocolate was 76 CFU/g at outdoor. The number of bacteria detected in non-washing jellies was 79 CFU/g at outdoor. Coliform group was not detected in all samples. This showed good results at the level of m = 10,000 or less, which is an allowable value suggested in the Food Code. Also, effect of washing on contaminated food was confirmed. This result is remarkably low compared with the microorganism specimens shown in Food Code, and it is confirmed that contamination occurs but not high value. Therefore, the myth of the 3-second rule is true compared to the figures based on Food Code. However, it showed the characteristics of bacteria that could survive and cross-contaminate on dry food surfaces and emphasized the importance of hygiene through food contact to unsanitary surfaces to minimize the risk of food poisoning.

• Journal of the FoodService Safety
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• v.4 no.1
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• pp.7-20
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• 2023

This study was conducted to investigate the impact of refrigerator type and temperature fluctuations on the quality changes of refrigerated foods. Phycochemical and sensory quality, as well as microbial growth, were measured for various foods stored in open- or door-type refrigerators set at 5℃ during storage. The average temperatures recorded were 11.50±1.14℃ in an open refrigerator, and 6.34±0.97℃ in a closed refrigerator. The average surface temperatures of the food items were 9.60±1.20 and 6.00±0.80℃ for open and closed refrigerators, respectively. Significant changes in color and appearance quality were observed in lettuce, mackerel, ground beef, and cut pineapples when stored in open refrigerators. Ready-to-Eat foods such as gimbap and sandwiches exhibited higher levels of microbiological proliferation when stored in open refrigerators compared to closed refrigerators. Processed foods, such as sterilized milk and packaged tofu, did not show significant differences in quality among various types of refrigerators. The installation of refrigerator doors can effectively minimize temperature fluctuations caused by external factors, thereby reducing variations in food quality. These findings provide essential insights into the quality changes associated with the implementation of refrigerator doors, serving as fundamental data for ensuring optimal food preservation.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.49-58
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• 2010

The objectives of this study were to investigate the microbial contamination levels on food service in university and to provide the information of microbial contamination to improve food safety. A total of 288 samples were collected during summer and winter season between 2006 and 2008 from 4 food services located in the university in Western Gyeongnam and were used to detect sanitary indicator bacteria [aerobic plate count (APC), coliform, and Escherichia coli] and pathogenic bacteria (Staphylococcus aureus, Salmonella spp.). As a result, APC and coliform for hand and kitchen utensils which are used often by the employee were detected at high levels of 1.1~5.5 and 1.3~5.3 log CFU/($100\;cm^2$, hand), respectively. The contamination levels of APC and coliform in cooked foods and drinking water were 0.8~6.4 and 1.3~5.0 log CFU/(g, mL), respectively. Especially, the cooked foods showed the highest contamination for APC (2.1~6.4 log CFU/g) and coliform (1.0~5.0 log CFU/g). We think the reason that the cooked foods may be contaminated with APC and coliform on cooking process by using employee's hand and kitchen utensils. Moreover, S. aureus for hand and kitchen utensils was detected at levels of 2.8~3.0 and 2.0~2.3 log CFU/(g, hand), but Salmonella spp. was not detected. According to the above results, contamination levels of the samples were mostly decreased irrespective of summer and winter season. The results obtained indicated that it is necessary to periodic monitoring for microorganism contamination and education about personal and environmental hygiene to employee for ensuring food safety of food service in university.