• Journal of Ginseng Research
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• 제39권4호
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• pp.392-397
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• 2015

Background: Red ginseng (RG) is processed from Panax ginseng via several methods including heat treatment, mild acid hydrolysis, and microbial conversion to transform the major ginsenosides into minor ginsenosides, which have greater pharmaceutical activities. During the fermentation process using microbial strains in a machine for making red ginseng, a change of composition occurs after heating. Therefore, we confirmed that fermentation had occurred using only microbial strains and evaluated the changes in the ginsenosides and their chemical composition. Methods: To confirm the fermentation by microbial strains, the fermented red ginseng was made with microbial strains (w-FRG) or without microbial strains (n-FRG), and the fermentation process was performed to tertiary fermentation. The changes in the ginsenoside composition of the self-manufactured FRG using the machine were evaluated using HPLC, and the 20 ginsenosides were analyzed. Additionally, we investigated changes of the reducing sugar and polyphenol contents during fermentation process. Results: In the fermentation process, ginsenosides Re, Rg1, and Rb1 decreased but ginsenosides Rh1, F2, Rg3, and Compound Y (C.Y) increased in primary FRG more than in the raw ginseng and RG. The content of phenolic compounds was high in FRG and the highest in the tertiary w-FRG. Moreover, the reducing sugar content was approximately three times higher in the tertiary w-FRG than in the other n-FRG. Conclusion: As the results indicate, we confirmed the changes in the ginsenoside content and the role of microbial strains in the fermentation process.

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1195-1206
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• 2020

Beringraja pulchra, Cham-hong-eo in Korean, is a mottled skate which is belonging to the cartilaginous fish. Although this species is economically valuable in South Korea as an alkaline-fermented food, there are few microbial studies on such fermentation. Here, we analyzed microbial changes and pH before, during, and after fermentation and examined the effect of inoculation by a skin microbiota mixture on the skate fermentation (control vs. treatment). To analyze microbial community, the V4 regions of bacterial 16S rRNA genes from the skates were amplified, sequenced and analyzed. During the skate fermentation, pH and total number of marine bacteria increased in both groups, while microbial diversity decreased after fermentation. Pseudomonas, which was predominant in the initial skate, declined by fermentation (Day 0: 11.39 ± 5.52%; Day 20: 0.61 ± 0.9%), while the abundance of Pseudoalteromonas increased dramatically (Day 0: 1.42 ± 0.41%; Day 20: 64.92 ± 24.15%). From our co-occurrence analysis, the Pseudoalteromonas was positively correlated with Aerococcaceae (r = 0.638) and Moraxella (r = 0.474), which also increased with fermentation, and negatively correlated with Pseudomonas (r = -0.847) during fermentation. There are no critically significant differences between control and treatment. These results revealed that the alkaline fermentation of skates dramatically changed the microbiota, but the initial inoculation by a skin microbiota mixture didn't show critical changes in the final microbial community. Our results extended understanding of microbial interactions and provided the new insights of microbial changes during alkaline fermentation.

• 한국농림기상학회지
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• 제9권3호
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• pp.161-169
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• 2007

대기 중 이산화탄소 농도 및 온도 증가와 강수 패턴 변화에 따른 가뭄 정도 및 횟수의 변화는 습지에서 발생하는 온실가스의 양에 영향을 미칠 수 있다. 습지에 존재하는 다양한 미생물 군집(탈질세균 및 메탄생성세균) 이 온실가스 생성에 있어 중요한 역할을 감당한다. 본 논문은 지금까지 전지구적 기후변화가 습지에서의 온실가스 발생과 관련 미생물 군집에 미치는 영향에 관한 다양한 연구를 정리하는 데 그 목적이 있다. 대기 중 이산화탄소 농도와 기온 증가는 일반적으로 온실가스 생성을 증가시켰다. 반면, 가뭄의 영향은 기체 종류와 가뭄 정도에 따라 다양한 결과가 보고되었다. 기후변화에 따른 미생물 군집의 변화는 습지시스템에서 보고된 연구의 부족으로 인해 특정한 결론을 도출할 수 없었다. 본 총설은 습지에서 미생물을 매개로 한 반응을 연구함에 있어 관련 미생물 군집구조의 특성을 파악하고, 다양한 환경인자에 대한 그들의 반응을 알아내는 것과 미생물 반응과 군집구조간의 상관 관계를 도출하는 것의 중요성을 제안한다. 이는 향후 전지구적 기후 변화가 습지의 생태학적 기능에 미칠 영향을 더 잘 이해하고 예측하는데 있어 매우 중요할 것이라 사료된다.

• The Plant Pathology Journal
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• 제40권5호
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• pp.498-511
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• 2024

Bacterial wilt caused by Ralstonia solanacearum is a destructive disease that affects potato production, leading to severe yield losses. Currently, little is known about the changes in the assembly and functional adaptation of potato rhizosphere microbial communities during different stages of R. solanacearum infection. In this study, using amplicon and metagenomic sequencing approaches, we analyzed the changes in the composition and functions of bacterial and fungal communities in the potato rhizosphere across four stages of R. solanacearum infection. The results showed that R. solanacearum infection led to significant changes in the composition and functions of bacterial and fungal communities in the potato rhizosphere, with various microbial properties (including α,β-diversity, species composition, and community ecological functions) all being driven by R. solanacearum infection. The relative abundance of some beneficial microorganisms in the potato rhizosphere, including Firmicutes, Bacillus, Pseudomonas, and Mortierella, decreased as the duration of infection increased. Moreover, the related microbial communities played a significant role in basic metabolism and signal transduction; however, the functions involved in soil C, N, and P transformation weakened. This study provides new insights into the dynamic changes in the composition and functions of potato rhizosphere microbial communities at different stages of R. solanacearum infection to adapt to the growth promotion or disease suppression strategies of host plants, which may provide guidance for formulating future strategies to regulate microbial communities for the integrated control of soil-borne plant diseases.

• 한국토양비료학회지
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• 제44권1호
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• pp.127-145
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• 2011

Various environmental ecosystems are valuable sources for microbial ecology studies, and their analyses using recently developed molecular ecological approaches have drawn significant attention within the scientific community. Changes in the microbial community structures due to various anthropogenic activities can be evaluated by various culture-independent methods e.g. ARISA, DGGE, SSCP, T-RFLP, clone library, pyrosequencing, etc. Direct amplification of total community DNA and amplification of most conserved region (16S rRNA) are common initial steps, followed by either fingerprinting or sequencing analysis. Fingerprinting methods are relatively quicker than sequencing analysis in evaluating the changes in the microbial community. Being an efficient, sensitive and time- and cost effective method, T-RFLP is regularly used by many researchers to access the microbial diversity. Among various fingerprinting methods T-RFLP became an important tool in studying the microbial community structure because of its sensitivity and reproducibility. In this present review, we will discuss the important developments in T-RFLP methodology to distinguish the total microbial diversity and community composition in the various ecosystems.

• 한국식품저장유통학회:학술대회논문집
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• 한국식품저장유통학회 2003년도 제23차 추계총회 및 국제학술심포지움
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• pp.188.1-188
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• 2003

To examine the effect of vacuum packaging on the quality of chicken during storage, microbial (total bacterial counts, mold and yeast, E. coli, and Pseudomonas) changes and drip loss were determined. fresh chicken breasts were prepared and packaged using polyethylene film under vacuum and normal atmosphere, respectively. Samples were then stored at 4$^{\circ}C$ for two weeks. At various time intervals during storage, sample was taken homogenized, and diluted with 0.1% sterile peptone water, and followed by microbial counts. Microbial changes of total bacterial counts, mold and yeast, E. coli, and Pseudomonas during storage of chicken were significantly decreased by vacuum packaging. Drip loss was also significantly decreased. These results indicate that vacuum packaging of chicken should be recommended as a suitable storage method in terms of microbial safety as well as quality of chicken.

• The Plant Pathology Journal
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• 제38권6호
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• pp.692-699
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• 2022

Bacterial wilt caused by Ralstonia solanacearum is considered one of the most harmful diseases of pepper plants. Recently, research on plant disease control through the rhizosphere microbiome has been actively conducted. In this study, the relationship with disease occurrence between the neighboring plant confirmed by analyzing the physicochemical properties of the rhizosphere soil and changes in the microbial community. The results confirmed that the microbial community changes significantly depending on the organic matters, P₂O₅, and clay in the soil. Despite significant differences in microbial communities according to soil composition, Actinobacteriota at the phylum level was higher in healthy plant rhizosphere (mean of relative abundance, D: 8.05 ± 1.13; H: 10.06 ± 1.59). These results suggest that Actinobacteriota may be associated with bacterial wilt disease. In this study, we present basic information for constructing of healthy soil in the future by presenting the major microbial groups that can suppress bacterial wilt.

• Journal of Ecology and Environment
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• 제34권4호
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• pp.401-410
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• 2011

We assayed the effects of simulated acid rain on the mass loss, $CO_2$ evolution, dehydrogenase activity, and microbial biomass-C of decomposing Sorbus alnifolia leaf litter at the microcosm. The dilute sulfuric acid solution composed the simulated acid rain, and the microcosm decomposition experiment was performed at 23$^{\circ}C$ and 40% humidity. During the early decomposition stage, decomposition rate of S. alnifolia leaf litter, and microbial biomass, $CO_2$ evolution and dehydrogenase activity were inhibited at a lower pH; however, during the late decomposition stage, these characteristics were not affected by pH level. The fungal component of the microbial community was conspicuous at lower pH levels and at the late decomposition stage. Conversely, the bacterial community was most evident during the initial decomposition phase and was especially dominant at higher pH levels. These changes in microbial community structure resulting from changes in microcosm acidity suggest that pH is an important aspect in the maintenance of the decomposition process. Litter decomposition exhibited a positive, linear relationship with both microbial respiration and microbial biomass. Fungal biomass exhibited a significant, positive relationship with $CO_2$ evolution from the decaying litter. Acid rain had a significant effect on microbial biomass and microbial community structure according to acid tolerance of each microbial species. Fungal biomass and decomposition activities were not only more important at a low pH than at a high pH but also fungal activity, such as $CO_2$ evolution, was closely related with litter decomposition rate.

• Food Science and Biotechnology
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• 제27권6호
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• pp.1865-1869
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• 2018

This study examined the effects of alfalfa seed germination on growth of Salmonella enterica. We investigated the population changes of S. enterica during early sprout development. We found that the population density of S. enterica, which was inoculated on alfalfa seeds was increased during sprout development under all experimental temperatures, whereas a significant reduction was observed when S. enterica was inoculated on fully germinated sprouts. To establish a model for predicting S. enterica growth during alfalfa sprout development, the kinetic growth data under isothermal conditions were collected and evaluated based on Baranyi model as a primary model for growth data. To elucidate the influence of temperature on S. enterica growth rates, three secondary models were compared and found that the Arrhenius-type model was more suitable than others. We believe that our model can be utilized to predict S. enterica behavior in alfalfa sprout and to conduct microbial risk assessments.

• Preventive Nutrition and Food Science
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• 제6권4호
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• pp.240-243
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• 2001

Fresh pasta was packaged in a modified atmosphere of 22% $CO_2$/78% $N_2$ and compared with a control air package for its quality changes during storage at 8$^{\circ}C$. The modified atmosphere packaging suppressed the microbial growth of total aerobic bacteria and yeasts/molds with a concomitant reduction in the rates of physical and chemical quality changes, and thus successfully extended the shelf life of fresh packs from 20 days of air packs to 40 days based on microbial criterion of 10$^{6}$ cfu/g. The shelf life extension was greater when the initial microbial quality of the product was better.