• 미생물학회지
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• 제52권2호
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• pp.220-225
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• 2016

쌀 전분을 원료로 효모를 직접 이용하여 항산화제 glutathione(GSH)이 풍부한 알코올 음료를 제조할 목적으로 GSH 함량과 당화능을 증진시키기 위하여 Saccharomyces cerevisiae의 ${\gamma}$-glutamylcysteine synthetase 유전자(GSH1), Debaryomyces occidentalis의 glucoamylase 유전자(GAM1), 그리고 ${\alpha}$-amylase 유전자(AMY)를 청주 효모 S. cerevisiae에서 공동 발현시켰다. 재조합 청주 효모의 세포외 GSH 함량은 원균주에 비해 1.5배 증가하였다. 2% (w/v) 쌀 전분이 함유된 배지에서 배양하였을 때 GAM1과 AMY 유전자 모두 발현하는 효모 균주의 glucoamylase에 의한 당화능은 GAM1유전자만 발현하는 균주와 비교하여 2배 증가하였다. 이 새로운 균주는 쌀 전분이 20%(w/v) 함유된 배지에서 7일간 발효를 통해 에탄올 11% (v/v)를 생산하였고, 전분 함유량의 90% 이상을 소비하였다.

• Mycobiology
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• 제32권1호
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• pp.11-16
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• 2004

Winter mushroom, Flammulina velutipes, needs low temperature during its cultivation. To save on farm costs, especially during summer, a strain adaptable to a higher or elevated-temperature must be developed. At the start of breeding program, parental strains which could endure high temperature were obtained. Seuenty four dikaryotic strains were collected and divided into four groups according to the nature of temperature. They also had different fruiting temperature. Finally we selected three brown strains ASI 4048, 4057 and 4072, and collected their spores. These selected strains can germinate even at a high temperature of $32^{\circ}C$, which were dramatically higher than the other strains. Based on these results, the new white strain adapted to mid-temperature by backcross mating was developed. Molecular markers were applied to select white fruitbody producing strains without cultivation. They showed a specific band which co-segregated with brown fruitbody forming strains in $BC_1F_1$ progenies. Selected white strains were tested under several elevated temperature conditions.

• 미생물학회지
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• 제4권1호
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• pp.1-13
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• 1966

The author examined for observing the structures of pyrenoid and cell wall of three strains of Chlorella ellipsoidea and relation of pyrenoid to starch grain formation at the ultrastructure level. 1. The development of pyrenoid of Chlorella species from the time of its initiation and its subdetail sequent activities are described in some pictures. 2. Close correlation between the findings of light microscopy and electron microscopy is proved. 3. The pyrenoid is a dynamic organellae which continues to change its appearance thoughout the development of the Chlorella cell. 4. The starch grains are continously formed by deposition of carbohydrate within the chloroplast with the aid of pyrenoid factors. 5. Some parental starch grains are passed on the daughter cell during cell division. 6. The Da stage cells contain only chlaroplast without pyrenoid matrix. In Da stage a pyrenoid is surrounded by starch and starch grains appear in chloroplast lamellae. In $L_1L_2$ stages, large starch grains of lens form accumulate in cell. In $L_3$ stage pyrenoid disappears for a time and starch grains are scattered. In cell division stage starch grains are divided into four groups. In $L_4$ stage, pyrenoid substance appears temporarily and disappears soon. At this stage the cell is constituted of Dn cell containing chloroplast only. 7. The cellular boundary of JE strain except Y 815 and Y 511 strain contains 250.angs. intermediate layer of unknown chemical composition between the fibrillar cellulose wall and the out capsule layer.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1127-1134
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• 2009

Escherichia coli excretes acetate during aerobic growth on glycolytic carbon sources, which has been explained as an overflow metabolism when the carbon flux into the cell exceeds the capacity of central metabolic pathways. Nonacetogenic growth of E. coli on gluconeogenic carbon sources like succinate or in carbon-limited slow growth conditions is believed an evidence for the explanation. However, we found that a strain defected in the acs (acetyl Co-A synthetase) gene, the product of which is involved in scavenging acetate, accumulated acetate even in succinate medium and in carbon-limited low growth rate condition, where as its isogenic parental strain did not. The acs promoter was inducible in noncatabolite repression condition, whereas the expression of the ackA-pta operon encoding acetate kinase and phosphotransacetylase for acetate synthesis was constitutive. Results in this study suggest that E. coli excretes and scavenges acetate simultaneously in the carbon-limited low growth condition and in nonacetogenic carbon source, and the activity of the acetate consumption pathway directly affects the accumulation level of acetate in the culture broth.

• 한국미생물·생명공학회지
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• 제14권5호
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• pp.365-369
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• 1986

새로운 alcohol발효성 효모 균주 개발을 목적으로 S. diastaticus 와 C. tropicalis간의 세포 융합을 하여 얻은 fusant의 성질에 대해서는 제3보$^{(10)}$에서 발표한 바이다. 본 보에서 는 fusant의 glucoamylase와 pullulanase activity와 glucoamylase의 성질 및 발효력을 조사하였다. glucoamylase activity는 parent보다 fusant가 1.5배 높은 활성을 나타내었고 pullulanase activity 역시 두배의 높은 활성을 나타내었다. glucoamylase의 성질을 조사한 바 온도, pH에서 비슷한 경향을 나타내었으며 발효력을 조사하기 위하여 정치법에서는 기질을 soluble starch로 한 것 보다 liquefied potato starch에서 alcohol 생성력이 2배 증가되었으며 발효력 또한 더 나았다. 15% 액화한 potato starch를 기질로하여 jar-fermenter에서 발효시켰을 때 당화율 94%에서 생성된 alcohol이 7.8% (v/v)이고 소비된 당에 대한 발효율은 78%였다.

• Journal of Microbiology and Biotechnology
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• 제23권11호
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• pp.1529-1535
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• 2013

Tuberculosis is a worldwide epidemic disease caused by Mycobacterium tuberculosis, with an estimated one-third of the human population currently affected. Treatment of this disease with aminoglycoside antibiotics has become less effective owing to antibiotic resistance. Recent determination of the crystal structure of the M. tuberculosis Rv3168 protein suggests a structure similar to that of Enterococcus faecalis APH(3')-IIIa, and that this protein may be an aminoglycoside phosphotransferase. To determine whether Rv3168 confers antibiotic resistance against kanamycin, we performed dose-response antibiotic resistance experiments using kanamycin. Expression of the Rv3168 protein in Escherichia coli conferred antibiotic resistance against $100{\mu}M$ kanamycin, a concentration that effected cell growth arrest in the parental E. coli strain and an E. coli strain expressing the $Rv3168^{D249A}$ mutant, in which the catalytic Asp249 residue was mutated to alanine. Furthermore, we detected phosphotransferase activity of Rv3168 against kanamycin as a substrate. Moreover, docking simulation of kanamycin into the Rv3168 structure suggests that kanamycin fits well into the substrate binding pocket of the protein, and that the phosphorylation-hydroxyl-group of kanamycin was located at a position similar to that in E. faecalis APH(3')-IIIa. On the basis of these results, we suggest that the Rv3168 mediates kanamycin resistance in M. tuberculosis, likely through phosphotransferase targeting of kanamycin.

• 동아시아식생활학회지
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• 제5권1호
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• pp.93-99
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• 1995

For the improvement of the L-lysine productivity of Brevibacterium flavum and Corynebacterium glutamicum, fusants were induced by interspecific protoplast fusion of Bacillus subtilis with C. glutamicum and B. flavum. The following results were obtained through protoplast formation of strains condition of protoplast fusion, characteristics of the fusants, and the productivity of lysine form starch. B. flavum BF-5 and C. glutamicum protoplasts were made by the treatment of 0.3unit/$m\ell$ of penicillin G at the early stationary growth phase for 2 hours followed by incubation with 10mg/$m\ell$ of lysozyme at 37$^{\circ}C$ for 120 min. When a mixture of the protoplast was treated with 30% PEG(M.W.6,000) solution containing 50mM CaCl2 at optimal conditions, the intergeneric fusion frequency between protoplasts of C. glutamicum CG-2 and B. subtilis BD 224 was 7.1${\times}$105. The genetic properties on the L-lysine producing fusants were compared with those of parental strains. As a results, the intergeneric fusants were completed in each auxotrophic requirement, resistances for S-(2-amino-ethyl)-L-cysteine and kanamycine were confirmed. And one of fusants selected, FBB-41 were found to be genetically stable fusants. The aspartokinase activity of FBB-41 strain increased than that of the parent strain.

• 한국버섯학회지
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• 제16권3호
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• pp.140-146
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• 2018

Pleurotus eryngii is one of the most commercially important mushrooms cultivated in Korea. However, the shelf-life of the fruiting body is short, limiting its export. A new hybrid strain H17 of P. eryngii was developed to extend the shelf-life by mono-mono crossing between monokaryotic strains derived from DanBi and KNR2774. Although the cultivation period of H17 was slightly longer than that of the reference cultivar Kenneutari No.2, the quality did not change and remained normal after a period of 65.0 days at $4^{\circ}C$. This result was significantly different from that of the reference cultivar Kenneutari No.2. Analysis of the genetic characteristics of the new hybrid strain H17 revealed a different profile from that of the parental and reference cultivars when random amplification of polymorphic DNA (RAPD) primers was used. These results demonstrate that H17 is a new cultivar with improved storability after harvesting.

• 한국식물병리학회지
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• 제14권6호
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• pp.606-611
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• 1998

An antagonistic bacterium, Pseudomonas flurorescens MC07 inhibited the mycelial growth of Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici in on potato dextrose agan (PDA) and other media. The strain MC07 conlonizes various plant roots and possesses antifungal activity. To determine the role of antifungal activity of the bacterium in disease suppression, a mutant Okm3-4 which lost its activity was isolated after screening 2,500 colonies generated by Omegon-Km insertions. The mutant Okm3-4 showed diminished growth inhibition of R. solani, P. ultimum, F. oxysporum, and Ph. capsici in vitro and had reduced suppressive effects on sesame damping.-off compared to the parental strain. In soils, accumulation of the pathogens by continuous cropping, 90% of sesame plants were killed by natural infection of damping-off whereas, only 29% of plants grown from seeds treated with MC07 were killed. On the other hand, 85% of plants died when sesame seeds were treated with the Okm3-4 cells. This indicated that antifungal activity of MC07 in vitro is directly responsible for the suppression of damping-off disease. Emergence rates of sesame seeds in pots containing diseased soil were 33%. However, MC07 treatments on seeds significantly improved emergence rates, which has similar effects of Benomyl treatment. The mutant Okm3-4 exhibited 53% of emergence rate. This indicated that antifungal activity of MC07 also affects the emergence rate of sesame seeds.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.789-796
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• 2000

In order to analyze the effects of tktA, $aroF^{FBR}$, and aroL expression in a tryptophan-producing Escherichia coli, a series of plasmids carrying the genes were constructed. Introduction of tktA, $aroF^{FBR}$, and aroL into the E. coli strain resulted in approximately 10-20 fold increase in the activities of transketolase, the feedback inhibition-resistant 3-deoxy-D-arabinoheptulsonate-7-phosphate synthase, and shikimate kinase. Expression of $aroF^{FBR}$ in the aroB mutant strain of E. coli resulted in the accumulation of 10 mM of 3-deoxy-D-arabinoheptulsonate-7-phosphate (DAHP) in the medium. Simultaneous expression of tktA and $aroF^{FBR}$ in the strain further increased the amount of excreted DAHP to 20 mM. In contrast, the mutant strain which has no gene introduced accumulated 0.5 mM of DAHP. However, the expression of tktA and $aroF^{FBR}$ in a tryptophan-producing E. coli strain did not lead to the increased production of tryptophan, but instead, a significant amount of shikimate, which is an intermediate in the tryptophan biosynthetic pathway, was excreted to the growth medium. Despite the fact that additional expression of shikimate kinase in the strain could possibly remove 90% of excreted shikimate to 0.1 mM, the amount of tryptophan produced was still unchanged. Removing shikimate using a cloned aroL gene caused the excretion of glutamate, which suggests disturbed central carbon metabolism. However, when cultivated in a complex medium, the strain expressing tktA, $aroF^{FBR}$, and aroL produced more tryptophan than the parental strain. These data indicate that additional rate-limiting steps are present in the tryptophan biosynthetic pathway, and the carbon flow to the terminal pathway is strictly regulated. Expressing tktA in E. coli cells appeared to impose a great metabolic burden to the cells as evidenced by retarded cell growth in the defined medium. Recombinant E. coli strains harboring plasmids which carry the tktA gene showed a tendency to segregate their plasmids almost completely within 24h.