• Title/Summary/Keyword: Mutant strain

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Isolation of Neutral Protease Hyperproducing Bacillus sp. KN103N and Some Properties of the Enzyme (中性 Protease 高 生産性 Bacillus sp. KN103N의 分離 및 酵素의 特性)

  • Kim, Hong-Rip;O, Pyong-Su
    • Microbiology and Biotechnology Letters
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    • v.19 no.2
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    • pp.116-121
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    • 1991
  • A bacterial strain KN, which highly produced a protease, was isolated from several soil samples and identified to to belong to the genus Bacillus. We selected mutant strain Bacillus sp. KN103N, which was hyperproducer of protease and was resistant to D-cyclowerine, from the strain KN by several steps of mutagenesis. Neutral protease productivity of mutant strain KN103N was about 55 times as much as that of the original strain KN. The optimum pH and temperature for the enzyme activity were 7.0 and 50$^{\circ}C$, respectively and the enzyme was relatively stable at pH6.0~8.0 and below 40$^{\circ}C$. The enzyme was inactivated by EDTA, but not by DFP. These results indicate that the enzyme from Bacillus sp. KN103N was a neutral (metallo-) protease.

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Screening of Bacillus sp. No. M-71 with High Alkaline Protease Productivity and Some Properties of the Enzyme (Alkaline Protease 고 생산성 세균의 선별 및 효소 특성)

  • 오성훈;오평수
    • Microbiology and Biotechnology Letters
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    • v.19 no.1
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    • pp.1-7
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    • 1991
  • A bacterial strain No.71, which produced alkaline protease, was isolated from soil and identified to the genus Bacillus. With the successive mutation, a mutant strain No. M-71, having high alkaline protease productivity, was obtanined from the parental strain No 71. Alkaline protease productivity of mutant strain No. M-71 was about 50 times as much as that of the parental strain No.71. The enzyme preparations showed strong activities toward casein, the optimum pH being 11.0 and the optimum temperature about $55^{\circ}C$.

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Fungal Strain Improvement for Cellulase Production Using Repeated and Sequential Mutagenesis

  • Vu, Van-Hanh;Pham, Tuan-Anh;Kim, Keun
    • Mycobiology
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    • v.37 no.4
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    • pp.267-271
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    • 2009
  • A fungal strain producing a high level of cellulase was selected from 320 fungal isolates and identified as Aspergillus sp. This strain was further improved for cellulase production by sequential treatments by two repeated rounds of $\gamma$-irradiation of $Co^{60}$, ultraviolet treatment and four repeated rounds of treatment with N-methyl-N'-nitro-N-nitrosoguanidine. The best mutant strain, Aspergillus sp. XTG-4, was selected after screening and the activities of carboxymethyl cellulase, filter paper cellulase and $\beta$-glucosidase of the cellulase were improved by 2.03-, 3.20-, and 1.80-fold, respectively, when compared to the wild type strain. After being subcultured 19 times, the enzyme production of the mutant Aspergillus sp. XTG-4s was stable.

Characterization of Brewing Yeast Expressing Glucoamylase Selected by Rare Mating. (Rare Mating에 의한 양초효모에서의 glucoamylase 발현 균주 HCS 선별 및 특성)

  • 최병주;장금일;김광엽
    • Microbiology and Biotechnology Letters
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    • v.29 no.4
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    • pp.212-220
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    • 2001
  • Rare mating was used to select a respiratory deficient mutant of Saccharomyces cerevisiae HDC52 strain. Glucoamylase gene of S. diastaticus K114 was developed into the RD mutant which could uptake maximum amount of non-fermentable sugars through the expression of glu- coamplyase gene and the fermentation characteristics of the developed strain HCS were investigated. The size of HCS yeast and HBD52 yeast strain were 13 $\mu\textrm{m}$ and 10$\mu\textrm{m}$ respectively. HCS strain which can uptake maximum amount of non-fermentable sugar through the expression of glucoamylase gene was developed. By karyotype anal- ysis. HCS stain but not RD mutant HBC52 showed a band of 1150 kb chromosome DNA This band should include glcoamylase gene from Saccharomyces diataticus K114 THis strain has glucoamylase which can degrade starch By transduction and contrnuance of glucoamylase gene HCS strain gegraded strach and formed halo. Also, HCS strain maintained the character after 50 generations. Glucoamylase activities of Saccharomyces diastaticus K114 and HCS yeast strains are 9.5 and 2.7~3.4(unit/ml) HCS and HBC52 strain showed similar sugar fermentation patterns and low flocculation In spore and film forming test, HCS and HBC52 strain formed neither spores nor films. In the limit fermentation test, HBC52 strain showed fermentation level of 68% and HCS strain showed 76~78% As the limit attenuation of HBC52 and HCS were ($2.00^{\circ}$P) and ($0.7~0.93^{\circ}$P) This study demon- strates and HCS strain may be used for low carbohydrate beer fermentation.

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Site-specific Disruption of Glyoxylate Bypass and Its Effect in Lysine-producing Corynebacterium lactofermentum Strain

  • Kim, Youn-Hee;Lee, Heung-Shick
    • Journal of Microbiology and Biotechnology
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    • v.6 no.5
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    • pp.315-320
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    • 1996
  • The role of glyoxylate bypass in a lysine-producing Corynebacterium lactofermentum strain was analyzed. Unlike the wild type, the strain expressed enzymes of glyoxylate bypass during growth in the fermentation broth containing glucose as the carbon source. To evaluate the importance of glyoxylate bypass in the strain, we disrupted chromosomal aceA by using a cloned fragment of the gene. Site-specific disruption of aceA which codes for the isocitrate lyase, the first enzyme of the bypass, was confirmed by Southern blot analysis. The aceA mutant strain completely lost isocitrate lyase activity and ability to grow in a minimal medium containing acetate as the sole carbon source. The mutant strain was similar to its parental strain in growth characteristics and produced comparable amounts of lysine in shake flasks containing glucose as the carbon source. The amount of oxaloacetate accumulated in the fermentation medium was similar for both strains, suggesting that expression of glyoxylate bypass does not necessarily lead to the increase in intracellular oxaloacetate. These data clearly demonstrate that glyoxylate bypass does not function as one of the routes of carbon supply for lysine production in the strain. It appears that the leakiness of the glyoxylate bypass in the strain might be the result of a secondary mutation which arose during previous strain development by random mutagenesis.

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Optimization of Penicillin Amidase Production and A Simplified Enzyme Assay Method (페니실린 아미다제 생산의 최적 조건 및 간이화한 효소 정량 방법에 대한 연구)

  • 김경훈;유두영
    • Korean Journal of Microbiology
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    • v.15 no.4
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    • pp.145-153
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    • 1977
  • Penicillin amidase (EC 3.5.1.11) was produced by a mutant strain of Bacillius megaterium ATCC 14945. Hydroxylamine assay method for the determination of 6-APT was modified by using "HCl addition techniques" in order to simplify the time consuming orginal assay method without sacrifice of accuracy. Using the new mutant strain, the effects of fermentation conditions on enzyme production were studied.e studied.

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Characterization of the Mutant of Streptomyces sp. SL-387(KCTC 0102BP) Producing Aminopeptidase M Inhibitors (Aminopeptidase M 저해제를 생산하는 Streptomyces sp. SL-387 (KCTC 0102BP) 변이주의 특성)

  • Chung, Myung-Chul;Chun, Hyo-Kon;Lee, Ho-Jae;Lee, Choong-Hwan;Kho, Yung-Hee
    • Microbiology and Biotechnology Letters
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    • v.23 no.1
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    • pp.47-52
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    • 1995
  • Since the original productivity of new aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 (KCTC 0102BP) was not enough for further chemical and biological evaluation, mutation of parent strain by the treatment of N-methyl-N'-nitro-N-nitrosoguanidine was performed in order to obtain a clone with greater inhibitory activity. Mutant N-3 was selected due to a 6-fold greater productivity (40 $\mu$g/ml) than that of the wild type(6.7 $\mu$g/ml). This mutant was resistant to 3,4-dehydro-DL-proline, an antimetabolite of proline, with 25 $\mu$g/ml of minimum inhibitory concentration. Furthermore, the characteristic morphological change from spiral spore chain in wild type to straight in mutant was observed. An aminopeptidase M nhibitor different from MR-387A and B was isolated from the culture broth of the mutant. This inhibitor was composed of 2 proline, 1 valine, and an unknown amino acid which is presumably 3-amino-4-phenylbutanoic acid. IC$_{50}$ value (89.1 $\MU$g/ml) of the purified inhibitor was lower than that of other inhibitors, which may be due to the absence of 2(S)-hydroxyl group within the structure of 3-amino-4-phenyl- butanoic acid.

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Isolation and Proteomic Analysis of a Chlamydomonas reinhardtii Mutant with Enhanced Lipid Production by the Gamma Irradiation Method

  • Baek, Jaewon;Choi, Jong-il;Park, Hyun;Lim, Sangyong;Park, Si Jae
    • Journal of Microbiology and Biotechnology
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    • v.26 no.12
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    • pp.2066-2075
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    • 2016
  • In this study, an enhanced lipid-producing mutant strain of the microalga Chlamydomonas reinhardtii was developed by gamma irradiation. To induce the mutation, C. reinhardtii was gamma irradiated at a dose of 400 Gy. After irradiation, the surviving cells were stained with Nile red. The mutant (Cr-4013) accumulating 20% more lipid than the wild type was selected. Thin-layer chromatography revealed the triglyceride and free fatty acid contents to be markedly increased in Cr-4013. The major fatty acids identified were palmitic acid, oleic acid, linoleic acid, and linolenic acid. Random amplified polymeric DNA analysis showed partial genetic modifications in Cr-4013. To ascertain the changes of protein expression in the mutant strain, two-dimensional electrophoresis was conducted. These results showed that gamma radiation could be used for the development of efficient microalgal strains for lipid production.

Interaction Between the Quorum Sensing and Stringent Response Regulation Systems in the Enterohemorrhagic Escherichia coli O157:H7 EDL933 Strain

  • Oh, Kyung-Hwan;Cho, Seung-Hak
    • Journal of Microbiology and Biotechnology
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    • v.24 no.3
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    • pp.401-407
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    • 2014
  • Quorum sensing and the stringent response are well-known regulation systems for the expression of virulence genes in enterohemorrhagic Escherichia coli (EHEC). However, how these two systems interact is not well known. E. coli strains with mutations in two regulation systems, ${\Delta}luxS$ (ECM101) and ${\Delta}luxS{\Delta}relA{\Delta}spoT$ (ECM201), and the ${\Delta}luxS$ complement strain to ECM201 (ECM202) were created from EHEC O157:H7 EDL933 to investigate how the regulatory systems interact. The phenotypic changes of the mutant strains were characterized and compared with the wild type. The mutant strains exhibited no obvious growth defects, although acid resistance and cellular cytotoxicity were decreased significantly in all the mutant strains. Phenotypic characterization revealed that mutations in the stringent response system (ECM201 and ECM202) influenced the metabolic (defective utilization of arabinose and L-sorbose) and enzymatic activities (decreased trypsin activity, and increased ${\alpha}$-glucosidase activity). In contrast, the quorum sensing system mutant (ECM101) did not display these phenotypes. The motility of the quorum sensing system mutant (ECM101) was unchanged, but mutation in the stringent response system influenced the motility. Our results suggest that quorum sensing interacts with the stringent response regulation system.

The Mutant Lactobacillus plantarum GNS300 Showed Improved Exopolysaccharide Production and Antioxidant Activity

  • Jae-Youn Jung;Deok-Ho Kwon;Yoo Jin Lee;Young Keun Song;Moon Sik Chang;Suk-Jin Ha
    • Microbiology and Biotechnology Letters
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    • v.51 no.1
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    • pp.18-25
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    • 2023
  • After random mutagenesis, the mutant Lactobacillus plantarum GNS300 showed improved exopolysaccharide production as determined by the quantification of total sugar. The mutant L. plantarum GNS300 produced 2.82 g/l of exopolysaccharide which showed 79.62% improved exopolysaccharide production compared with the parental strain. When exopolysaccharide of L. plantarum GNS300 was analyzed, the exopolysaccharide is composed of galactose (93.35%) and glucose (6.65%). Through the optimization of fermentation conditions using a bioreactor, 2.93 g/l of exopolysaccharide was produced from 20 g/l of glucose at 35℃, 500 rpm, and 0.1 vvm for 12 h. The mutant L. plantarum GNS300 exhibited 69.18% higher antioxidant activity than that from the parental strain, which might be caused by higher exopolysaccharide production. The concentrated supernatant of the mutant L. plantarum GNS300 inhibited the growth of gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) and gram-negative bacteria (Escherichia coli, Vibrio parahaemolyticus, and Salmonella typhimurium).