• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.541-546
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• 1990

Bacillus sphaericus ts-Dl290 was characterized by SDS-PAGE produced by the mutant at $30^{\circ}C$ and $42^{\circ}C$. The total amount of proteins produced by the mutant at $42^{\circ}C$ decreased to one-fifth of those at $30^{\circ}C$; however, when the culture was shifted down from $42^{\circ}C$ after 4 to $30^{\circ}C$, the total amount of protein decreased to one-third and the 221 kd protein did not appear, but the 155 kd appeared remarkably. When the mutant and the wild type strain were cultured in the media containing 80$\mu g$ per ml of chloramphenicol at $42^{\circ}C$, the wild type strain synthesized half amounts of the total proteins than those at $30^{\circ}C$, and the mutant produced one-tenth of the total protein amounts. When the both strains were cultured in the media containing chloramphenicol, the 155 kd protein was produced was produced in lesser amounts than those without chloramphenicol. The 150 kd protein showed lethal activity to Culex pipiens 3rd instar larvae.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.203-208
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• 1985

Partial characterization of B. thuringiensis var. kurstaki 3ab temperature-sensitive mutants was carried out through biochemical analyses, utilization tests of carbohydrate sources, antobiotic resistant test, hemolytic reaction test, growth measurement of Fructus gardenia sxtrant medium and toxicity test against mice. Six ts mutants, ts-U154, ts-U601, ts-U602, ts-U603, tsU-604, and ts-U788 could not produce urease, ts-U603 lost its motility, ts-U154 could not use salicin and cellobiose and ts-U603 not ribose. All ts mutants except ts-U154 and wild type strain were resistant to cephalothin, ampicillin, and penicillin. but ts-U154 was sensitive to the three. Four mutants, ts-U21, ts-U74, ts0U131 and ts-U154 did not form pigment colonies on the F. gardenia medium. All the mutants and wild type strain showed hemolysis reaction on the blood agar. The B. thuringiensis and mutants were not toxic to mice.

• Journal of Mushroom
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• v.13 no.2
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• pp.92-96
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• 2015

'Geumhyang', a new variety with short cultivation period and yellowish ivory color in Flammulina velutipes, was bred by crossing between monokaryons isolated from 'Garlmoe' and wild strain 'CBMFV-33'. In bottle cultivation, the period of mycelial growth, primordia1 formation, and growth of fruit body was required 23 days, 7 days, and 17 days, respectively. Total culvivation period was 47 days, showing 7 days shorter than that of 'Garlmoe'. Pileus diameter was greater than that of 'Garlmoe', and pileus color showed yellowish ivory. Fruit body production per 850 ml bottle was 160 g, which was 8% higher than that of 'Garlmoe'. The taste, derived from 'Garlmoe' and wild strain, was excellent because of better chewing feeling than white ones. 'Geumhyang' with differentiated color and taste, has an advantage to target a niche market of white ones.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1324-1326
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• 2004

In previous studies, we isolated an isogenic LPS mutant of Bradyrhizobium japonicum 61A101C, which was completely devoid of O-polysaccharide and had altered cell surface characteristics. Subsequently, the mutated gene was identified, cloned, and used to complement the LPS mutant strain JS314 to restore the phenotype. Since it has been reported that in Escherichia coli LPS O-polysaccharide is involved in resistance to an organic acid such as acetic acid under low pH (Barna et al., Molecular Microbiology 43: 629-640, 2002), we compared the organic acid resistance of the three B. japonicum strains; wild-type 61A101C, the LPS mutant JS314, and the complemented strain to determine whether the role of O-polysaccharide in the resistance to organic acid could be generalized. Growth of all three strains was inhibited by the presence of 3 mM acetic acid under acidic condition (pH 5.5). To our surprise, however, in the presence of 2 mM acetic acid, wild-type and the complemented strains did not grow while the $LPS^-$ mutant showed a significant growth. Therefore, unlike in E. coli, the lack of O­polysaccharide of LPS appears to render B. japonicum more resistant to organic acid.

• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1311-1319
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• 2016

Alternaria brassicicola (Schwein.) invades Brassicaceae and causes black spot disease, significantly lowering productivity. Mitogen-activated protein kinases (MAPKs) and their upstream kinases, including MAPK kinases (MAPKKs) and MAPKK kinases (MAPKKK), comprise one of the most important signaling pathways determining the pathogenicity of diverse plant pathogens. The AbSte7 gene in the genome of A. brassicicola was predicted to be a homolog of yeast Ste7, a MAPKK; therefore, the function was characterized by generating null mutant strains with a gene replacement method. AbSte7 replacement mutants (RMs) had a slower growth rate and altered colony morphology compared with the wild-type strain. Disruption of the AbSte7 gene resulted in defects in conidiation and melanin accumulation. AbSte7 was also involved in the resistance pathways in salt and oxidative stress, working to negatively regulate salt tolerance and positively regulate oxidative stress. Pathogenicity assays revealed that AbSte7 RMs could not infect intact cabbage leaves, but only formed very small lesions in wounded leaves, whereas typical lesions appeared on both intact and wounded leaves inoculated with the wild-type strain. As the first studied MAPKK in A. brassicicola, these data strongly suggest that the AbSte7 gene is an essential element for the growth, development, and pathogenicity of A. brassicicola.

• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.801-804
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• 2013

The glutathione contents of the selected mutants were investigated and found to be 6.1-15.8 mg/g-DCW. The glutathione content positively correlated with the antioxidant activity of the mutant strains ($R^2$=0.488). Furthermore, the glutathione content of the mutant S. cerevisiae Sa-59 was approximately 38% greater than that of the wild type strain and, therefore, this mutant strain was selected for glutathione production. The volumetric glutathione content in a shaking culture was increased by about 70% compared to the static culture. In addition, the specific glutathione content was increased by ~19%. The volumetric glutathione content and specific glutathione content were increased by approximately 16% and 66%, respectively, when 0.04% glutamate, 0.04% cysteine and 0.04% glycine were added. Furthermore, the highest antioxidant activity was 0.52 as absorbance unit at 700 nm.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1452-1459
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• 2007

The Dps protein, which is overexpressed in harsh environments, is known to playa critical role in the protection of DNA against oxidative stresses. In this study, the roles of Fur in the expression of the dps gene in Salmonella and the protection mechanisms against oxidative stress in Salmonella cells preexposed to iron-stress were investigated. Two putative Fur boxes were predicted within the promoter region of the S. typhimurium dps gene. The profile of dps expression performed by the LacZ reporter assay revealed growth-phase dependency regardless of iron-status under the culture conditions. The fur mutant, $_X4659$, evidenced a reduced level of ${\beta}$-galactosidase as compared to the wild-type strain. The results observed after the measurement of the Dps protein in various Salmonella regulatory mutants were consistent with the results acquired in the reporter assay. This evidence suggested that Fur performs a function as a subsidiary regulator in the expression of dps. The survival ability of Salmonella strains after exposure to oxidative stress demonstrated that the Dps protein performs a pivotal function in the survival of stationary-phase S. typhimurium against oxidative stress. Salmonella cells grown in iron-restricted condition required Dps for full protection against oxidative stress. The CK24 (${\Delta}dps$) cells grown in iron-replete condition survived at a rate similar to that observed in the wild-type strain, thereby suggesting the induction of an unknown protection mechanism(s) other than Dps in this condition.

• Journal of Microbiology and Biotechnology
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• v.16 no.2
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• pp.312-317
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• 2006

The chromosomal sprD gene encoding Streptomyces griseus protease D (SGPD), a chymotrypsin-like protease, was disrupted in Streptomyces griseus by insertion of the neomysin-resistance gene. The production of chymotrypsin activity of sprD disruptant was not completely abolished, but delayed by 24 h, compared with that of wild-type strain. The aerial mycelial formation of sprD disruptant was retarded, and specifically the formation of spores was not observed in the central region of colonies. However, normal morphological development into spores was observed in the marginal region of colonies. In addition, the production of yellow pigment that might be dependent on A-factor was also decreased in the sprD disruptant, compared with that of the wild-type strain. Introduction of the sprD gene, which was placed on a high copy-numbered plasmid into S. griseus ${\Delta}sprD$, partially restored the ability of morphological development, and a significant level of sporulation was observed. When the overexpression vector for sprD, pWHM3-D, was introduced in S. griseus, there was no significant change in the chymotrypsin activity or colonial morphology, in contrast to Streptomyces lividans, indicating the presence of a tight regulation system for the overexpression of the sprD gene in S. griseus.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.11a
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• pp.65-73
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• 1996

LPS/LOS, the compound found only in gram-negative bacterial outer membrane, plays important roles in bacterial maintenance as well as its pathogenesis. We isolated and characterized several genes required for NTHi 2019 LOS biosynthesis, which encode enzymes required for sugar substrate synthesis or the transfer of substrates to receptor molecules. The htrB gene, however, appears to have more complex role. It has acryltransferase activity as well as various other activity, which may control regulation of LOS biosynthesis as well as its pathogenicity. Evidences supporting the latter come from the observations that the lipid A of the B29 induced significantly less TNF ${\alpha}$ from macrophages than that of the wild type LOS (unpublished data). H. influenzae A2-htrB mutant strain was also significantly less invasive than the wild type strain. The structural similarities of the enterobacterial LPS and the Haemophilus LOS enabled us to isolate the NTHi 2019 genes involved in LOS biosynthesis genes by using the S. typhimurium LPS deep core mutants. While a similar approach has been used for E. coli, this technique for selection of an LPS phenotype has not been applied to nonenterobacterial species. The difficulties inherent in the molecular manipulation of organism such as Neisseria and Haemophilus species make this approach particularly attractive in the identification and cloning LOS genes. Studies on genetic features of LPS/LOS biosynthesis would be useful for understanding bacterial pathogenesis as well as for developing vaccines for these gram-negative pathogenic bacteria.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.142-146
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• 2000

Ordered differential display using RT-PCR (ODD-PCR) was conducted to have a profile of the differently expressed genes between a hypovirulent strain of Cryphonectria parasitica (UEP1) and its isogenic wild type strain (EP155/2). ODD-PCR has advantages of high sensitivity, reproducibility, proportional representation, and limited number of primer combinations comparing with other differential display methods. RNAs were prepared from 1 and 5 day liquid culture of both hypovirulent and wild type strains, and were further evaluated with the marker genes of C. parasitica such as cryparin and mating factor MF2-1, which were already proven to be specifically down-regulated by the presence of mycovirus CHV1-713. ODD-PCR was conducted using those RNAs and expressed genes were categorized to five groups according to their temporal and quantitative expression patterns. Those fives groups are CPC, CPE, CPL, CPD, and CPU which represent constitutively-expressed, early-expressed, late-expressed, down-regulated, and up-regulated, respectively. Ninety two primer combinations out of a total of 192 have been tested so far. Among the twenty to fifty distinct bands per each reaction, an average of four to ten genes was identified as viral-regulated fungal genes. Those viral-specifc genes were further analyzed by DNA sequencing followed by homology search. Characterization of 30 clones including all five groups were conducted as a preliminary data and more are under investigation.