• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.81-84
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• 2000

• KSBB Journal
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• 제5권2호
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• pp.125-131
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• 1990

본 연구에서는 인공감미료 aspartamed의 원료인, I-phenylalanine을 생산하는 tyrosine auxotroph이며 다수의 아미노산 유도체의 저항성이 있는 변이주 Corynebact-erium glutamicum ATCC21674배양의 동특성을 조사하였다. 이 균주는 tyrosine이 존재하지 않아도 성장하고 또한 과량의 tyrosine을 함께 생성하는 것으로 보아 autotrophic mutant가 reversion된 revertant로 추정된다. 대수증식기에서의 비증식속도는 $0.087hr^-1$이었다. Phen-ylalanine 최대생성속도는 세포증식이 끝날 때에 얻어졌으며 세포량의 증가는 이산화탄소의 생산량의 증가와 비례함을 알 수 있었다. 이산화탄소 생성속도는 당소비속도와도 비례하므로 이를 이용하여 발효상태를 알 수 있는 유용성이 확인되었다.

• 미생물학회지
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• 제13권2호
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• pp.51-58
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• 1975

S.typhimurium LT-2의 histidine auxotroph를 이용한 돌연변이 유발물질 검출방법으로 PA 및 NPA의 돌연변이 유발능을 실험했다. PA는 microsomal enzyme에 의해 강한 돌연변이 유발효과를 나타냈으며 NPA는 직접 처리했을 때 강한 돌연변이 유발효과를 나타냇고 microsomal enzyme에 의한 활성화로는 그 비율이 증가되지 않았다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제1권1호
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• pp.41-45
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• 1996

Effects of yeast extract and ammonium sulfate were investigated on the production of L-or-nithine by an arginine auxotroph, Brevibacterium ketoglutamicum in flask and batch cultures. Yeast extract as an arginine source and ammonium sulfate as an inorganic nitrogen source had significant effects on L-ornithine production and cell growth. L-ornithine production was repressed by the excessive addition of arginine. Reversion of auxotrophic cells to the wild type was observed when the initial yeast extract concenfration was too low. There existed optimum concentrations of yeast extract and ammonium sulfate for L-or-nithine production. The effects of yeast extract and ammonium sulfate concentrations of the Leudeking-Piret model parameters were examined to analyze the relationship between cell growth and L-ornithine production.

• Archives of Pharmacal Research
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• 제20권5호
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• pp.448-453
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• 1997

Protoplast fusion between isoleucine-, argihine- and thymidine-requiring auxotroph $(Ile^{-}, Arg^{-}, Thy^{-})$ of Lentinula edodes and arginine-requiring auxotroph $(Arg^-)$ of Coriolus versicolor has been achieved using 30% polyethylene glycol (M.W.4000) in 10 mM $CaCl_2$-glycine solution (pH 8.0). Fusion hybrids were selected in the 0.6 M sucrose supplemented minimal media on the basis of nutritional complementation with fusion frequency of $7.4{\times}10{-6}$ The hybrids included both parental and non-parental types in colony morphology, growth rate and isozyme patterns. We succeeded inter-order protoplast fusion between the auxotrophs of Lentinula edodes and Coriolus versicolor overcoming the natural barriers of incompatibility. We examined the characteristics of the hybrids and clarified the fusion rocess using electron microscopy.

• 한국미생물·생명공학회지
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• 제27권4호
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• pp.292-297
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• 1999

Overproduction of L-ornithine by mutant strains isolated from Brevibacterium detoglutamicum BK1046 was investigated. The strain was a L-ornithine auxotroph and exhibited culture instability during fermentation. Through a sequential screening effort, a highly stable strain with lless revertant formation was finally selected and designated B. ketoglutamicum BK52 (KCTC0141BP). It prouduced L-ornithine at a high concentration (above 9 g/L) independent of subculture or cultivation time, and also had a very low tendency of revertant formation. In a long-term storage, this strain maintained its cell stability and productivity of L-ornithine to a reasonable range.

• Journal of Microbiology and Biotechnology
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• 제4권2호
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• pp.95-101
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• 1994

The effects of glycine on cell growth and L-omithine production were investigated in shake-flask and jar fermentor cultures of a citrulline auxotrophic mutant, Brevibacterium ketoglutamicum BK 1046. In the shake-flask culture, the optimal concentration of glycine for L-ornithine production was found to be 20 g/l. In the jar fermentor culture with the glycine at an initial concentration of 20 g/l, L-ornithine production increased by 28%, compared to that of the culture with no glycine added. 37 g/l of L-ornithine was produced when additional feeding of glycine (5 g/l) was made. This was a significant improvement in L-ornithine production compared to that (ca. 24 g/l) of the corresponding batch culture conducted without glycine. According to the stoichiometric analysis with the batch fermentation results, the experimental and theoretical L-ornithine yields based on the glucose consumption were 0.24 and 0.59, respectively. This indicates that the performance of L-ornithine fermentation can further be improved by the supplementation of glycine and the development of a mutant strain possessing a higher growth yield.

• 한국균학회지
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• 제21권3호
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• pp.230-234
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• 1993

R. nigricans Ehrenberg의 돌연변이주를 분리하기 위하여 화학적인 돌연변이원인 N-Methyl-N'-Nitro-N-Nitrosoguanidine(MNNG)과 Ethyl Methane Sulphonate(EMS)의 최적 처리 조건을 조사하였을 때, MNNG농도는 $125{\mu}g/ml$, 처리시간이 60분일 때 돌연변이율이 가장 높은 생존율 0.1-1.0%를 나타내었다. MNNG를 이용하여 영양요구성 돌연변이주 Leucine auxotroph를 분리하였으며, 포자낭병의 길이가 축소된 것, 포자낭병의 모양이 나선형으로 변한 것, 그리고 포자낭과 포자낭포자의 크기가 감소된 것 등 세 가지 형태적 변이주를 분리하였다.

• 미생물과산업
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• 제19권2호
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• pp.34-41
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• 1993

Industrial strain improvement is concerned with developing or modifying microorganisms used in production of commercially important fermentation products. The aim is to reduce the production cost by improving productivity of a strain and manipulating specific characteristics such as the ability to utilize cheaper raw materials or resist bacteriophages. The traditional empirical approach to strain improvement is mutation combined with selection and breeding techniques. It is still used by us to improve the productivity of organisms in amino acids, organic acids and enzymes production. The breeding of high L-lysine-producing strain Au112 is one of the outstanding examples of this approach. It is a homoserine auxotroph with AEC, TA double metabolic analogue resistant markers. The yield reaches 100 g/l. Besides, the citric acid-producing organism Aspergillus niger, Co827, its productivity reaches the advanced level in the world, is also the result of a series mutations especially with $^60Co{\gamma}$-radiation. The thermostable .alpha.-amylase producing strain A 4041 is the third example. By combining physical and chemical mutations, the strain A 4041 becomes an asporogenous, catabolite derepressed mutant with rifamycin resistant and methionine, arginine auxotroph markers. The .alpha.-amylase activity reaches 200 units/ml. The fourth successful example of mutation in strain improvement is the glucoamylase-producing strain Aspergillus niger SP56, its enzyme activity is 20,000 units/ml, 4 times of that of the parental strain UV-11. Recently, recombinant DNA approach provides a worthwhile alternative strategy to industrial strain improvement. This technique had been used by us to increase the thermostable .alpha.-amylase production and on some genetic researches.

• Applied Biological Chemistry
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• 제28권1호
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• pp.13-18
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• 1985

세균의 protopalst 융합을 연구하기 위하여 Bacillus subtilis로부터 두 개의 영양 요구성 균주를 NTG처리에 의해서 분리하였다. 두 개의 영양 요구성 균주는 Uracil 요구성 균주와 Tryptophan 요구성 균주였다. $ura^-$균주와 $trp^-$균주의 친주로의 역돌연변이율은 각각 $2.4{\times}10^{-8}$과 $1{\times}10^{-8}$이하였다. Lysozyme 처리에 의하여 protoplast를 만들기 위한 최적 pH와 온도는 6.5와 $30^{\circ}C$였다. Protoplast 생성을 위한 lysozyme의 최적농도는 $200{\mu}g/ml$였다. Protoplast가 본래의 균체로 회복되는 율은 3.3%였다.