• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.727-734
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• 2013

Makgeolli mashes that were brewed using five different commercial nuruks (fermentation starters) were investigated for changes in physicochemistry, microbial diversity, and biogenic amine (BA) production. Mash A brewed with the nuruk (Gaeryang-nuruk) had the highest level of alcohol concentration and the greatest number of yeast cells, whereas mash E had the greatest number of bacterial cells. Only three biogenic amines were detected in the makgeolli mashes: tyramine, putrescine, and cadaverine. Using a PCR-DGGE technique, we observed that mash E had the highest BA production, and had the greatest number of bands on the denaturing gradient gels. We also observed that the numbers of bacterial cells correlated significantly with the putrescine and the total BA content, and that the BA content correlated significantly with the color values (L, a, b). This study shows that the quality of a makgeolli can depend on the type of nuruk. Therefore, we suggest that the quality management of makgeolli should start with the stage of nuruk manufacture.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.106-112
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• 2007

Ammonia oxidizing bacteria(AOB) oxidize ammonia to nitrite and are important microorganisms which control nitrification. Several environmental factors such as dissolved oxygen(DO), temperature and pH influence the growth of AOB. In this work, to assess the effect of DO concentration on AOB, four aerobic biofilm reactors packed with ceramic media were operated 1, 3, 5 and 7 mgDO/L, respectively. The optimal DO concentration with stable nitrification efficiency in aerobic biofilm reactor was above 5.0 mg/L. To assess the relationship between the DO concentration and the characteristics of AOB in aerobic biofiim reactor, DGGE and cloning based on PCR targeting 16S rRNA and amoA gene were performed. Additionally, INT-DHA activity test was proceeded to estimate the activity of AOB. As the results of DGCE and cloning, the community of AOB and the ratio of Nitrosomonas sp. changed little in spite of different nitrification efficiencies. INT-DHA activity test showed that the activity of AOB decreased as DO concentration decreased. It means that DO concentration does not affect the community of AOB, but the activity of AOB.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.23-32
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• 2010

The capacity of natural purification was limited by the interruption of natural flow and the problems such as eutrophication were occurred by nutritive salts accumulation in stagnant stream. Moreover, the inflow of non-point sources causes non-degradable materials to increase in stagnant stream. In this study, an upflow biological activated carbon (BAC) biofilm process comprised of anoxic, aerobic 1, and aerobic 2 reactors were introduced for treatment of stagnant stream and SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN, and TP were monitored in the upflow BAC biofilm reactors with continuous cycling. In order to simulate stagnant stream, the lake water of amusement park and golf course were stored as influent in a tank of $2m^3$ and hydraulic retention time (HRT) was changed into 6, 4, and 2 hours. At HRT 4hr and the lake water of amusement park as influent, the removal efficiencies of SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN, and TP showed the best water quality improvement and were 69.8, 83.0, 91.3, 74.1, 74.7, and 88.9%, respectively. At HRT 4hr and the lake water of golf course as influent, the removal efficiencies of SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN and TP were 78.5, 78.0, 80.2, 74.9, 55.6 and 97.5%, respectively. As the results of polymerase chain reaction - denaturing gel gradient electrophoresis (PCR-DGGE), microbial community was different depending on influent type. Fluorescence in situ hybridization (FISH) showed that nitrifying bacteria was dominant at HRT 4 hr. The biomass amount and microbial activities by INT-DHA test were not decrease even at lower HRT condition. In this study, the upflow BAC biofilm process would be considered to the water quality improvement of stagnant stream.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.509-516
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• 2010

This study investigates characteristics of diesel degradation and variations of microbial community with the soil enrichment cultures. The cultures has yellow(YE-5) and transparent color's(WH-5) colony on solid plate medium. The bacillus type of YE-5 and WH-5 cultures showed diesel degradation at the rate of 99.07mg-Diesel/$L{\cdot}day$ and 57.82mg-Diesel/$L{\cdot}day$ in the presence of 1%(v/v) initial diesel concentration. Diesel degradation was 1.7 times faster than WH-5 culture. YE-5 or WH-5 culture could degrade a wide range of diesel compounds from $C_8$ to $C_24$. Microbial community analysis by PCR-DGGE technique shows that Psedomonas, Klebsiella, Escherichia and Stenotrophomonas as proteobacteria take role on the diesel degradation. uncultured Senotrophomonas sp. was only detected with YE-5 culture. It is concluded that proper combination of the microorganism should be present to stimulate the degradation of diesel and further studies are recommended for the effect of uncultured Senotrophomonas sp. or Escherichia hermannii on diesel degradation.

• Korean Journal of Food Science and Technology
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• v.46 no.1
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• pp.115-120
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• 2014

The purpose of this study was to develop a rice straw-derived Bacillus cereus (B. cereus)-free starter culture for traditional soybean fermented products using a B. cereus-specific bacteriophage, BCP8-2. To determine the optimal medium that supports the growth of rice straw-derived microorganisms and BCP8-2 activity, 5 different culture media were tested. The 5% ground bean (GB) medium was selected for further study. No B. cereus was detected in the BCP8-2-treated rice straw in GB medium, whereas B. cereus at a level of $10^7$ CFU/mL was recovered in the no-phage control. The total bacterial count reached approximately $10^9$ CFU/mL regardless of phage addition. When the 16S rRNA sequence-based microbial community was monitored using denaturing gradient gel electrophoresis (DGGE) and pyrosequencing, a similar microbial community was observed in the phage-treated and control samples. In conclusion, we demonstrate that phage can be used to prepare a rice straw-derived B. cereus-free starter culture with minimal effect on natural microflora.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.7
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• pp.1115-1124
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• 2013

The present study was conducted to ensure the diversity of domestic solar salt by analyzing the composition and microbiological characteristics of solar salt (from Docho island: DS) and the flower of salt produced in different Korean salt flats (Sinui island: SF, Bigum island: BF, and Docho island: DF). The analyses showed that the moisture content of the three types of flower of salt and solar salt ranged from 10.54~13.82% and NaCl content ranged from 78.81~84.61%. The mineral content of those salts ranged from 3.57~5.51%. The content of insoluble matter in these salts was $0.01{\pm}0.00{\sim}0.05{\pm}0.00%$. The sand content of these salts was $0.01{\pm}0.01{\sim}0.03{\pm}0.01%$. By Hunter's color value analysis, the color of the flower of salt was brighter and whiter than solar salt. The salinity of the flower of salt was a little higher than solar salt as well. The magnesium and potassium ion content of DF was $9,886.72{\pm}104.78mg/kg$ and $2,975.23{\pm}79.73mg/kg$, respectively, which was lower than the content in SF, BF, and DS. The heavy metal content of all salts was acceptable under the Korean Food Sanitation Law. The flower of salt was confirmed to be sweeter and preferable to solar salt. More than 80% of the solar salt crystals were 2~3 mm in size, whereas crystals from the flower of salt were 0.5~2 mm in size. The bacterial diversity of DF and DS were investigated by culture and denaturing gradient gel electrophoresis (DGGE) methods. The number of cultured bacteria in flower of salt was approximately three times more than solar salt. By DGGE analysis, major microbes of DF were Maritimibacter sp., Cupriavidus sp., and unculturable bacteria, and those of DS were Cupriavidus sp., Dunalidella salina and unculturable bacteria. The results of DGGE analysis showed that major microorganisms in solar salts were composed of unidentified and unculturable bacteria and only a few microorganisms were culturable.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.119-125
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• 2009

To understand the ecological function of heterotrophic bacterial community in water column of large freshwater lakes in the permafrost zone, we investigated the structure and function of bacterial community in Lake Khuvsgul, Mongolia. Species composition of overall bacterial community was analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments, and bacteria that can be cultured at 10oC were isolated and characterized. Based on the depth profile of environmental parameters, thermocline and chemocline were recognized at the 5~10 m zone of the water column. The stratified DGGE profile indicated that the discontinuity of water properties might influence the structure of bacterial community: band profiles in the 0~5 m zone were diverse with large change by depth, but the profile was relatively stable at the $\geq$10 m zone, with predominance of the band identified as Acidovorax facilis. Bacterial cultures were screened for protease, cellulase, amylase and lipase activity, and 23 isolates were selected for high activity of the hydrolytic enzymes. The isolates were identified based on their 16S rRNA gene sequences. In the surface water (zero meter depth), Acidovorax defluvii and Sphingobacterium faecium with high cellulase activity were present. Flavobacterium succinicans, Mycoplana bullata and A. facilis were stably predominant isolates at 2 m, 5 m, and $\geq$10 m depths, respectively. F. succinicans isolates showed high protease activity while M. bullata isolates showed moderate levels of protease and celluase activity. A. facilis isolates showed either cellulase or lipase activity, exclusively to each other. According to the profile of growth rates of the isolates in the temperature range of $0\sim42^{\circ}C$, the surface-zone (0~5 m) isolates were facultative psychrophiles while isolates from $\geq$10 m depth were typical mesophiles. This stratification is believed to be due to stratified availability of organic materials to the bacterial decomposers. In the water column below the chemoline, the environment is extremely oligotrophic so that the trait of rapid growth in low temperature might not be demanded by deep-lake decomposers. The stratified distribution of community composition and decomposer activity in Lake Khuvsgul implies that ecological functions of bacterial community in lakes of cold region are sharply divided by water column stratification.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.829-835
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• 2012

The cultivation of genetically modified (GM) crops has increased due to their economic and agronomic advantages. Before commercialization of GM crops, however, we must assess the potential risks of GM crops on human health and environment. The aim of this study was to investigate the possible impact of Bt rice on the soil microbial community. Microbial communities were isolated from the rhizosphere soil cultivated with Bt rice and Nakdong, parental cultivar and were subjected to be analyzed using both culture-dependent and molecular methods. The total counts of bacteria, fungi, and actinomycetes in the rhizosphere of transgenic and conventional rice were not significantly different. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes revealed that the bacterial community structures during cultural periods were very similar each other. Analysis of dominant isolates in the rhizosphere cultivated with Bt and Nakdong rice showed that the dominant isolates from the soil of Bt rice and Nakdong belonged to the Proteobacteria, Cloroflexi, Actinobacteria, Firmicutes, and Acidobacteria. These results indicate that the Bt rice has no significant impact on the soil microbial communities during cultivation period. Further study remains to be investigated whether the residue of Bt rice effect on the soil environment.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.317-325
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• 2008

Recently there are difficulties in management of golf courses because of an ever increasing demand for golf as a leisure sports. Hence natural minerals as an amendment could be applied to improve and manage the physicochemical properties of the golf course soils in an environment-friendly way. In this study, quartz porphyry, which has been shown to be a good soil amendment for crop production, was tested for its effect on physicochemical properties of the golf course soil, growth of creeping bentgrass (Agrostis stolonifera) and changes of soil microbial communities in the soil. In general, amendment of 20% quartz porphyry into the soil turned out to be most effective in enhancing a proper growth of the grass leaves and roots. DGGE profile data showed that eubacterial species richness was also the highest at this level of the mineral treatment in which Actinobacteria and ${\alpha}$-Proteobacteria were the dominant phyla. This appeared to be attributed to a low level of soluble organic matter content and decreased concentration of cations such as $Ca^{2+}$, $Mg^{2+}$, and $K^+$.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.100-107
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• 2000

In a recently developed strategy for in-situ treatment of polychlorinated biphenyls (PCB), bioaugmentation was used in conjunction with a surfactant, sorbitan trioleate, as a carbon source for the degrader bacteria, along with the monoterpene, carvone, and salicylic acid as inducing substrates. Two bacteria were used for soil inoculants, including Arthrobacter sp. st. B1B and Ralstonia eutrophus H850. This methodology achieved 60% degradation of PCBs in Aroclor 1242 after 18 weeks in soils receiving 34 repeated applications of the degrader bacteria. However, an obvious limitation was the requirement for soil mixing after every soil inoculation. In the research reported here, bioaugmentation and biostimulation treatment strategies were modified by using the earthworm, Pheretima hawayana, as a vector for dispersal and mixing of surface-applied PCB-degrading bacteria and soil chemical amendments. Changes in microbial biomass and microbial community structure due to earthworm effects were examined using DNA extraction and PCR-DGGE of 16S rDNA. Results showed that earthworms effectively promoted biodegradation of PCBs in bioaugmented soils to the same extent previously achieved using physical soil mixing, and had a lesser, but significant effect in promoting PCB biodegradation in biostimulated soils treated with carvone and salicylic acid. The effects of earthworms were speculated to involve many interacting factors including increased bacterial transport to lower soil depths, improved soil aeration, and enhanced microbial activity and diversity.