• Korean Journal of Microbiology
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• v.39 no.3
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• pp.135-140
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• 2003

Bacillus sp. secretes high levels of extracellular enzymes into the culture medium. The signal recognition particle (SRP) and the SRP receptor play a central role in targeting pre secretory proteins to the translocase. By the analysis of the DNA microarray of B. lentimorbus WJ5, it was detected that WJ5m12, antifungal activity deficient mutant induced by gamma radiation, had a down-regulated expression of the SRP receptor gene (B. subtitis srb homologue, srbL). To determine the relationship of SRP receptor to antifungal activity, srbL of B. lentimorbus WJ5 was amplified by PCR and ligated into pQE30 vector, and then transferred into WJ5m12. The transformant, WJ5m12::srbL, recovered the antifungal activity. From the 2-DE analysis, the several presecretory proteins accumulated in the mutant cell and decreased to a level of the wild type in WJ5m12::srbL. It seems that the srbL could play an important role in the secretion of the antifungal activity related proteins of B. lentimorbus WJ5.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.15-15
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• 2015

Aspergillus fumigatus is a major cause of invasive aspergillosis (IA), a significant health issue worldwide with high mortality rates up to 95%. Our lab is interested in how A. fumigatus adapts to low oxygen conditions 'hypoxia', which is one of the important host microenvironments. A. fumigatus SrbA is a basic helix-loop-helix (bHLH) transcriptional regulator and belongs to sterol regulatory element binding protein (SREBP) family members. Loss of SrbA completely blocks growth in hypoxia and results in avirulence in murine models of IA suggesting an essential role of SrbA in hypoxia adaptation and virulence in A. fumigatus. We conducted chromatin immunoprecipitation sequencing (ChIP-seq) with A. fumigatus wild type using a SrbA specific antibody, and 97 genes were revealed as SrbA direct targets. One of the 'SrbA regulons' (AFUB_099590) was a putative bHLH transcriptional regulator whose sequence contained a characteristic tyrosine substitution in the basic portion of the bHLH domain of SREBPs. Therefore, we designated AFUB_099590 SrbB. Further characterization of SrbB demonstrated that SrbB is important for radial growth, biomass production, and biosynthesis of heme intermediates in hypoxia and virulence in A. fumigatus. A series of quantitative real time PCR showed that transcription of several SrbA regulons is coordinately regulated by two SREBPs, SrbA and SrbB in hypoxia. This suggests that SrbA and SrbB have both dependent and independent functions in regulation of genes responsible for hypoxia adaptation in A. fumigatus. Together, our data provide new insights into complicated roles of SREBPs in adaptation of host environments and virulence in pathogenic fungi.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.553-559
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• 2007

The vertical distributions of sulfate reducing bacteria (SRB) in sediments of lakes in Korea (Lake Sihwa and Lake Soyang) and China (Lake Aha and Lake Erhai) were investigated by fluorescence in situ hybridization (FISH). SRB from sediment of Lakes of China were located to deeper layer than those in Lakes of Korea. SRB were not detected below 19 cm and 10 cm depth in sediments of Lake Sihwa and Lake Soyang, respectively. SRB numbers were, however, detected at all observed sediments in Lake Aha and Lake Erhai. In case of lakes in Korea, the proportion of SRB ranged from 2.9 to 25.6% (Lake Sihwa) and ranged from 0.6 to 7.1% (Lake Soyang). For lakes in China, the proportions of SRB were from 0.6 to 19.4% and from 2.9 to 11.2% within sediments from Lake Aha and from Lake Erhai, respectively. The high peaks of SRB numbers in sediments of all lakes were appearing at depths between 0 cm and 2 cm.

• Corrosion Science and Technology
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• v.3 no.5
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• pp.187-193
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• 2004

We have investigated the differences between the general corrosion and microbiologically influenced corrosion (MIC) of steels in terms of electrochemical behavior and surface phenomena. Corrosion potential of steels in the absence of SRB (sulfate-reducing bacteria) shifted to a low level and was maintained throughout the experimental period (40 days). The potential in the presence of SRB, however, shifted to a noble level after 20 days' incubation, indicating the growth of SRB biofilms on the test metal specimens and a formation of corrosion products. In addition, the color of medium inoculated with SRB changed from gray to black. The color change appeared to be caused by the formation of pyrites (FeS) as a corrosion product while no significant color change was observed in the medium without SRB inoculation. Moreover, corrosion rates of various steels tested for MIC were higher than those in the absence of SRB. This is probably because SRB were associated with the increasing corrosion rates through increasing cathodic reactions which caused reduction of sulfate to sulfide as well as formation of an oxygen concentration cell. The pitting corrosions were also observed in the SRB-inoculated medium.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.2
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• pp.47-54
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• 1996

UASB reactor was operated for treating wastewater containing high sulfate to assess their performance, competition between sulfate-reducing bacteria(SRB) and methane-producing bacteria(MPB), and the change in the characteristics of microbial granules according to change of hydraulic retention time(HRT) in the reactor. The reactor was fed with a synthetic moderate strength wastes(glucose, 2000 mgCOD/l) containing high sulfate($2400mgSO_4{^{2-}}/l$). The organic loading rate(OLR) ranged from 1.5 to 3.0 gCOD/l.d as HRT maintained 15 to 30 hrs in the stage I. The COD removal efficiency was between 80 to 92%. During this period, methane yield rapidly decreased from 0.3 to 0.1 1 $CH_4$/gCODremoved. While sulfide concentration in the effluent increased from 80 to 200 mgS/l. This indicates that SRB becomes dominant over MPB at a relatively long HRT in the excess sulfate. When OLR of reactor maintained from 5 to 8 gCOD/l.d in the stage II, methane yield increased from 0.1 to 0.17 1 $CH_4$/gCODremoved regardless of decrease of COD removal efficiency. This indicates that SRB is more sensitive to the change of a short HRT than MPB. In the competition between SRB and MPB, about 30% of the removed COD was utilized by SRB at HRT of 30 hrs during the start-up period, while about 73% was used by SRB at HRT of 15hrs at the final step of second experimental stage. Whereas after shock exposure of OLR about 62% was utilized by SRB at HRT of 5hrs. It indicates that SRB is strongly suppressed by the wash-out of significant dispersed SRB since a large electron flow is distributed to the MPB. In addition, the granulation in the presence of high sulfate is unfavoured at a long HRT because of substrate transport limitations into MPB like Methanothrix spp. which is an important factor in the composition of the granules. Accordingly, granule sizes in the UASB reactor decreased with time due to weak network frame of granules by the decreased activity of MPB.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.2
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• pp.120-126
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• 2003

Four different rice varieties, Sindongjinbyeo, Dongjin #1, Saegyehwabyeo, and Iksan 467, were transplanted under three different nitrogen levels and two different seedling numbers per hill to obtain basic information on panicle traits under different cultural conditions and to propose the ideal panicle structure in Japonica rice. Sindongjinbyeo and Iksan 467 were characterized by more primary rachis branches (PRBs) per panicle and more grains on PRB than other cultivars. The two varieties also had fewer secondary rachis branches (SRBs) per PRB and fewer grains on SRB per PRB. These characteristics, consequently, resulted in higher ripened grain rate, contrary to that of Dongjin #1 and Saegyehwabyeo. In the correlation coefficient analysis, PRB number per panicle and grain number on PRB per panicle were positively correlated with ripened grain rate, while SRB number per panicle, number of grains on SRB per panicle, SRB number per PRB, number of grains on SRB per PRB and grain number per panicle were negatively correlated with ripened grain rate. Therefore, the number of grains on PRB per panicle, SRB number per PRB and the number of grains on SRB per PRB were the appropriate criteria for determining and achieving higher ripened grain rate in rice. High ripened grain rate over 90% was obtainable with over 12.5 PRBs per panicle and 63 grains on PRB per panicle, and with under 1.7 SRBs per PRB, 5 grains on SRB per PRB, 130 grains per panicle, and 14 panicles per hill. The study recommended that for over 90% high ripened grain rate, the critical limiting factors should be under 2 SRBs per PRB, 6 grains per PRB, and 130 grains per panicle, irrespective of the PRB number per panicle and the number of grains on PRB.

• Journal of Preventive Medicine and Public Health
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• v.42 no.2
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• pp.143-150
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• 2009

Objectives : South Korea has experienced unprecedented ups and downs in the sex ratio at birth(SRB), which has been a unique phenomenon in the last two decades. However, little is known about socioeconomic factors that influence the SRB. Employing the diffusion theory by Rogers, this study was undertaken to examine the trends in social variations in the SRB from 1981 to 2004 in Korea. Methods : The data was taken from Vital Birth Statistics for the period from 1981-2004. We computed the annual male proportion of live births according to the parental education(university, middle/high school, primary) and occupation(non-manual, manual, others). Logistic regression analysis was employed to estimate the odds ratios of male birth according to social position for the equidistant three time periods(1981-1984, 1991-1994, and 2001-2004). Results : An increased SRB was detected among parents with higher social position before the mid 1980s. Since then, however, a greater SRB was found for the less educated and manual jobholders. The inverse social gradient for the SRB was most prominent in early 1990s, but the gap has narrowed since the late 1990s. The mother's socioeconomic position could be a sensitive indicator of the social variations in the sex ratio at birth. Conclusions : Changes in the relationship of parental social position with the SRB were detected during the 1980-2004 in Korea. This Korean experience may well be explained by diffusion theory, suggesting there have been socioeconomic differences in the adoption and spread of sex-detection technology.

• Journal of Microbiology
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• v.34 no.2
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• pp.131-136
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• 1996

In order to known the extend of contribution to the degradation of organic materials and nutrient recycling by sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB) in sediment, the distribution and activity of these two groups of microorganisms were studied montly in 1994 at two sites, one littoral (Sanggulri) and the other profunndal (DAM), in Lake Soyang. In the seasonal distribution of two microorganisms, SRB were 1.07 $\times$ 10$^{3}$-2.42 $\times$ 10$^{5}$ cells/g-dry weight at Sanggulri, 2.40 $\times$ 10$^{5}$ -1.29 $\times$ 10$^{6}$ at Dam and MPB were 0.52 $\times$ 10$^{3}$ cells/g-dry weight at Sangguri and 1.44 $\times$ 10$^{3}$-6.89 $\times$ 10$^{3}$ at Dam. In these results, the density of SRB in Lake Soyang is much higher than other lakes. These high values might be due to higher sulfate concentration, 0.69-4.05 mM, than normal freshwater, 0.01-1.2 mM. And a good correlation of SRB and chlorophyll a concentration implied that the important environmental factor on distribution of SRB might be the concentration of available organic matter. In a comparison of sulfate-reducing rate and methane producing rate in 1995, the activity of SRB for the degradation of organic matter was higher than MPB by factor of 359. Conclusively SRB superior to MPB in the distribution and activity are more important annearobic bacteria in Lake Soyang sediments.

• Korean Journal of Mathematics
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• v.26 no.2
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• pp.327-335
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• 2018

In this paper, we present the construction of natural invariant measures so called SRB(Sinai-Ruelle-Bowen) measures by the properties of geometric t-potential and Bowen's equation for the hyperbolic attractors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.1
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• pp.240-245
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• 1999

Growth inhibitory effect of doenjang(Korean soypaste) methanol extracts in SRB assay using AGS human gastric adenocarcinoma cell, Hep 3B human hepatocellular carcinoma cell and HT 29 human colon cancer cell was studied. The treatment of doenjang methanol extracts(2mg/assay) to the AGS, Hep 3B and HT 29 cancer cells inhibited the growth of the cancer cells by 55%, 60%, and 71%, respectively. Doenjang methanol extracts exhibited the highest inhibitory effect among other soybean fermented foods and original materials in the SRB assay. In addition, to separate active compounds of doenjang methanol extracts, we fractionated the doenjang with hexane, methanol, dichloromethane, ethylacetate and butanol. Growth inhibitory effect on the AGS, Hep 3B, HT 29 and MG 63 cancer cells was the highest in the fractions of dichloromethane and ethylacetate among other solvent fractions of the doenjang. These results showed that some compounds contained in the fractions of dichloromethane and ethylacetate might play a role on the anticanceric effect of doenjang.