• Journal of Microbiology
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• 제34권4호
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• pp.300-304
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• 1996

To define the effects of zooplankton and phytoplankton to bacteria, bacterial numbers, frequency of dividing cells (FDC) and size distribution were performed with image analysis in the surface layer of Lake Soyang. In August 1992, when Anabaena was blooming, the bacterial number increased at daytime. Bacterial numbers and FDC value had a negative correlation (r = 0.83, P < 0.01). Bacterial size spectrums were dynamically changed during the day and night, especially the small bacteria less than $0.5\;{\mu}m^3$. Meanwhile, in October, after the bloom, the bacterial number was only one third of that in August, even though the FDC was higher than that in August. The bacterial numbers of small size class dropped at 13:00. But the size spectrums were relatively constant during the night time. These results suggest that the bacterial growth was tightly coupled with phytoplankton during Anabaena bloom. And after the bloom, the bacterial number was controlled grazing activity of zooplankton at daytime.

• Journal of Microbiology and Biotechnology
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• 제30권2호
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• pp.259-270
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• 2020

Listeria monocytogenes is a gram-positive, facultative anaerobe food pathogen responsible for the listeriosis that mostly occurs during the low-temperature storage of a cold cut or dairy products. To understand the systemic response to a wide range of growth temperatures, L. monocytogenes were cultivated at a different temperature from 10℃ to 42℃, then whole cell proteomic analysis has been performed both exponential and stationary cells. The specific growth rate increased proportionally with the increase in growth temperature. The maximum growth rate was observed at 37℃ and was maintained at 42℃. Global protein expression profiles mainly depended on the growth temperatures showing similar clusters between exponential and stationary phases. Expressed proteins were categorized by their belonging metabolic systems and then, evaluated the change of expression level in regard to the growth temperature and stages. DnaK, GroEL, GroES, GrpE, and CspB, which were the heat&cold shock response proteins, increased their expression with increasing the growth temperatures. In particular, GroES and CspB were expressed more than 100-fold than at low temperatures during the exponential phase. Meanwhile, CspL, another cold shock protein, overexpressed at a low temperature then exponentially decreased its expression to 65-folds. Chemotaxis protein CheV and flagella proteins were highly expressed at low temperatures and stationary phases. Housekeeping proteins maintained their expression levels constant regardless of growth temperature or growth phases. Most of the growth related proteins, which include central carbon catabolic enzymes, were highly expressed at 30℃ then decreased sharply at high growth temperatures.

• Toxicological Research
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• 제20권1호
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• pp.43-47
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• 2004

In order to investigate the safety of a water extract (ADP) of 1 : 1 mixture of Anemarrhena rhizoma and Phellodendron cortex for alleviating benign prostate hyperplasia, genotoxicity studies in bacterial and mammalian cell assay systems, namely, the Ames bacterial reverse mutation and chromosomal aberration assays were performed. As shown by the results of the Ames bacterial reversion assay, ADP in the range of 625-5000 $\mu\textrm{g}$/plate did not induce mutagenicity in Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537 strains in the absence or in the presence of S9 (the microsomal fraction of rat liver homogenate) metabolic activation. The $IC_{50}$ (50% cell growth inhibition concentration) values of ADP for the chromosomal aberration assay were determined; these were 2425 $\mu\textrm{g}$/ml in the absence and 8126 $\mu\textrm{g}$/ml in the presence of S9 metabolic activation in Chinese hamster lung (CHL) fibroblast cell culture. No chromosomal aberration was observed in CHL cells treated with ADP at 2425, 1212.5 and 606.25 $\mu\textrm{g}$/ml in the absence, or at 8126, 4063 and 2031.5 $\mu\textrm{g}$/ml in the presence of S9 metabolic activation. These results show that under the conditions used, ADP does not harmfully affect the bacterial or mammalian cell system at the gene level.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1467-1475
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• 2015

The use of microbial extracts containing plant hormones is a promising technique to improve crop growth. Little is known about the effect of bacterial cell-free extracts on plant growth promotion. This study, based on phytohormonal analyses, aimed at exploring the potential mechanisms by which Enterococcus faecium LKE12 enhances plant growth in oriental melon. A bacterial strain, LKE12, was isolated from soil, and further identified as E. faecium by 16S rDNA sequencing and phylogenetic analysis. The plant growth-promoting ability of an LKE12 bacterial culture was tested in a gibberellin (GA)-deficient rice dwarf mutant (waito-C) and a normal GA biosynthesis rice cultivar (Hwayongbyeo). E. faecium LKE12 significantly improved the length and biomass of rice shoots in both normal and dwarf cultivars through the secretion of an array of gibberellins (GA₁, GA₃, GA₇, GA₈, GA₉, GA₁₂, GA₁₉, GA₂₀, GA₂₄, and GA₅₃), as well as indole-3-acetic acid (IAA). To the best of our knowledge, this is the first study indicating that E. faecium can produce GAs. Increases in shoot and root lengths, plant fresh weight, and chlorophyll content promoted by E. faecium LKE12 and its cell-free extract inoculated in oriental melon plants revealed a favorable interaction of E. faecium LKE12 with plants. Higher plant growth rates and nutrient contents of magnesium, calcium, sodium, iron, manganese, silicon, zinc, and nitrogen were found in cell-free extract-treated plants than in control plants. The results of the current study suggest that E. faecium LKE12 promotes plant growth by producing GAs and IAA; interestingly, the exogenous application of its cell-free culture extract can be a potential strategy to accelerate plant growth.

• 한국동물생명공학회지
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• 제37권3호
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• pp.169-175
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• 2022

Bovine mammary epithelial (MAC-T) cells are commonly used to study mammary gland development and mastitis. Lipopolysaccharide is a major bacterial cell membrane component that can induce inflammation. Autophagy is an important regulatory mechanism participating in the elimination of invading pathogens. In this study, we evaluated the mechanism underlying bacterial mastitis and mammary cell death following lipopolysaccharide treatment. After 24 h of 50 ㎍/mL lipopolysaccharide treatment, a significant decrease in the proliferation rate of MAC-T cells was observed. However, no changes were observed upon treatment of MAC-T cells with 10 ㎍/mL of lipopolysaccharide for up to 48 h. Thus, upon lipopolysaccharide treatment, MAC-T cells exhibit dose-dependent effects of growth inhibition at 10 ㎍/mL and death at 50 ㎍/mL. Treatment of MAC-T cells with 50 ㎍/mL lipopolysaccharide also induced the expression of autophagy-related genes ATG3, ATG5, ATG10, ATG12, MAP1LC3B, GABARAP-L2, and BECN1. The autophagy-related LC3A/B protein was also expressed in a dose-dependent manner upon lipopolysaccharide treatment. Based on these results, we suggest that a high dose of bacterial infection induces mammary epithelial cell death related to autophagy signals.

• Journal of Ginseng Research
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• 제40권4호
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• pp.453-461
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• 2016

Background: This study aims to describe the characterization of Paenibacillus polymyxa GBR-1 (GBR-1) with respect to its positive and negative effects on plants. Methods: The morphological characteristics of GBR-1 were identified with microscopy, and subjected to Biolog analysis for identification. Bacterial population and media optimization were determined by a growth curve. The potential for GBR-1 as a growth promoting agent, to have antagonistic activity, and to have hydrolytic activity at different temperatures was assessed. The coinoculation of GBR-1 with other microorganisms and its pathogenicity on various stored plants, including ginseng, were assessed. Results: Colony morphology, endospore-bearing cells, and cell division of GBR-1 were identified by microscopy; identification was performed by utilizing the Biolog system, gas chromatography of fatty acid methyl esters (GC-FAME). GBR-1 showed the strongest antagonistic activity against fungal and bacterial pathogens. GBR-1 cell numbers were relatively higher when the cells were cultured in brain heart infusion (BHI) medium when compared with other media. Furthermore, the starch-hydrolytic activity was influenced by GBR-1 at higher temperature compared to low temperatures. GBR-1 was pathogenic to some of the storage plants. Coinoculation of GBR-1 with other pathogens causes differences in rotting on ginseng roots. A significant growth promotion was observed in tobacco seedlings treated with GBR-1 suspensions under in vitro conditions, suggesting that its volatile organic compounds (VOCs) might play a role in growth promotion. Conclusion: The results of this study indicate that GBR-1 has both positive and negative effects on ginseng root and other stored plants as a potential biocontrol agent and eliciting in vitro growth promotion.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.754-757
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• 2001

Expression of the vhb gene encoding bacterial hemoglobin (VHb) from Vitreoscilla has been used to improve recombinant cell growth and enhance product formation under microaerobic conditions because of its ability to enhance oxygen use. We coexpressed GFP and VHb in Escherichia coli BL21 and W3110, and compared with GFP control which was not expressed VHb. We used nar oxygen-dependent inducible promoter for VHb expression. The GFP amounts in E. coli expressed VHb was about five fold higher than in the control Fluorescence intensity was increased about two fold.

• Journal of Microbiology and Biotechnology
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• 제21권3호
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• pp.243-251
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• 2011

The gene bolA was discovered in the 80's, but unraveling its function in the cell has proven to be a complex task. The BolA protein has pleiotropic effects over cell physiology, altering growth and morphology, inducing biofilm formation, and regulating the balance of several membrane proteins. Recently, BolA was shown to be a transcription factor by repressing the expression of the mreB gene. The present report shows that BolA is a transcriptional regulator of the dacA and dacC genes, thus regulating both DD-carboxypeptidases PBP5 and PBP6 and thereby demonstrating the versatility of BolA as a cellular regulator. In this work, we also demonstrate that reduction of cell growth and survival can be connected to the overexpression of the bolA gene in different E. coli backgrounds, particularly in the exponential growth phase. The most interesting finding is that overproduction of BolA affects bacterial growth differently depending on whether the cells were inoculated directly from a plate culture or from an overnight batch culture. This strengthens the idea that BolA can be engaged in the coordination of genes that adapt the cell physiology in order to enhance cell adaptation and survival under stress conditions.

• Journal of Microbiology
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• 제35권4호
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• pp.284-289
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• 1997

A Gram (-), rod-shaped bacterium $2.3{\sim}2.8{\times}0.45{\mu}m$ in size which exhibited growth-inhibiting effects against a cyanobacterium (Anabaena cylindrica) was isolated from Daechung Dam Reservoir. This isolate was identified as Moraxella sp. and designated Moracella sp. CK-1. Hollow zones formed around bacterial colonies on the cyanobacterial lawn. In a mixed-culture of A. cylindrica and the isolate, each microorganism grew inverse-proportionally, and the cyanobacterial vegetative cells completely disappeared within 24 hours. On treatment with Moraxella sp. CK-1, cell walls of A. cylindrica disappeared, but sheathes remained in a more electron dense form. The unit membrane such as thylakoidal membrane was stable to bacterial lysing activity. This bacterium showed a broad action spectrum against cyanobacteria. The growth-inhibiting activity of Moracella sp. CK-1 against A. cylindrica is believed to be performed through the excretion of active substances.

• KSBB Journal
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• 제13권2호
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• pp.119-124
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• 1998

Twelve bacterial strains capable of growing on phenol minimal medium were isolated from iron foundry activated sludge by enrichment culture, and amount them, one isolate which was the best in cell growth and phenol degradation was selected and identified as Acinetobacter junii POH. The optimal temperature, initial pH and phenol concentration in the above medium were 3$0^{\circ}C$, 7.5 and 1000 ppm, respectively. Cell growth of Acinetobacter junii POH dramatically increased 20 hrs cultivation-time and reached a almost stationary phsae 40 hrs cultivation-time then phenol was degraded about 98%. Cell growth was inhibited y phenol at concentrations over 1500 ppm. The isolate was resistant to several antibiotics as well as various heavy metal ions. The growth-limiting log P value of Acinetobacter junii POH on organic solvents was 2.9 in the LB medium. Therefore, it is suggested that Acinetobacter junii POH could be effectively used for the biological treatment of wastewater containing the presence of heavy metal ions and organic solvents.