• Title, Summary, Keyword: sporulation

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Development of an Efficient Screening Strategy for Rapid Selection of High-yielding Mutants of Itaconic Acid Biosynthesized by Fungal Cells of Aspergillus terreus (이타콘산 고생산성 Aspergillus terreus 변이주의 신속 선별을 위한 효율적인 균주 스크리닝 전략 개발)

  • Shin, Woo-Shik;Kim, Pyeung-Hyeun;Lee, Do-Hoon;Kim, Sang-Yong;Jeong, Yong-Seob;Chun, Gie-Taek
    • KSBB Journal
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    • v.26 no.3
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    • pp.229-236
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    • 2011
  • An efficient screening method was developed for rapid selection of a few overproducers of itaconic acid (IA) among the great many mutants derived from mother strains of Aspergillus terreus. For this purpose, an attempt was made to reveal the relationships of the growth rate and sporulation of each mutant on PDA solid medium with its IA productivity in the final liquid production-culture. As a result, it was possible to classify the mutated strains into 5 groups (from [A] to [E] group) according to theirmorphologies (i.e., growth rate and sporulation extent) on the PDA slants. Notably, most of the high-yielding mutants of IA were observed to belong to [A]group which had the properties of the highest growth rate and sporulation among the 5 groups, whereas the mutant groups of [C], [D] and [E] with the contrasting morphological features showed significant reductions in their IA productivities. From these results, it was concluded that the probability of selecting IA overproducing mutants could be remarkably enhanced when the mutated colonies showing faster growth rates are firstly selected on the PDA plate, and then further screening process is performed on the basis of the sporulation extents of the mutants selected. Consequently, through the application of the strategy developed in this study, costs and time involvedin the labor-intensive task of strain improvement could be reduced to a great extent, because the time-consuming liquid culture processes did not need to performed for the unfavorable mutants belonging to the groups other than group [A].

Factors Affecting Sporulation, Germination, and Appressoria Formation of Epicoccosorus nematosporus as a Mycoherbicide Under Controlled Environments

  • Hong, Yeon-Kyu;Cho, Jae-Min;Lee, Bong-Choon;Uhm, Jae-Youl;Kim, Soon-Chul
    • The Plant Pathology Journal
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    • v.18 no.1
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    • pp.50-53
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    • 2002
  • To develop Epicoccosorus nematosporus as a mycoherbicide of Eleocharis kuroguwai, the optimum temperature and humidity for sporulation of the pathogen were studied. Conidial production was most abundant at $28^{\circ}C$ with RH 60%, which yielded 661 mg in 9 cm Petri dish. Light intensity of 3,000 up to 7,500 lux was effective in stimulating conidial production of E. nematosporus on oatmeal agar, Light intensity affected sporulation more significantly than temperature. In the pot test, at least 12 h of dew period at $20^{\circ}C$ and $25^{\circ}C$ was required to achieve satisfactory conidial germination and appressorial formation. Few were killed at 8 h of dew period regardless of temperature. Sixteen hours of a single dew treatment immediately after inoculation killed more plants than did two or three repetitive dew treatments of 8-12 h.

Evaluation of Electrolyzed Oxidizing Water as a Control Agent of Cucumber Powdery Mildew

  • Lee, Yong-Hwan;Cha, Kwang-Hong;Ko, Sook-Ju;Park, In-Jin;Park, Boung-In;Seong, Ki-Young
    • The Plant Pathology Journal
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    • v.16 no.4
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    • pp.206-210
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    • 2000
  • The effect of the electrolyzed oxidizing water on Sphaerotheca fuliginea was investigated with germination and sporulation of the fungal conidia. The sporulation was inhibited by the electrolyzed oxidizing water of pH 2.5, 3.5, and 4.5, but was not inhibited by the distilled water adjusted pH with 1N-HCL solution. However, the electrolyzed oxidizing water did not affect conidial germination. The oxidation-reduction potential at pH 2.5 and pH 3.5 of electrolyzed oxidizing water were 1130 mV and 1060 mV, respectively, but those of distilled water adjusted with HCL solution were 550 mV and 490 mV, respectively. When the electrolyzed oxidizing water of ORP over 1100 mV was sprayed on cucumplanting, the disease severities of powdery mildew were about 8.5% and 19.2%, respectively. Disease severity of a standard control (triflumizole 30% WP, $500\textrm{mg}\textrm{/L}$) was about 3.0%, while that of plants without electrolyzed oxidizing water was to 45.8%.

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Myxococcus xanthus socD500 mutation causes Sporulation and Induction of two C-signal Specific Genes (Myxococcus xanthus socD500에 의한 포자 형성 및 CsgA신호에 특이적 유전자의 발현에 관한 연구)

  • 이병욱
    • Journal of Life Science
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    • v.13 no.2
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    • pp.184-190
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    • 2003
  • Myxococcus xanthus is a Gram negative, rod-shaped, soil bacterium that displays a social behaviors, and multicellular development upon nutrient deprivation. The csgA gene encoding a cell surface protein is essential for developmental behaviors including rippling, aggregation, fruiting body formation and sporulation. csgA mutants show normal vegetative growth, but lack all these developmental phenotypes. Expression of the CsgA (C-signal) specific genes are eliminated or dramatically reduced in csgA mutants. In order to identify components of C-signal transduction pathway, second site mutations were introduced into csgA mutants and were identified which can fully or partially restore development of csgA mutants (Rhie, H. G. et. al. 1989. J. Bacteriol. 171, 3268-3276). One of such csgA suppressor mutations, socD500 restores only sporulation to csgA mutants at 15$^{\circ}C$. The socD500 mutaion however eliminates the three basic developmental requirements, starvation, high cell density and a solid surface. Only sporulation, not accompanied with fruiting body formation is induced simply by shifting the temperature of vegetatively growing cells from $32^{\circ}C$ to $15^{\circ}C$. Spores induced by socD500 mutation is not as thick as that of wild-type fruiting body. In socD500 genetic background, two of ten C-signal dependent genes, $\Omega$DK4506 and $\Omega$DK4406 are more highly expressed in growing cells at $15^{\circ}C$. These results indicate that the socD500 mutation may be partly involved in the regulation of expression of two C-signal dependent genes and genes for sporulation in this transduction pathway.

Effect of Factors on the Sporulation of Bacillus cereus and Their Thermal Resistance (여러 조건에 따른 Bacillus cereus 포자 형성과 포자의 열저항성 평가)

  • Kim, Seung-Ju;Jung, Jin-Ho;Tahk, Hong-Min;Baek, Seung-Youb;Lee, Sun-Young
    • Journal of Food Hygiene and Safety
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    • v.24 no.3
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    • pp.256-261
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    • 2009
  • Bacillus cereus is a gram-positive spore-forming bacterium and produces an emetic or diarrheal syndrome induced by an emetic toxin and an enterotoxin, respectively. In this study, the effect of different types of media, temperature, and time on the sporulation of B. cereus, and thermal resistance of B. cereus spores produced in various temperatures were evaluated. The highest levels of spores were detected when they are produced at $25^{\circ}C$. There were no significant differences in levels of spores produced at $25^{\circ}C$ among culture media and times while levels of spores produced at $43^{\circ}C$ were significantly reduced with the increase of time. However, thermal resistance of B. cereus spores could be affected by incubation temperature. In fact, higher D-values (12.0, 10.1, and 5.9 min for 2,4, and 6 weeks, respectively) of spores produced at $43^{\circ}C$ were observed than did in samples produced at other temperatures (25 and $37^{\circ}C$). D-values of spores were 7.7, 8.2, and 12.0 min when they were produced at 25,37, and $43^{\circ}C$ for 2 weeks, respectively. The sporulation of B. cereus at $25^{\circ}C$ could result in high amounts of spores however the sporulation at $43^{\circ}C$ for 2 weeks could be effective to produce thermal resistant spores.

Producton of Yeast Spores from Rice Wine Cake. (주박으로부터 효모포자의 생산)

  • Im, Yong-Sung;Bae, Sang-Myeon;Kim, Geun
    • Microbiology and Biotechnology Letters
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    • v.32 no.2
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    • pp.184-189
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    • 2004
  • Rice wine cake (RWC) is the solid waste obtained after rice wine fermentation. For the mass production of the spores of yeast Saccharomyces from RWC, the optimum pretreatment condition of RWC, the optimum composition of culture medium, and the optimum culture condition were examined. For sporulation, yeast cells were grown in the pre sporulation medium (PSM), transferred into sporulation medium (SM) containing 1 % potassium acetate, and incubated in a rotary shaking incubator at $25^{\circ}C$ for 4 days. The supernatant of the mixture of RWC and water was used as the presporulation medium (PSM). The optimum temperature and time for the pre-incubation of the mixture of RWC and water (1:2) to obtain maximum sporulation yield were $V^{\circ}C$ and 24 hr, respectively, and optimum culture time in PSM was 48 hr. Using these optimum conditions, the asci number obtained was 0.72$ 1.06${\times}$10^{8}$$m\ell$. The addition of wheat coat koji into SM increased the final number of asci to beTEX>$10^{8}$ $m\ell$. Spores were formed in the SM with the initial pH of 7-11, but no spores were formed in the SM with the initial pH of 5. To save the time and effort to pretreat the RWC, 2% and 0.5% RWC without any pretreatment were directly added into PSM containing 1 % brown sugar and SM, respectively, and the maximum asci number of $1.27${\times}$10^{8}$ /$m\ell$ was obtained.

HpkA, a Histidine Protein Kinase Homolog, is Required for Fruiting Body Development in Myxococcus xanthus

  • Park, Sooyeon;Kim, Jihoon;Lee, Bongsoo;Zusman, David R;Cho, Kyungyun
    • Journal of Microbiology and Biotechnology
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    • v.13 no.3
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    • pp.400-405
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    • 2003
  • A gene (hpkA), encoding a histidine protein kinase homolog, has been identified in the upstream region of the espAB operon in Myxococcus xanthus. It encodes a 333 amino acid (35,952 Da) protein with a histidine protein kinase domain in the region from amino acid 90 to 317. Null mutations in the hpkA gene caused formation of loose irregular fruiting bodies, while wild-type strains developed tight hemispherical fruiting bodies under developmental conditions. Sporulation of the hpkA mutant was delayed by at least 12 h compared to that of the wild-type. It appeared that the hpkA mutation increased the expression of the espAB operon by more than 2-fold compared with the wild-type under developmental conditions. Expression of the hpkA gene was low under vegetative conditions, but was highly induced under developmental conditions.

CONIDIAL PRODUCTION OF CERCOSPORA BETICOLA SACC. ON TOMATO JUICE AGAR (토마도즙 한천배양기상에서의 사탕무 갈반병 분성포자형성)

  • LA, Yong Joon
    • Journal of Plant Biology
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    • v.6 no.1
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    • pp.8-10
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    • 1963
  • LA, Yong Joon (Coll. of Agr., Seoul National Univ.) Condial production of Cercospora beticola Sacc. on tomato juice agar. Kor. Jour. Bot. VI (1):8-10, 1963. Agar media containing various amount of tomato juice were tested to determine the degree of conidial production of Cercospora beticola. Non-sporulating culture on potato dextrose agar readily sporulated on agar media containing various amout of tomato juice 48 hours after transfer. Considerably small amount of sporulation occurred on agar media containing 10% of tomato juice. Sporulation increased considerably on media containing more than 20% of tomato juice; the higher the proportion of tomato juice in a medium, the greater the number of spores produced.

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The changes in the activities of Cellulase and Xylanase of Aspergillus phoenicis during the life cycle (Aspergillus phoenicis의 生活史를 통한 Cellulase 및 Xylanase의 活性 변화)

  • Oh, Chan-Seok;Lee, Yung-Nok
    • Korean Journal of Microbiology
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    • v.22 no.2
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    • pp.91-96
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    • 1984
  • The changes in the activities of Cellulase and Xylanase of A. phoencis during the life cycle were surveyed by using synchronized culture technique. Avicelase activity of the fungus was reached at peak in the initial hyphal growth stage, but decreased gradually during the conidiophore formation, vesicle-phialide formation, and sporulation stages in decreasing order. CMCase, Salicinase, and Xylanase activities were raised very high in the initial hyphal growth stage, but decreased gradually in conidiophore formation and vesicle-phialide formation stages, and then increased, more or less, in the sporulation stage.

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