• Microbiology and Biotechnology Letters
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• v.52 no.1
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• pp.1-14
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• 2024

This study focused on isolating and identifying strains from the gut of Epinephelus akaara cultivated in aquaculture facilities on Jeju Island. The aim was to evaluate the potential of utilizing these strains as probiotics for industrial applications. A total of 129 strains were isolated from the gut of E. akaara and screened based on their ability to create a clear zone of 10 mm or more in a preliminary antimicrobial activity test. Twelve strains were selected for further analysis, including bile resistance, acid tolerance at different pH levels, antioxidant activity, antibiotic susceptibility, and biochemical characteristics using the API kit. Through these characteristic experiments, eight strains (G1, G3, G15, G21, B1, B2, B3, B5) were identified as having potential as probiotics. Among these, the B group strains (B1, B2, B3, B5) exhibited significantly higher activity compared to the G group strains (G1, G3, G15, G21). Based on the phylogenetic analysis of the 16S rRNA gene sequences of the selected microorganisms, the strains were named as follows: B1 strain as Lactobacillus paracasei B1, B2 strain as Lactococcus lactis B2, B3 strain as Lactobacillus plantarum B3, B5 strain as Lactococcus lactis subsp. hordniae B5, G1 strain as Bacillus licheniformis G1, G3 strain as Bacillus velezensis G3, G15 strain as Brevibacterium frigoritolerans G15, and G21 strain as Bacillus pumilus G21.

• Journal of Mushroom
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• v.15 no.1
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• pp.8-13
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• 2017

An auxin-producing bacterial strain, designated 4-3, was isolated from waste button mushroom compost in Boryeong-si, Chungnam. The strain 4-3 was classified as a novel strain of Leucobacter tardus, based on chemotaxonomic and phylogenetic analyses. TLC and HPLC the isolated L. tardus strain 4-3 produced indole-3-acetic acid (IAA), the auxin. Maximum IAA productionof $94.3mg\;L^{-1}$ was detected for bacteria cultured in R2A medium with 0.1% l-tryptophan, incubated for 24 h at $35^{\circ}C$. Negative correlationwas observed between IAA production and pH of the culture medium, indicating that the increase inIAA caused acidification ofthe medium. The effect of supplementation with varying concentrations of l-tryptophan, a known precursor of IAA, was also assessed. production was maximal at 0.1% l, but decreased at lconcentrations above 0.2%. To investigate the plant growth-promoting effects of the bacterium, L. tardus strain 4-3 culture broth was used to inoculate water cultures and seed pots of mung bean. We found thatadventitious root induction and root growth were 2.2-times higher in thethan in the non-inoculated plants.

• Journal of Plant Biotechnology
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• v.47 no.2
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• pp.118-123
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• 2020

The black seed coat of soybeans contain anthocyanins which promote health. However, mature soybean seeds contain anti-nutritional factors like lipoxygenase, lectin and Kunitz Trypsin Inhibitor (KTI) proteins. Furthermore, these seeds can be used only after the genetic elimination of these proteins. Therefore, the objective of this study was to develop novel soybean genotypes with black seed coat and triple recessive alleles (lx1lx1lx2lx2lx3lx3, titilele) for lipoxygenase, lectin, and KTI proteins. From a cross of parent1 (lx1lx2lx3/lx1lx2lx3, ti/ti, Le/Le) and parent2 (lx1lx2lx3/lx1lx2lx3, Ti/Ti, le/le), 132 F₂ seeds were obtained. A 3:1 segregation ratio was observed during F₂ seed generation for the inheritance of lectin and KTI proteins. Between a cross of the Le and Ti genes, the observed independent inheritance ratio in the F₂ seed generation was 9: 3 : 3 : 1 (69 Le_Ti_: 32 leleTi_: 22 Le_titi: 9 leletiti) (χ²=2.87, P=0.5 - 0.1). From nine F₂ seeds with triple recessive alleles (lx1lx1lx2lx2lx3lx3, titilele genotype), one novel strain posessing black seed coat, and free of lipoxygenase, lectin and KTI proteins, was selected. The seed coat color of the new strain was black and the cotyledon color of the mature seed was green. The weight of 100 seeds belonging to the new strain was 35.4 g. This black soybean strain with lx1lx1lx2lx2lx3lx3, titilele genotype is a novel strain free of lipoxygenase, lectin, and KTI proteins.

• YAKHAK HOEJI
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• v.3 no.1
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• pp.15-20
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• 1957

Resume 1. The toxic effect of $CuSO_4$ on the growth of yeast began in the 0.2mM and colony formation was completely inhibited in the 3mM $CuSO_4$ media. 2. The yeast strain which was trained sucessively from lower concentration media to higher one, could grow even in 10mM $CuSO_4$ media. 3. Rlb strain produced brown pigment in copper media. 4. Resistance of Rlb strain to $CuSO_4$ did not revert in non copper media. 5. The appearance of resistant strain was regarded as the result of "Mutation and Selection". 6. The alcohol fermentation ability of Rlb strain was lower than that of parent strain. 7. Rlb strain yielded some effective substance which induced the parent strain to resist against $CuSO_4$. 8. The dehydrogenase activity of yeast was inhibited by $CuSO_4$.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.42-45
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• 2012

The mechanical behavior and microstructural evolution during high temperature tensile deformation of recrystallized Ni3Al polycrystals doped with boron were investigated as functions of initial grain size, tensile strain rate and temperature. In order to obtain more precise information on the deformation mechanism, tensile specimens were rapidly quenched immediately after deformation at a cooling rate of more than $2000Ks^{-1}$, and were then observed by transmission electron microscopy (TEM). Mechanical tests in the range of 923 K to 1012 K were carried out in a vacuum of less than $3{\times}10^{-4}$ Pa using an Instron-type machine with various but constant cross head speeds corresponding to the initial strain rates from $1.0{\times}10^{-4}$ to $3.1{\times}10^{-5}s^{-1}$. After heating to deformation temperature, the specimen was kept for more than 1.8 ks before testing. The following results were obtained: (1) Flow behavior was affected by initial strain size; with decreasing initial grain size, the level of a stress peak in the true stress-true strain curve decreased, the steady state region was enlarged and elongation increased. (2) On the basis of TEM observation of rapidly quenched specimens, it was confirmed that dynamic recrystallization certainly occurred on deformation of fine-grained ($3.3{\mu}m$) and intermediate-grained ($5.0{\mu}m$) specimens at an initial strain rate of $3.1{\times}10^{-5}s^{-1}$ and at 973 K. (3) There were some dislocation-free grains among the new recrystallized grains. The obtained results suggest that both dynamic recrystallization and grain boundary sliding are operative during high temperature deformation.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.177-183
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• 2007

Using complementation of RpoH deficient E. coli strain A7448, the rpoH gene encoding heat shock sigma factor 32 (${\sigma}^{32}$) from Methylovorus sp. strain SS1 DSM11726 was cloned and sequenced. Sequence analysis of a stretch of 1,796-bp revealed existence of an open reading frame encoding a polypeptide of 284 amino acid (32,006 dalton). Deduced amino acid sequence of the Methylovorus sp. strain SS1 RpoH showed that 59.6%, 39.1% and 51.4% identities with those of Nitrosomonas europaea (${\beta}$-proteobacteria), Agrobacterium tumefaciens ($\alpha$-proteobacteria) and E. coli (${\gamma}$-proteobacteria). The expression level of the functional ortholog of RpoH of Methylovorus sp. strain SS1 was increased transiently after heat induction, further indicating that it functions as a heat shock sigma factor.

• ALGAE
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• v.37 no.4
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• pp.317-329
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• 2022

Carotenoids are effective antioxidants that are found in various photosynthetic organisms. Marine microalgae are an advantageous bioresource for carotenoid production because they do not compete with other crops for freshwater and arable land. This study reports a newly isolated Dunaliella strain from the Geumhong Saltpan on Yeongjong Island, West Sea, Korea. The new strain was isolated and classified as Dunaliella salina through phylogenetic analysis and was named the OH214 strain (Deposit ID: KCTC14434BP). The newly isolated strain can survive in a wide range of NaCl concentrations (0.3-5.0 M NaCl), but grows well in 0.6 to 1.5 M NaCl culture medium. Under high-light conditions (500 ± 10 μmol photons m^-2 s^-1), the cells accumulated three times more β-carotene than under low-light conditions (50 ± 5 μmol photons m^-2 s^-1). The cells accumulated 2.5-fold more β-carotene under nitrogen-deficient (1 mM KNO₃) conditions (3.24 ± 0.36 ㎍ 10⁶ cells^-1) than in nitrogen-sufficient conditions (>5 mM KNO₃). The lutein content under nitrogen-deficient conditions (1.73 ± 0.09 ㎍ 10⁶ cells^-1) was more than 24% higher than that under nitrogen-sufficient conditions. Under the optimized culture condition for carotenoid induction using natural seawater, D. salina OH214 strain produced 7.97 ± 0.09 mg g DCW^-1 of β-carotene and 4.65 ± 0.18 mg g DCW^-1 of lutein, respectively. We propose that this new microalga is a promising strain for the simultaneous production of β-carotene and lutein.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.229-235
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• 2011

The formability of magnesium alloy sheets at room temperature is generally low because of the inherently limited number of slip systems, but higher at temperatures over $150^{\circ}C$. Therefore, prior to the practical application of these materials, the forming limits should be evaluated as a function of the temperature and strain rate. This can be achieved experimentally by performing a series of tests or analytically by deriving the corresponding modeling approaches. However, before the formability analysis can be conducted, a model of flow stress, which includes the effects of strain, strain rate and temperature, should be carefully identified. In this paper, such procedure is carried out for Mg alloy AZ31 and the concept of flow stress surface is proposed. Experimental flow stresses at four temperature levels ($150^{\circ}C$, $200^{\circ}C$, $250^{\circ}C$, $300^{\circ}C$) each with the pre-assigned strain rate levels of $0.01s^{-1}$, $0.1s^{-1}$ and $1.0s^{-1}$ are collected in order to establish the relationships between these variables. The temperature-compensated strain rate parameter which combines, in a single variable, the effects of temperature and strain rate, is introduced to capture these relationships in a compact manner. This study shows that the proposed concept of flow stress surface is practically relevant for the evaluation of temperature and strain dependent formability.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.539-549
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• 1995

The purpose of this study was to determine the accuracy of 3 implant impression methods by using strain gauge. The models used for this study were partially edentulous mandibular acrylic resin casts Model A, with two abutment analogs in #46,47 extraction site, represented two implant parallel to to the adjacent natural tooth. Model B represent an anterior implant parallel to the adjacene natural tooth and a posterior implant exhibiting a 15-degree lingual inclination. Master framework were fabricated on the master model, and 3 strain gauges were attached to a master framwork to determine the passivity of fit of the framework to sample casts made by the three impression techniques. The master framework was attached to each sample cast with gold screws, which were tightened with the torque driver to ensure a consistent toque application of 10 Ncm. Universal Digital Measuring System UCAM-5BT was used for strain measuring. Impression techniques studid were : 1. unsplinted tapered impression coping, polyvinyl siloxane, stock tray 2. unsplinted squared impression coping, polyether, custom tray 3. squared impression coping splinted with Duralay resin, polyether, custom tray Through analysis on data from this study, the following conclusions were obtained. 1. There were no statistically significant differences between the mean strain recorded from the sample casts made with the tree impression. But only strain values of model A(parallel group) Y-axis was signifcantly differed between Technique 1 and 3(P<0.05). 2. There was no statistically significant difference between model A(parallel group) and model B(15-degree divergent group).

• Journal of Species Research
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• v.9 no.3
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• pp.204-209
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• 2020

In 2019, as a subset study to discover indigenous yeast species in Korea, a total of 20 yeast species were isolated from soil samples collected in Pochoen-si. Among them, eight strains were unreported species. From the high 26S rRNA gene sequence similarity and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to independent and predefined yeast species. The 20 strains were assigned to the genera Aureobasidium (1 strain) and Meyerozyma (1 strain) of the phylum Ascomycota and Cystofilobasidium (2 strains), Filobasidium (1 strain), Naganishia (2 strains), Bullera (3 strains), Leucosporidium (9 strains) and Sampaiozyma (1 strain) of the phylum Basidiomycota. There is no official report of the following species in Korea: Leucosporidium creatinivorum (4 strains), Leucosporidium escuderoi(2 strains), Leucosporidium golubevii(1 strain) and Leucosporidium intermedium (2 strains). Basic biochemical characteristics, colony and cell morphology are also described in the species description section.