• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.118-124
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• 2005

In this research, we examined the effect of NaCl on the growth, energy metabolism, and proton motive force of Halomonas salina, and the effect of compatible solutes on the bacterium growing in the high salinity environment. H. salina was isolated from seawater and identified by 16srDNA sequencing. The growth of H. salina was not enhanced by the addition of external compatible solutes (choline and betaine) in the high salinity environment. The resting cells of H. salina absorbed more glucose in the presence of 2.0 M NaCl than in its absence. H. salina did not grow in the medium with either KCl, RbCl, CsCl, $Na_2SO_4$, or $NaNO_3$, in place of NaCl. The optimal concentration of NaCl for the growth of H. salina ranged from 1.4 M to 2.5 M, and the growth yield was decreased in the presence of NaCl below 1.4M and above 2.5M. The activity of isocitrate dehydrogenase, pyruvate dehydrogenase, and malate dehydrogenase of H. salina was not inhibited by NaCl in in vitro test. The proton translocation of H. salina was detected in the presence of NaCl only. These results indicate that NaCl is absolutely required for the normal growth and energy metabolism of H. salina, but the bacterial growth is not enhanced by the compatible solutes added to the growth medium.

• 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 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.

• Molecules and Cells
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• 제24권1호
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• pp.45-59
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• 2007

We describe the gene expression profile of third leaves of rice (cv. Nipponbare) seedlings subjected to salt stress (130 mM NaCl). Transcripts of Mn-SOD, Cu/Zn-SOD, cytosolic and stromal APX, GR and CatB were up-regulated, whereas expression of thylakoid-bound APX and CatA were down-regulated. The levels of the compatible solute proline and of transcripts of its biosynthetic gene, ${\Delta}^1$-pyrroline-5-carboxylate synthetase (P5CS), were strongly increased by salt stress. Interestingly, a potential compatible solute, ${\gamma}$-aminobutyric acid (GABA), was also found to be strongly induced by salt stress along with marked up-regulation of transcripts of GABA-transaminase. A dye-swap rice DNA microarray analysis identified a large number of genes whose expression in third leaves was altered by salt stress. Among 149 genes whose expression was altered at all the times assayed (3, 4 and 6 days) during salt stress, there were 47 annotated novel genes and 76 unknown genes. These results provide new insight into the effect of salt stress on the expression of genes related to antioxidant enzymes, proline and GABA as well as of genes in several functional categories.

• 동아시아식생활학회지
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• 제5권2호
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• pp.19-26
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• 1995

Staphylococcus aureus, the most salt-tolerant nonhalophilic bacterium, is the only foodborne pathogen that is able to grow at a levels below 0.90. The fundamental osmorgulatory strategy used by this organism involves the accumulation of intracellular compatible solutes such as proline or glycine betaine which are accumulated by transport and act as osmoregulators in cells. In this study, levels of proline transport systems and glycine betaine transport system of S. aureus were examined when cells are grown at high osmolarity. The levels of all three transport systems within S. aureus were elevated at high osmolarity and the most dramatic increase was found for the low-affinity proline transport system. However, in 5mM glycine betaine-supplemented medium, the level of the low-affinity proline transport system did not become elevated when cultures were grown at high osmolarity. The metabolic fate of the accumulated proline and glycine getaine was investigated by thin-layer chromatography an found to be not metabolized by S. aureus.

• The Korean Journal of Ecology
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• 제27권6호
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• pp.355-361
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• 2004

염습지와 사구지역에 생육하는 해안식물의 생리생태학적 특성을 이해하기 위하여 무기이온($Ca^{2+},\;Na^+,\;K^+,\;Mg^{2+},\;Cl^-$)과 유기용질(수용성 당, glycine betaine)을 정량적으로 측정하였다. 명아주과 식물(가는갯능쟁이, 퉁퉁마디, 솔장다리, 나문재, 칠면초)은 $K^+$이온 대신에 $Na^+$이온과 $Cl^-$이온을 축적하는 경향을 보였다. 그러나 교란지에 서식하는 좀명아주는 다른 명아주과 식물에 비해 $Na^+$이온 대신에 높은 $K^+$이온을 함유하였다. 조사된 대부분의 명아주과 식물은 체내 수용성 $Ca^{+2}$이온의 함량이 낮고, 비교적 소량의 수용성 당을 함유하였으며, glycine betaine을 다량 함유하였다. 이와는 대조적으로 단자엽에 속하는 벼과(갯쇠보리, 갈대, 갯잔디)와 사초과(통보리사초, 좀보리사초)의 식물은 $Na^+$와 $Cl^-$이온을 효과적으로 배제하여 체내 낮은 함량을 유지하였으며, 또한 $K^+$이온을 선호하며, 명아주과 식물보다 더 많은 당을 삼투물질로 축적하였다. 결론적으로, 명아주과식물은 무기이온과 glycine betaine을 축적하고, 단자엽식물은 $K^+$이온과 수용성 당을 축적하는 효과적인 이온조절을 통해 염습지 및 사구지역에 적응하는 것으로 여겨진다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.21-25
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• 1999

Two low-salt complex media, bactopeptone and desalted yeast extract, were used for high density cultivation of the hyperthermophilic archaeon Sulfolobus solfataricus (DSM 1617). Bactopeptone, which has low mineral ion content among various complex media, was good for cell growth in batch cultures; the maximal cell density in bactopeptone was comparable to that in yeast extract. However, cell growth was rather poor when bactopeptone was added by the fed-batch procedure. Since several vitamins are deficient in abctopeptone, the effect of vitamins on cell growth was examined. Among the vitamins tested, pyridoxine was found to improve the growth rate of S. solfataricus. To reduce the growth inhibition caused by mineral ions, yeast extract was dialyzed against distilled water and then fed-batch cultures were carried out using a fed medium containing desalted yeast extract. Although the concentrations of mineral ions in yeast extract were significantly lowered by the dialysis whether low molecular weight solutes in yest extract are crucial for cell growth, we investigated the effect of trehalose, a most abundant compatible solute in yeast extract, on the growth pattern. Cell densities were increased and the length of the lag phase was markedly shortened by the presence of trehalose, indicating that trehalose plays an important role in the growth of S. solfataricus.

• Plant Biotechnology Reports
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• 제5권1호
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• pp.89-103
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• 2011

Two rice varieties, viz. Nonabokra and Pokkali, have been evaluated for their responses to salinity in terms of some physiological and biochemical attributes. During the exposure to salinity (200 mM concentration of sodium chloride for 24, 48, and 72 h), a significant increase in sodium was recorded which was also concomitant with the changes of other metabolic profiles like proline, phenol, polyamine, etc. The protein oxidation was significantly increased and also varied between the two cultivars. The changes in activities of anti-oxidative enzymes under stress were significantly different to the control. The detrimental effects of salinity were also evident in terms of lipid peroxidation, chlorophyll content, protein profiles, and generation of free radicals; and these were more pronounced in Pokkali than in Nonabokra. The assessment and analysis of these physiological characters under salinity could unravel the mechanism of salt responses revealed in this present study and thus might be useful for selection of tolerant plant types under the above conditions of salinity.

• 미생물학회지
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• 제54권3호
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• pp.280-282
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• 2018

Gammaproteobacteria에 속하는 Pseudoalteromonas sp. meg-B1을 제주도 해양 퇴적물로부터 분리하였다. 본 연구에서는 대략 4.15 Mb의 크기와 41.2%의 평균 G + C 함량을 가진 meg-B1 균주의 완전한 유전체를 보고한다. 유전체는 3,606개의 코딩 서열, 9개의 리보솜 RNA 및 94개의 전사 RNA 유전자가 존재하며, 한 개의 완전한 프로파지 영역이 발견되었다. 본 유전체는 해양환경에서 생존하기 위한 삼투화합성 용질합성과 관련된 유전자(예, choline dehydrogenase)들이 확인되었다.

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.1-10
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• 2019

Saline soils comprise more than half a billion hectares worldwide. Thus, they warrant attention for their efficient, economical, and environmentally acceptable management. Halophytes are being progressively utilized for human benefits. The halophyte microbiome contributes significantly to plant performance and can provide information regarding complex ecological processes involved in the osmoregulation of halophytes. Microbial communities associated with the rhizosphere, phyllosphere, and endosphere of halophytes play an important role in plant health and productivity. Members of the plant microbiome belonging to domains Archaea, Bacteria, and kingdom Fungi are involved in the osmoregulation of halophytes. Halophilic microorganisms principally use compatible solutes, such as glycine, betaine, proline, trehalose, ectoine, and glutamic acid, to survive under salinity stress conditions. Plant growth-promoting rhizobacteria (PGPR) enhance plant growth and help to elucidate tolerance to salinity. Detailed studies of the metabolic pathways of plants have shown that plant growth-promoting rhizobacteria contribute to plant tolerance by affecting the signaling network of plants. Phytohormones (indole-3-acetic acid and cytokinin), 1-aminocyclopropane-1-carboxylic acid deaminase biosynthesis, exopolysaccharides, halocins, and volatile organic compounds function as signaling molecules for plants to elicit salinity stress. This review focuses on the functions of plant microbiome and on understanding how the microorganisms affect halophyte health and growth.