• Applied Biological Chemistry
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• 제41권1호
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• pp.53-59
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• 1998

수종의 두과작물과 수도에서 분리한 Rhizobium 및 Azospirillum들의 내염성을 조사하고 salt stress에 의하여 유도되는 균주의 생리적 특성 및 식물이나 미생물에서 osmoprotectant 로 작용하는 proline, glycine betaine 및 glutamate가 질소고정균의 생육이나 질소고정력에 미치는 영향을 연구하였다. 분리된 대부분의 질소고정균들은 0.6 M NaCl 농도에서 생육이 현저히 감소되었지만 Acacia rhizobia sp86 은 1.4 M NaCl 농도에서도 생육이 가능하였다. Osmotic stress에 의하여 증가되는 intracellular 유리아미노산은 Rhizobium 및 Azospirillum에서 glutamate 였으며, 특히 Acacia rhizobia sp86은 salt stress에 의하여 5배정도 glutamate를 축적하였다. Osmoprotectant (proline, glycine betaine, glutamate)를 배지내에 1 mM 첨가함으로서 salt stress에 의하여 감소되는 질소고정균의 생육과 질소고정력을 방지하였으며, glycine betaine이 가장 효과적이었다.

• Journal of Microbiology and Biotechnology
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• 제23권11호
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• pp.1560-1568
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• 2013

Salmonella, a main cause of foodborne diseases, encounters a variety of environmental stresses and overcomes the stresses by multiple resistance strategies. One of the general responses to hyperosmotic stress is to import or produce compatible solutes so that cells maintain fluid balance and protect proteins and lipids from denaturation. The ProP and ProU systems are the main transport systems for compatible solutes. The OsmU system, recently identified as a third osmoprotectant transport system, debilitates excessive growth as well by reducing production of trehalose. We studied a fourth putative osmoprotectant transport system, YehZYXW, with high sequence similarity with the OsmU system. A Salmonella strain lacking YehZ, a predicted substrate-binding protein, did not suffer from hyperosmolarity but rather grew more rapidly than the wild type regardless of glycine betaine, an osmoprotectant, suggesting that the YehZYXW system controls bacterial growth irrespective of transporting glycine betaine. However, the growth advantage of ${\Delta}yehZ$ was not attributable to an increase in OtsBA-mediated trehalose production, which is responsible for the outcompetition of the ${\Delta}osmU$ strain. Overexpressed YehZ in trans was capable of deaccelerating bacterial growth vice versa, supporting a role of YehZ in dampening growth. The expression of yehZ was increased in response to nutrient starvation, acidic pH, and the presence of glycine betaine under hyperosmotic stress. Identifying substrates for YehZ will help decipher the role of the YehZYXW system in regulating bacterial growth in response to environmental cues.

• Journal of Plant Biotechnology
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• 제5권3호
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• pp.157-161
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• 2003

Proline is known as an osmoprotectant accumulating in response to salt and dehydration stresses. An increased level of proline is achieved by either an induced synthesis or a reduced degradation of proline. In an attempt to increase salt tolerance in carrot, a P5CS gene from mothbean was introduced via an Agrobacterium-mediated transformation. The resulting carrot cells and the regenerated plants containing the transgene showed increased levels of proline compared to nontransgenics. The transgenic cell line, Pj2 showed about 6 times increased degree of tolerance determined by relative growth after a treatment in 250 mM NaCl. In facts, due to the retarded growth shown in non-saline condition, Pj2 cells grow only about 1.2 times better than nontransgenic control under salt stress condition. Taken together, it appears that a P5CS is a key enzyme in proline biosynthesis and the increased accumulation of proline by overexpression of the enzyme is enough to enhance tolerance to salt stress in carrot.

• Journal of Microbiology and Biotechnology
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• 제29권10호
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• pp.1591-1602
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• 2019

To shed light on the genetic basis of salt tolerance in Enterococcus faecium, Enterococcus faecalis, and Tetragenococcus halophilus, we performed comparative genome analysis of 10 E. faecalis, 11 E. faecium, and three T. halophilus strains. Factors involved in salt tolerance that could be used to distinguish the species were identified. Overall, T. halophilus contained a greater number of potassium transport and osmoprotectant synthesis genes compared with the other two species. In particular, our findings suggested that T. halophilus may be the only one among the three species capable of synthesizing glycine betaine from choline, cardiolipin from glycerol and proline from citrate. These molecules are well-known osmoprotectants; thus, we propose that these genes confer the salt tolerance of T. halophilus.

• 한국식품과학회지
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• 제28권3호
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• pp.451-457
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• 1996

Bifidobacterium breve의 최적 배양 조건과 안정성을 증진시킬 수 있는 배양조건을 조사하기 위하여 pH와 L-cysteine HCI의 첨가효과를 조사하였다. 최대 균체수를 얻기위한 pH 조건은 pH $6.0{\sim}6.5$가 최적 배양 조검임을 알 수 있었다. 저장시의 최적 배양 조건은 $5.5{\sim}6.0$에서 가장 우수하였다. pH $5.5{\sim}6.0$에서 배양한 균주를 $4^{\circ}C$에서 저장시 25일 이후에 $2.4{\times}10^6/ml$와 $1.4{\times}10^6/ml$로 $10^6/ml$ 이상을 유지하여 저장시 안정성이 우수한 반면 pH 7.0에서 배양한 균주는 $2.4{\times}10^6/ml$로 저장시 생존력이 상당히 낮았으며 pH 5.5와 6.0에서 배양한 균주의 ${\beta}$-galactosidase 활력은 25일 저장 이후에도 $78{\sim}85%$를 유지한 반면 pH 7.0에서 배양한 균주의 ${\beta}$-galactosidase 활력은 급격히 감소하였다. L-cysteine HCI 첨가 효과는 0.05% 이상 첨가시 증식에 유리한 환경을 제공하였으며 과산화수소에 대한 내성은 $0.05{\sim}0.10%$ L-cysteine HCI을 첨가한 배이에서 증식한 B. breve가 우수하였다. Osmoprotectant를 첨가하여 배양시 증식과 동결건조시 균주의 안정성에 대한 효과를 조사해 본 결과 2mM betaine이나 2mM trehalose를 첨가시 증식에도 효과가 있었으며 osmoprotectant 역할을 함을 알 수 있었다. 또 한 동결건조에서도 betaine이나 trehalose를 첨가하여 배양된 B. breve는 거의 손상을 받지 않음을 알 수 있었다.

• Journal of Microbiology
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• 제42권3호
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• pp.174-180
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• 2004

A halophilic bacterium was isolated from fermented seafood. The 16S rDNA sequence identity between the isolate and Halomonas subglaciescola AJ306801 was above 95％. The isolate that did not grow in the condition without NaCl or in the condition with other sodium (Na$\^$+/) or chloride ions (Cl$\^$-/) instead of NaCl was named H. subglaciescola DH-l. Two mutants capable of growing without NaCl were obtained by random mutagenesis, of which their total soluble protein profiles were compared with those of the wild type by two-dimensional electrophoresis. The external compatible solutes (betaine and choline) and cell extract of the wild type did not function as osmoprotectants, and these parameters within the mutants did not enhance their growth in the saline environment. In the proton translocation test, rapid acidification of the reactant was not detected for the wild type, but it was detected for the mutant in the condition without NaCl. From these results, we derived the hypothesis that NaCl may be absolutely required for the energy metabolism of H. subglaciescola DH-l but not for its osmoregulation, and the mutants may have another modified proton translocation system that is independent of NaCl, except for those mutants with an NaCl-dependent system.

• Plant Biotechnology Reports
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• 제4권1호
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• pp.75-83
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• 2010

Glycine betaine has been reported as an osmoprotectant compound conferring tolerance to salinity and osmotic stresses in plants. We previously found that the expression of betaine aldehyde dehydrogenase 1 gene (OsBADH1), encoding a key enzyme for glycine betaine biosynthesis pathway, showed close correlation with salt tolerance of rice. In this study, the expression of the OsBADH1 gene in transgenic tobacco was investigated in response to salt stress using a transgenic approach. Transgenic tobacco plants expressing the OsBADH1 gene were generated under the control of a promoter from the maize ubiquitin gene. Three homozygous lines of $T_2$ progenies with single transgene insert were chosen for gene expression analysis. RT-PCR and western blot analysis results indicated that the OsBADH1 gene was effectively expressed in transgenic tobacco leading to the accumulation of glycine betaine. Transgenic lines demonstrated normal seed germination and morphology, and normal growth rates of seedlings under salt stress conditions. These results suggest that the OsBADH1 gene could be an excellent candidate for producing plants with osmotic stress tolerance.

• Journal of Microbiology and Biotechnology
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• 제34권7호
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• pp.1443-1451
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• 2024

Weizmannia coagulans can be used as a starter strain in fermented foods or as a probiotic. However, it is salt-sensitive. Here, W. coagulans genomes were compared with the genomes of strains of Bacillus species (B. licheniformis, B. siamensis, B. subtilis, and B. velezensis) that were isolated from fermented foods and show salt tolerance, to identify the basis for the salt-sensitivity of W. coagulans. Osmoprotectant uptake (Opu) systems transport compatible solutes into cells to help them tolerate osmotic stress. B. siamensis, B. subtilis, and B. velezensis each possess five Opu systems (OpuA, OpuB, OpuC, OpuD, and OpuE); B. licheniformis has all except OpuB. However, W. coagulans only has the OpuC system. Based on these findings, the opuA and opuB operons, and the opuD and opuE genes, were amplified from B. velezensis. Expression of each of these systems, respectively, in W. coagulans increased salt-tolerance. W. coagulans expressing B. velezensis opuA, opuD, or opuE grew in 10.5% NaCl (w/v), whereas wild-type W. coagulans could not grow in 3.5% NaCl. The salt resistance of B. subtilis was also increased by overexpression of B. velezensis opuA, opuB, opuD, or opuE. These results indicate that the salt-susceptibility of W. coagulans arises because it is deficient in Opu systems.

• Molecules and Cells
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• 제39권6호
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• pp.477-483
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• 2016

Heat shock factors (Hsfs) are central regulators of abiotic stress responses, especially heat stress responses, in plants. In the current study, we characterized the activity of the Hsf gene HsfA3 in Arabidopsis under oxidative stress conditions. HsfA3 transcription in seedlings was induced by reactive oxygen species (ROS), exogenous hydrogen peroxide ($H_2O_2$), and an endogenous $H_2O_2$ propagator, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB). HsfA3-overexpressing transgenic plants exhibited increased oxidative stress tolerance compared to untransformed wild-type plants (WT), as revealed by changes in fresh weight, chlorophyll fluorescence, and ion leakage under light conditions. The expression of several genes encoding galactinol synthase (GolS), a key enzyme in the biosynthesis of raffinose family oligosaccharides (RFOs), which function as antioxidants in plant cells, was induced in HsfA3 overexpressors. In addition, galactinol levels were higher in HsfA3 overexpressors than in WT under unstressed conditions. In transient transactivation assays using Arabidopsis leaf protoplasts, HsfA3 activated the transcription of a reporter gene driven by the GolS1 or GolS2 promoter. Electrophoretic mobility shift assays showed that GolS1 and GolS2 are directly regulated by HsfA3. Taken together, these findings provide evidence that GolS1 and GolS2 are directly regulated by HsfA3 and that GolS enzymes play an important role in improving oxidative stress tolerance by increasing galactinol biosynthesis in Arabidopsis.

• Journal of Plant Biotechnology
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• 제45권4호
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• pp.357-363
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• 2018

The objective of this study was to investigate whether exogenous proline (Pro) could confer freezing tolerance of spinach and determine fluctuations of free amino acids in spinach leaf tissues under freeze-induced stress. Treatment with Pro (10 mM) resulted in more accumulation of Pro (~2.6-fold) in Pro-treated spinaches compared to untreated ones. These Pro-pretreated spinaches were more freezing-tolerant, showing more turgid leaves and petioles compared to untreated controls. However, when spinaches pre-treated with or without Pro were subjected to freezing, there was no significant difference in overall amino acid contents, emphasizing the role of Pro as an osmoprotectant. Freezing stress prompted intensification of total amino acid contents irrespective of pretreatment with Pro. Asp, Glu, Ala, and Val were the most abundant free amino acids due to increased protein degradation and nitrogen mobilization for plant survival under freezing stress. Arg, a precursor for the synthesis of polyamines in plants, was profoundly enhanced under freezing stress. This implies that Arg plays an important role in modulating freezing tolerance. Gly, Leu, and Ile were maintained at relatively low levels in all treatments. However, Ser, Tyr, and Lys as primary constituents of dehydrins were accumulated under freezing stress, suggesting that they might play a role in increasing cryoprotective activity under freezing stress.