• Korean Journal of Microbiology
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• v.38 no.2
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• pp.113-118
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• 2002

Laboratory experiments were aimed to evaluate the effect of nitrate as a electron acceptor during the biological phosphorus uptake and to investigate the microbial community. Anaerobic-anoxic sequencing batch reactor (SBR) compared the removal behaviour to anaerobic-oxic SBR, both SBRs maintained lower effluent quality with 1.0 mgp/1. Anaerobic-anoxic SBR was able to remove additional 5.0 to 7.0 mg (P+N)/ι than other biological nutrient removal (BM) system. Therefore, it was proposed that the anaerobic-anoxic SBR was more effective at weak sewage. From the results of the maicrobial community analysis, it can be inferred that denitrifying bacteria and polyphosphate accumulating bacteria coexist in anaerobic-anoxic SBR during stable condition for removing the nitrogen and phosphorus. Particularly, it was suggested that the Zoogloea ramigera in the $\beta$-subclass of proteobacteria and the Alcaligenes defragrans of the Rhodocyclus group in the $\beta$-subclass of proteobacteria played a major role for removing the nitrogen and phosphorus as dPAOs (denitrifying phosphate accumulating organisms).

• Applied Microscopy
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• v.34 no.2
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• pp.103-111
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• 2004

Fresh specimens of the aquatic macrophyte, Spirodela polyrhiza, have been examined employing scanning and transmission electron microscopy. Observations revealed the occurrence of microbial colonization during development. Submerged parts of the small, free-floating S. polyrhiza body exhibited a variety of microorganisms such as bacteria, cyanobacteria, and diatoms throughout their development. However, immature and/or young plants normally demonstrated much less microbial colonization compared to mature plants. During the study, heavy colonization by the microorganisms was routinely encountered at maturity, especially in the fully developed abaxial fronds and root caps. The mucilaginous layer was shown along the root caps, and the microorganisms appeared to be either clustered or attached to this layer. In contrast, only moderate degrees of colonization were observed in the root, and little to no colonization was observable in the adaxial frond surface. Transmission electron microscopy clearly demonstrated the microbial colonization to be external in the S. polyrhiza specimen examined in the current study. The association between the microorganisms and S. polyrhiza has been considered non-harmful, as no frond senescence and almost no mechanical penetration of the plant by the microorganisms were noticed during the study.

• Korean Journal of Poultry Science
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• v.51 no.2
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• pp.73-82
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• 2024

The gut microbiome of broilers is a critical factor in overall health and productivity. However, high summer temperatures and high stocking density (conventional farm condition) may cause stress to broilers, resulting in an imbalance in the gut microbiome. This study was conducted to compare the gut microbiome of broilers between spring and summer in welfare (Bosung, Jeollanam-do, South Korea) and conventional farms (Jangsu, Jeollabuk-do, South Korea). A total of 31 broilers were assigned to the following groups: conventional farm in spring (n = 8); conventional farm in summer (n = 8); welfare farm in spring (n = 7); welfare farm in summer (n = 8). Cecal digesta were collected from eight broilers from each farm, and microbiome analysis was performed using 16S rRNA gene sequencing. Beta diversity analysis indicated clear differences in cecal microbiome composition between spring and summerin both welfare and conventional farm. At the phylum level, analysis of conventional farm revealed a higher proportion of Bacteroidetes in spring than in summer. At the genus level, broilers exhibited a higher abundance of Bacteroides and Alistipesin spring compared to summer. In contrast, the difference in microbial flora composition observed in welfare farm was relatively small compared to conventional farm. In conclusion, the results of this study suggest that heat stress can negatively affect the caecum microbiome of broilers. However, improvements in the housing environment can mitigate the effects of heat stress.

• Journal of Life Science
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• v.31 no.12
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• pp.1079-1087
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• 2021

To analyze gut microbiota of livestock in Korea and compare taxonomic differences, we conducted 16S rRNA metagenomic analysis through next-generation sequencing. Fecal samples from broiler chickens, pigs, and cattle were collected from domestic feedlots randomly. α-diversity results showed that significant differences in estimated species richness estimates (Chao1 and ACE, Abundance-based coverage estimators) and species richness index (OUTs, Operational taxonomic units) were identified among the three groups. However, NPShannon, Shannon, and Simpson indices revealed that abundance and evenness of the species were statistically significant only for poultry (broiler chickens) and mammals (pigs and cattle). Firmicutes was the most predominant phylum in the three groups of fecal samples. Linear discriminant (LDA) effect size (LEfSe) analysis was conducted to reveal the ranking order of abundant taxa in each of the fecal samples. A size-effect over 2.0 on the logarithmic LDA score was used as a discriminative functional biomarker. As shown by the fecal analysis at the genus level, broiler chickens were characterized by the presence of Weissella and Lactobacillus, as well as pigs were characterized by the presence of provetella and cattele were characterized by the presence of Acinetobacter. A permutational multivariate analysis of variance (PERMANOVA) showed that differences of microbial clusters among three groups were significant at the confidence level. (p=0.001). This study provides basic data that could be useful in future research on microorganisms associated with performance growth, as well as in studies on the livestock gut microbiome to increase productivity in the domestic livestock industry.

• the MEAT Journal
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• s.35 winter
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• pp.34-45
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• 2008

People can be exposed to various microorganisms when they eat yukae (seasoned raw meat) because yukae is eaten raw. The purpose of this study was to find out microbial distribution in yukae. In this experiment, 5 restaurants serving yukae were chosen in Daegu area. Mesophilic microorganisms and coliforms were measured by Korean Food Standards Codex. Analyses of Salmonella spp., Listeria monocytogenes, Staphylococcus aureus and Escherichia coli O157:H7 were conducted. As results, mesophilic microorganisms ranged 6.6$\times$103-2.7$\times$105 CFU/g and coliforms ranged 8.9$\times$101-2.1$\times$105 CFU/g. Salmonella spp., Listeria monocytogenes and Escherichia coli O157:H7 were not detected in all 5 samples. However, Staphylococcus aureus was detected in 1 sample out of 5 samples. Hygiene practice during production, processing and cooking process is required.

• Korean Journal of Microbiology
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• v.38 no.2
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• pp.119-126
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• 2002

ATP concentrations far estimating total microbial biomass in the sediment were measured in three different marine sedimentary environments. ATP concentrations were highest in the surface sediment and decreased with increasing sediment depth and distance from the land. The results indicated that the benthic microbial biomass is primarily controlled by nutrient inputs from the overlying water column. Because of the longer residence time and adsorption to the sediment, the variations in organic carbon (OC) contents with sites and depths were not as distinct as that of ATP, and the correlation between OC and ATP was not significant in the coastal sediments. No significant correlation between OC and ATP in the coastal sediments also suggested that microbial biomass in the labile organic-enriched coastal sediment is suppressed by the grazing of higher trophic level such as meiofauna. Overall regional and vertical distribution of ATP indicated that h\`w can be a relevant tool for measuring total microbial biomass in various marine sedimentary environments.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.133-139
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• 2011

In this study, we determined the changes in microbial numbers in solar salts according to the manufacturing process and storage duration. The salt samples were harvested from salt farms in Shinan (area 2) and Yeonggwang (area 1). They were serially diluted ten-fold and then placed on 4 kinds of cultivable media (mannitol salt agar, eosin methylene blue, plate count agar, and trypticase soy agar). After incubation, we obtained 62 halophilic isolates from the salt samples. Coliform and general bacteria were not detected in all salt samples. By 16S rRNA sequencing analysis, we found 12 kinds of halophilic bacteria belonging to the genera Halobacillus, Halomonas, Bacillus, Idiomarina, Marinobacter, Pseudoalteromonas, Vibrio, Salinivibrio, Virgibacillus, Alteromonas, Staphylococcus and some un-known stains. In our study, we discovered two novel species that have a 16S rDNA sequence similarity below 97%.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.187-192
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• 1992

The spatial and temporal distribution of petroleum-degrading bacteria(PDB) was studied at six sampling sites in Kyeonggi Bay of the Yellow Sea fiom March 1990 to October 1991. In addition, petroleum-degrading potcntial of natural ~iiai-ineb acterial population was studied at different culturc contlitions. During the period o f stutly. thc heterotrophic bacterial number and PDB number were n1e;rsured in the range of 7 000-108.400 CFU/nil. 0-2.800 MPN1100 mi. respectively. The spatial tlistribution of PDB wa\ highly affected by presence of petroleum hydrocarbon. In laboratory cxperirncnt. petrolcu~n biodegradation wac enhanced hy addition of yeast cxtracl. cell free cxtr:~ct. anti rnixctl culture of PI)B.

• Bulletin of Food Technology
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• v.15 no.2
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• pp.107-111
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• 2002

초고압 가공처리는 별동의 화학 보존제를 사용하지 않고도 저온에서 식품유래 미생물을 사멸시킬 수 있기 때문에 식품분야에서 주목받는 새로운 가공기술이다. 이러한 초고압 처리의 장점 덕분에 관능적 특성이 우수하고 영양성분이 그대로 보존되는 고품질 식품의 제조도 가능하다. 고압 조건에서의 미생물 사멸정도를 측정하기 위해서는 흔히 실험실 규모의 장비(그림 1)을 사용하여 소량의 미생물 접종액을 처리함으로서 대량 처리시(그림 2)의 양상을 예측할 수 있다. 초기에 개발된 실험실 귬의 초고압 처리장비에는 일반적으로 고압용기 내부에 온도감지 장치가 부착되어 있지 않아, 압력 조건 하에서의 압축발열 및 순간 감압냉각 효과가 제대로 보고되지 않았다. 그러나 가열효과를 고려하지 않으면 초고압 처리기 특유의 가압 특성 대문에 실험 결과의 재현성을 얻기가 힘들고, 특히 대용량 생산설비의 경우 더욱 그러하다. 이론적으로 초고압 처리는 매우 예측 가능한 공정이다. 즉 고압요기 내부에서는 어느 지점이던 간에 압력이 고르게 분포되고, 가열 확산에 근거한 처리공정과는 달리 압력이 모든 지점에 순간적으로 공정상 불균일이 야기될 소지가 있는 부분은 오직 압축에 다른 발열과 열 전달에 의한 온도 편차에 기인한다. 실제로 처리 대상 제품과 압력 전달매체의 압축시 발열정도 차이와 시료, 매체, 고압용기 간의 열 손실 또는 열 흡수 대문에 고압처리 공정에서 온도가 일정하지 않을 수 있다.

• Journal of Food Hygiene and Safety
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• v.19 no.1
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• pp.19-24
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• 2004

Dose-response models in microbial risk assessment can be divided into biologically plausible models and empirical models. Biologically plausible models are formed by the assumptions in dose distribution of microbes, host sensitivity to microbes, and minimal infectious dose of microbes : there are Exponential model and $\beta$-Poisson model, representatively. Empirical models are mainly used to express the toxicity of chemicals : there are Weibull-Gamma model etc. Deviance function (Y) is used to fit available data to dose-response models, and some dose-response models for food-borne pathogens are developed in humans and experimental animals.