• Korean Journal of Microbiology
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• v.47 no.4
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• pp.289-294
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• 2011

We investigated the cold shock sensitivity of DEAD-box RNA helicase gene deleted strains of in Bacillus subtilis CU1065. To understand cold shock effects, cells were cultivated at $37^{\circ}C$ to log phase ($O.D_{600}$=0.5-0.6) and then temperature was shifted to $15^{\circ}C$. Cold shock slow down the growth rate of wild type and deleted strains of DEAD-box RNA helicase gene (ydbR, yfmL, yqfR, deaD). The growth rate of ydbR deleted strain is 5 times severely reduced compared to that of wild type strain (CU1065). But the growth rate of other three (yfmL, yqfR, deaD) deleted strains is nearly equal to the growth rate of wild type. Compared to $37^{\circ}C$, the amount of ydbR and yqfR mRNA transcripts are increased at the growth temperature of $15^{\circ}C$. On the other hands the mRNA transcripts of yfmL and deaD are not changed at both conditions of $37^{\circ}C$ and $15^{\circ}C$. Upon cold shock treatment ydbR mRNA transcript is clearly increased. After treatment of rifampicin (bacteria transcription inhibitor) the amount of ydbR mRNA was measured. Temperature shift from $37^{\circ}C$ to $15^{\circ}C$ and rifampicin treatment showed slowly decay of ydbR mRNA. But at $37^{\circ}C$ and rifampicin treatment ydbR mRNA is rapidly reduced. These results showed that cold shock induction of ydbR mRNA resulted from the stability of ydbR mRNA and not from the transcription induction of ydbR. In relation to these results, we found the cold box element of csp (cold shock protein gene) in 5' untranslated region of ydbR gene. Cold shock induction of ydbR is caused by the stability of ydbR mRNA like the stability of csp mRNA.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.170-175
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• 2023

In this study, the effect of MnSO₄ on the insecticidal crystal (IC) produced by Bacillus thuringiensis for a rapid detection medium was analyzed. The strains used included one B. thuringiensis reference (KCTC 1511) and nine wild-type strains. The IC in B. thuringiensis was detected following the method published by the Ministry of Food and Drug Safety in Korea. In the nutrient agar to which 0.005% MnSO₄ was added, IC was observed on two of the three plates after 48 hours of incubation and on all three plates after 120 hours. In AK agar, IC was observed on one and two of the three plates after 48 and 96 hours of incubation, respectively. These results indicated that 0.005% MnSO₄ nutrient agar is more appropriate than AK agar for production of IC in B. thuringiensis. The effect of various MnSO₄ concentrations on IC production was studied after 24 hours of incubation. IC was produced on 1 of the 10 plates with 0.000% MnSO₄ nutrient agar, 2 of the 10 plates with 0.001% MnSO₄ nutrient agar, and 3 of the 10 plates with 0.002% MnSO₄ nutrient agar. IC was not observed for the other nutrient agars containing 0.003%-0.009% MnSO₄. These results indicated that nutrient agar with 0.002% MnSO₄ led to the most rapid production of IC by B. thuringiensis after 24 hours of incubation. However, the conditions for IC production by B. thuringiensis depended on the incubation conditions and strain activity. Therefore, further studies are needed to verify the effects of 0.002% MnSO₄ on the production of IC by various Bacillus thuringiensis strains.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.6
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• pp.833-838
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• 2013

In this study, twelve strains of brewing fungi were individually cultivated on wheat extract broth (WEB), potato dextrose broth (PDB) and malt extract broth (MEB) in order to determine the microorganism with good culture characteristics as well as with amylolytic activity. The strain cultured in PDB exhibited mycelia production from 12.6 g/L (Rhizopus oryzae KACC 45714) to a maximum of 48.0 g/L (Aspergillus oryzae KACC 46959), which was 2.3~9.2 times lower than that of the strain cultured in WEB and 1.7~14.6 times lower than that of the strain cultured in MEB. Accorfing the results, We found that the commercial strains of A. oryzae Suwon, CF1001 and CF1003 had a higher dry cell mass than the wild-type strains KACC 46421, 46423, 46424 and 46959. For Rhizopus sp., the acidity levels in WEB, PDB and MEB were 0.12~0.47%, 0.22~1.0% and 0.16~0.68% (equivalent lactic acid concentration) respectively. For A. oryzae, the acidity levels were 0.06~0.11%, 0.03~0.04% and 0.06~0.08% (equivalent lactic acid concentration), respectively. Amylase enzyme from Rhizopus delemar KACC 46419 exhibited an enzyme activity of 0.013 U and 0.019 U in WEB and MEB cultures, respectively. The enzyme activity of the amylase enzyme from A. oryzae was 0.019~0.037, 0.017~0.033 and 0.028~0.046 U in WEB, PDB and MEB cultures, respectively.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.533-541
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• 2000

Biochemical and genetic analysis were carried out to investigate the potential recovery of pathogenecity or related mutations of Brucella abortus RB51 vaccine strains. RB51 strains were recovered from commercial vaccines, including related seed stocks from private companies in Republic of Korea, strain from USA, a reference strain from C university and a field isolate (Daehungjin) from aborted dairy cow after RB51 vaccination were compared with two identified virulent wild strains (S2308 and a field strain isolated from dairy cow in Korea) at the same conditions. All the strains examined, except identified pathogenic strains, revealed the identical characteristics to the original RB51 in biochemical properties, antigen and bacteriophage typing. Outer membrane protein (OMP) profiles from strains of RB51 showed the same patterns with standard RB51 in SDS-PAGE. In addition, Western blotting with the brucella specific monoclonal antibody also indicated that all the vaccine strains were completely deficient in their LPS compared to the pathogenic Br abortus strains. The differences in DNA structures among strains were also possible to detect after PCR. All vaccine strains, except S19, S1119-3, S1075, S544 and Br suis, were amplified a 178bp DNA fragment of eri-gene, and 364bp of IS711 elements. In contrast, 498bp DNA product was only found with Br abortus. Overall evidences in the present study confirmed that the RB51 strains for vaccine production in Korea did not originated from the phenomena of possible recovery of pathogenicity or related to any potential mutation event at all.

• Smart Structures and Systems
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• v.21 no.5
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• pp.687-694
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• 2018

The problem of wheel tread defects has become a major challenge for the health management of high-speed rail as a wheel defect with small radius deviation may suffice to give rise to severe damage on both the train bogie components and the track structure when a train runs at high speeds. It is thus highly desirable to detect the defects soon after their occurrences and then conduct wheel turning for the defective wheelsets. Online wheel condition monitoring using wheel impact load detector (WILD) can be an effective solution, since it can assess the wheel condition and detect potential defects during train passage. This study aims to develop an FBG-based track-side wheel condition monitoring method for the detection of wheel tread defects. The track-side sensing system uses two FBG strain gauge arrays mounted on the rail foot, measuring the dynamic strains of the paired rails excited by passing wheelsets. Each FBG array has a length of about 3 m, slightly longer than the wheel circumference to ensure a full coverage for the detection of any potential defect on the tread. A defect detection algorithm is developed for using the online-monitored rail responses to identify the potential wheel tread defects. This algorithm consists of three steps: 1) strain data pre-processing by using a data smoothing technique to remove the trends; 2) diagnosis of novel responses by outlier analysis for the normalized data; and 3) local defect identification by a refined analysis on the novel responses extracted in Step 2. To verify the proposed method, a field test was conducted using a test train incorporating defective wheels. The train ran at different speeds on an instrumented track with the purpose of wheel condition monitoring. By using the proposed method to process the monitoring data, all the defects were identified and the results agreed well with those from the static inspection of the wheelsets in the depot. A comparison is also drawn for the detection accuracy under different running speeds of the test train, and the results show that the proposed method can achieve a satisfactory accuracy in wheel defect detection when the train runs at a speed higher than 30 kph. Some minor defects with a depth of 0.05 mm~0.06 mm are also successfully detected.

• Journal of Life Science
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• v.7 no.1
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• pp.30-38
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• 1997

For screening thermostable $\alpha$-amylase from thermophiles, various samples from extreme environments such as hot spring and sewage near them, and compoat, wereexamined microbial growth in enrichment culture medium at 55$\circ$C on the assumption that enzymes from thermophiles are inevitable thermostable. One strain showing higher $\alpha$-amylase activity was pure cultured and designated as Bacillus sp. TR-25 from the results of morphological, cultural and physiological characteristics. The most important carbon sourses for the enzyme production were soluble starch, dextrin, potato starch and corn starch. Glucose and fructose had a catabolite repression on the enzyme production. The good nitrogen sources for the enzyme production were yeat extract, nutrient broth, tryptone, corn steep liquor and ammonium sulfate. The enzyme production was accelerated by addition of CaCl$_{2}$. $\cdot $ H$_{2}$O. The optimal medium composition for the enzyme production was soluble starch 2.0%, yeast extract 0.55, CaCl$_{2}$ $\cdot $ 2H$_{2}$O 0.015, Tween 80 0.001%, pH8.0, respectively. In jar fermenter culture, this strain shows a rapid growth and required cheaper carbon and nitrogen source. These properties are very useful to fermentation industry. The $\alpha$-amylase of this strain demonstrated a maximum activity at 80$\circ$C, pH 5.0, respectively. And calcium ion did not improve thermostability of the enzyme. At 10$0^{\circ}C$, this enzyme has 235 of relative activity. Transformation was carried out by thermophilic Bacillus sp. TR-25 genomic DNA. As a result, the transformant has increased thermostable $\alpha$-amylase activity.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.955-960
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• 2005

Resistance to metronidazole, a key component of therapies against Helicobacter pylori, is common in clinical isolates. Resistance generally requires inactivation of rdxA (HP0954), and sometimes also frxA (HP0642), two related nitroreductase genes. Here we studied the effect of resistance to metronidazole on fitness of the gastric pathogen H. pylori. The effect of metronidazole resistance for H. pylori in culture was assessed first by looking at colonies formed by freshly constructed mutant derivatives of H. pylori strain 26695. Mutations resulting in metronidazole resistance caused premature death of H.pylori in stationary phase, but had no significant effect on early exponential growth. The effect of nitroreductase deficiencies on fitness in vivo was tested by infecting C57BL/6 mice with 1:1 mixtures of SS1 wild type and its isogenic metronidazole resistant derivatives. Inactivation of rdxA caused an inability to colonize mice in SS1 H. pylori strain. Derivatives of a metronidazole resistant strain that survived better in stationary phase, although remaining metronidazole resistant, could again colonize mice. In conclusion, metronidazole resistance diminishes H. pylori's fitness, but their costs can be suppressed by additional mutation.

• Food Science and Preservation
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• v.18 no.4
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• pp.604-611
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• 2011

Several wild yeasts were isolated from Korean grape varieties before and during spontaneous fermentation. Among them, four strains were isolated based on the alcohol content and flavor production in wine after fermentation of apple juice. In this study, the four yeast strains were identified and characterized. PCR-restriction fragment length polymorphism analysis of ITS I-5.8S-ITS II region with restriction endonuclease Hae III and Hinf I resulted in that all the strains showed a typical pattern of Saccharomyces cerevisiae. Pulse field gel electrophoresis showed three different chromosome patterns with a same band between strains SS89 and SS812. When ITS I-5.8S-ITS II sequences of the four strains were compared with one another, they were similar to those of Saccharomyces cerevisiae CBS 4054 type strain. Identity of the sequences was higher than 97% with those of the type strain. Phylogenetic analysis showed based on the sequences showed they were genetically closed to the type strain. The four identified strains were tested in a medium containing 200 ppm potassium metabisulfite, and the MM10 and WW108 inhibition rates resulted at up to 24 h. The four strains were tested at an incubation temperature of $30^{\circ}C$. The 30% sugar concentration in the medium (w/v) showed the highest growth in 36 h, especially in the case of SS89, which was close to growth 40. The four strains were tested in an 8% ethanol medium (v/v). Alcohol tolerance was initially kept in the incubation process. The strains began to adapt, however, to the exceeded resistance. The four strains showed the lowest inhibition rate at 24 h.

• Journal of Life Science
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• v.27 no.10
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• pp.1137-1144
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• 2017

The microalgae Chlorella vulgaris has been considered an important alternative resource for biodiesel production. However, its industrial-scale production has been constrained by the low productivity of the biomass and lipid. To overcome this problem, we isolated and characterized a potentially economical oleaginous strain of C. vulgaris via the random mutagenesis technique using UV irradiation. Two types of mass production systems were compared for their yield of biomass and lipid content. Among the several putatively oleaginous strains that were isolated, the particular mutant strain designated as UBM1-10 in the laboratory showed an approximately 1.5-fold higher cell yield and lipid content than those from the wild type. Based on these results, UBM1-10 was selected and cultivated under outdoor conditions using two different types of reactors, a tubular-type photobioreactor (TBPR) and an open pond-type reactor (OPR). The results indicated that the mutant strain cultivated in the TBPR showed more than 5 times higher cell concentrations ($2.6g\;l^{-1}$) as compared to that from the strain cultured in the OPR ($0.5g\;l^{-1}$). After the mass cultivation, the cells of UBM1-10 and the parental strain were further investigated for crude lipid content and composition. The results indicate a 3-fold higher crude lipid content from UBM1-10 (0.3%, w/w) as compared to that from the parent strain (0.1% w/w). Therefore, this study demonstrated that the economic potential of C. vulgaris as a biodiesel production resource can be increased with the use of a photoreactor type as well as the strategic mutant isolation technique.

• BMB Reports
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• v.40 no.5
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• pp.662-669
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• 2007

Although the function of cellular prion protein (PrP$^C$) and the pathogenesis of prion diseases have been widely described, the mechanisms are not fully clarified. In this study, increases of the portion of non-glycosylated prion protein deposited in the hamster brains infected with scrapie strain 263K were described. To elucidate the pathological role of glycosylation profile of PrP, wild type human PrP (HuPrP) and two genetic engineering generated non-glycosylated PrP mutants (N181Q/N197Q and T183A/T199A) were transiently expressed in human astrocytoma cell line SF126. The results revealed that expressions of non-glycosylated PrP induced significantly more apoptosis cells than that of wild type PrP. It illustrated that Bcl-2 proteins might be involved in the apoptosis pathway of non-glycosylated PrPs. Our data highlights that removal of glycosylation of prion protein provokes cells apoptosis.