• Journal of Microbiology and Biotechnology
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• 제1권1호
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• pp.6-11
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• 1991

This study deals with investigation of the ethanol tolerance of yeast strains with respect to fatty acid composition and intracelluar ethanol concentration during alcohol fermentation. The cell viabilities and fermentation abilities of Saccharomyces cerevisiae and Kluyveromyces fragilis were improved by aeration and addition of unsaturated fatty acids into growth medium. Aeration decreases the accumulation of ethanol, while increases unsaturated fatty acid contents inside yeast cells. Thus it was found that oxygen and unsaturated fatty acids play decisive roles in the increase of ethanol tolerance of yeasts.

• Applied Biological Chemistry
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• 제36권1호
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• pp.38-44
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• 1993

1) OBT mutant는 Clostridium saccharoperbutylacetonicum ATCC 13564(N1-4주(株))로부터 UV light와 butanol tolerance에 의해 분리했다. 동 돌연변이주(株)는 16.46g/l(1.4배 증가)의 부타놀과 4.6g/l(1.5배 증가)의 아세톤을 생산하고 전체 용매는 21.47g/l를 생산했다. 이 결과는 n-butanol을 생산하는 clostridial bacteria에서 error-prone pathway를 통한 misrepair의 약한 효과가 UV light와 butanol tolerance에 의해서 극복되었다는 것을 제시했다. 2) glucose 발효에 비교해서 mannitol 발효에서 OBT mutant는 acetone과 acetic acid는 생산되지 않았다. 전체용매에 대한 n-butanol과 ethanol의 비는 각각 10.3%와 10.6%씩 증가되었고 전체적으로는20.9% 증가된 반면, acetone의 비는 21.2%가 감소되었다. 또한 전체 용매에 대한 n-butanol의 최대비는 94.8%까지 증가하였다. 이들 결과는 산화합물(acetone, acetic acid, butyric acid)이 환원화합물(n-butanol, ethanol)로 전환된 것을 의미했다. 따라서 mannitol은 부산물인 산화합물을 제거하는데 사용할 수 있다.

• KSBB Journal
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• 제14권4호
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• pp.389-395
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• 1999

Bifidobcterium spp. can provide human being with several beneficial physiological. Therefor, there has been a considerable interest in products Bifidobcterium spp. dietary supplements or as starter cultures for probiotic products that may assint in the improvement of health on the human. But indusrial applications have been limited because Bifidobcterium spp. are sensitive to acidic pH due to organic acid produced by themselves and various conditions. The objective of this study was to establish new method for improvement of Bifidobcterium viability by entrapment im calcium alginate beads. We have a plan to select the most suitable polymer through the comparison with acid tolerance oxygen tolerance and theological properties of polymer. Increase of the viable number of Bifidobcterium induced increasing acid tolerance and oxygen tolernce trough the development of entrapment technique. The 4%, 3030mm diameter) sodium alginate beads led to the best survivability under acid condition. Especially, addition of 6% mannitol, 6% glycerol or 6% sorbitol to the sodium alginate helped a beneficial effect on viability against acid, bile salt, hydrogen peroxide and cold strage. The number of viability of entrapeede cells by retreatment was 96 fold higher than non-entrapeed cells after 5 hours of storage under pH 3 acidic condition. These experimental data clearly demonstrate that a whole cell immobilization by entrapment in calcium alginate beads is an important survival mechanism enable to withstand environmental stresses as the acidic condition, hydrogen peroxide toxicity and frozen state.

• 한국토양비료학회지
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• 제24권2호
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• pp.144-151
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• 1991

수도품종(水稻品種)의 내냉성관련인자(耐冷性關聯因子)로서 생체막구성물질(生體膜構成物質)에 중요(重要)한 역할(役割)을 하는 인지질(燐脂質)의 지방산조성(脂肪酸組成)과 지방산(脂肪酸)의 불포화비율(不飽和比率)을 증가(增加)시킬 수 있는 경화처리(硬化處理)에 의한 지방산(脂肪酸)의 변화(變化)를 조사(調査)하여 포장(圃場)에서 조사(調査)된 내냉성정도(耐冷性程度)와 비교검토(比較檢討)한 결과(結果)는 다음과 같다. 1. 수도(水稻) 32품종(品種)에서 분리(分離)한 인지질(燐脂質)의 지방조성(脂肪組成)은 Pamitic, Linoleic 및 Linolenic acid가 주(主) 지방산(脂肪酸)이었고, Palmitoleic, Stearic 및 Oleic acid가 소량(少量) 함유(含有)되어 있었다. 2. 저온처리(低溫處理)($15^{\circ}C$, 3일간)한 묘(苗)에서 포화지방산(飽和脂肪酸)인 Pamitic acid의 함량(含量)은 감소하고, 불포화지방산(不飽和脂肪酸)인 Linoleic acid의 함량(含量)은 증가하였다. 3. 지방산(脂肪酸)의 불포화비율(不飽和比率)은 저온처리(低溫處理)를 하므로써 높아졌으며, 내냉성(耐冷性)이 강(强)한 품종(品種)에서 비율(比率)이 높고, 약(弱)한 품종(品種)에서 낮아 내냉성정도(耐冷性程度)와 일치(一致)하는 경향을 보였다. 4. 경화처리(硬化處理)에 의하여 인지질지방산조성(燐脂質脂肪酸組成)중 Pamitic acid는 감소하고, Linoleic acid의 함량(含量)은 증가하였다. 5. 경화처리(硬化處理)를 하므로써 지방산(脂肪酸)의 불포화비율(不飽和比率)은 대조구(對照區)에 비하여 18~24% 증가되었다.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.452-460
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• 2016

Acid stress can affect the viability of probiotics, especially Bifidobacterium. This study aimed to improve the acid tolerance of Bifidobacterium longum BBMN68 using adaptive evolution. The stress response, and genomic differences of the parental strain and the variant strain were compared by acid stress. The highest acid-resistant mutant strain (BBMN68m) was isolated from more than 100 asexual lines, which were adaptive to the acid stress for 10^th, 20^th, 30^th, 40^th, and 50^th repeats, respectively. The variant strain showed a significant increase in acid tolerance under conditions of pH 2.5 for 2 h (from 7.92 to 4.44 log CFU/ml) compared with the wild-type strain (WT, from 7.87 to 0 log CFU/ml). The surface of the variant strain was also smoother. Comparative whole-genome analysis showed that the galactosyl transferase D gene (cpsD, bbmn68_1012), a key gene involved in exopolysaccharide (EPS) synthesis, was altered by two nucleotides in the mutant, causing alteration in amino acids, pI (from 8.94 to 9.19), and predicted protein structure. Meanwhile, cpsD expression and EPS production were also reduced in the variant strain (p < 0.05) compared with WT, and the exogenous WT-EPS in the variant strain reduced its acid-resistant ability. These results suggested EPS was related to acid responses of BBMN68.

• 한국식품과학회지
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• 제32권2호
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• pp.431-438
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• 2000

Adipic acid에 대해 저항성을 갖도록 변이된 Leuconostoc paramesenteroides (ANaP100) 균주의 내산성 특성을 조사하기 위하여 수소이온 투과도, $H^+-ATPase$ 활성, $Mg^{++}$ 해리도, 원형질막의 지방산 조성을 지표로 삼아 야생균주(LPw)와 비교하였다. 수소이온 투과도의 경우 pH 5에서 $t_{1/2}$ 값이 LPw는 4.3분, ANaP100은 4.8분으로서 변이균주가 다소 내산성이 높았으며 $H^+-ATPase$ 활성은 maximal activity가 Leu. paramesenteroides는 모두 pH 6.0에서 가장 높았고 LPw는 0.59 unit/mg protein, 변이균주는 0.63 unit/mg protein으로서 ANaP100이 LPw보다 활성이 높았다. 세포막의 산 손상(acid damage)에 의한 $Mg^{++}$ 해리도에서도 pH 4.0에서 2시간 경과 후 LPw는 52.2%, ANaP100은 27.3%로서 LPw에 비해 약 1/2가량 $Mg^{++}$이 적게 유출되어 산에 의한 세포막의 손상이 적었다. 원형질막의 지방산 조성은 ANaP100가 $C_{18:1}$은 감소하고, $C_{19:0,\;cyclo}$는 증가하여 내산성이 증대되었으며 또한 adipic acid 첨가시에도 LPw에 비해 우수한 증식을 보였다. 따라서 ANaP100이 LPw에 비해 내산성이 증가되었으며 adipic acid 저항성도 함유하는 것이 확인되었다.

• Journal of Microbiology
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• 제33권4호
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• pp.322-327
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• 1995

Tolerance of Mycobacterium sp. against organic solvents has been induced for the cholesterol side chain degradation by adding chemicals associated with synthesis of fatty acids or alcohols. Biotin of 300 .mu.g/1 and 0.5% aqueous ethanol solution were optima for the enhancement of ethanol tolerance of the microorganism. The induction of ethanol tolerance by biotin was found to be due to increase of degree of unsaturation of the fatty acids in membranous phospholipid of the cell, especially due to increase of oleic acid content. However when 0.5% of ethanol was added for the ethanol tolerance induction, there was an ambiguous correlation between ethanol tolerance and degree of unsaturation of the fatty acids, in spite of the fact that the induction increased the content of unsaturated fatty acids. Addition of 0.5% of ethanol induced several ethanol shock proteins having molecular weight similar to that of heat shock proteins.

• 대한수의학회지
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• 제40권4호
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• pp.701-706
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• 2000

This study was carried out to select the lactic acid bacteria(Lactobacillus, Streptococcus and Bifidobacterium) and yeast for probiotic use in pigs. Acid-tolerant 536 strains were isolated from the feces of 30 pigs. To select useful strains, the first screened strains were treated with strong acid solution(pH 2.5 to 3.0) for 3 hours and subsequentely treated with the anaerobic diluent solution containing 0.15% Oxgall for 3 hours. Among these strains, 151 strains showed strong tolerance to both acid and bile. Lactobacillus and Streptococcus tolerant to the acid and bile were treated with heat at $80^{\circ}C$ for 15 min, and at $70^{\circ}C$ for 5 min in Bifidobacterium and yeast. As a result of heat treatment, 38 strains were obtained as heat-tolerant strains. All of heat-tolerant strains were tested for antibiotic resistance against virginiamycin, sulfathiazole, aureomycin, neomycin, linsmycin, tiamulin and ASP250 which were used as feed additives for growth promotion in pigs. Finally, one strain each from Lactobacillus, Streptococcus, Bifidobacterium and yeast that showed resistance to acid, bile, heat and antibiotics was selected for probiotic use in pigs.

• 식물조직배양학회지
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• 제27권4호
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• pp.339-343
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• 2000

When plants are exposed to subfreezing temperatures ice crystals are forming within extracelluar space in leaves. The growth of ice crystal is closely related to the degree of freezing injury. It was shown that an antifreeze protein binds to an ice nucleator through hydrogen bonds to prevent growth of ice crystal and also reduces freezing damage. The antifreeze proteins in plants are similar to PR proteins but only the PR proteins induced upon cold acclimation were shown to have dual functions in antifreezing as well as antifungal activities. Three of the genes encoded for CLP, GLP, and TLP were isolated from barley and Kentucky bluegrass based on amino acid sequence revealed after purification and low temperature-inducibility as shown in analysis of the protein. The deduced amino acid of the genes cloned showed a signal for secretion into extracellular space where the antifreezing activity sup-posed to work. The western analysis using the antisera raised against the antifreeze proteins showed a positive correlation between the amount of the protein and the level of freeze tolerance among different cultivars of barely. Besides it was revealed that TLP is responsible for a freeze tolerance induced by a treatment of trinexapac ethyl in Kentucky bluegrass. Analysis of an overwintering wild rice, Oryza rufipogon also showed that an acquisition of freeze tolerance relied on accumulation of the protein similar to CLP. The more direct evidence for the role of CLP in freeze tolerance was made with the analysis of the transgenic tobacco showing extracellular accumulation of CLP and enhanced freeze tolerance measured by amount of ion leakage and rate of photosynthetic electron transport upon freezing. These antifreeze proteins genes will be good candidates for transformation into crops such as lettuce and strawberry to develop into the new crops capable of freeze-storage and such as rose and grape to enhance a freeze tolerance for a safe survival during winter.

• Journal of Microbiology and Biotechnology
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• 제20권7호
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• pp.1156-1162
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• 2010

During ethanol fermentation, bacterial strains may encounter various stresses, such as ethanol and acid shock, which adversely affect cell viability and the production of ethanol. Therefore, ethanologenic strains that tolerate abiotic stresses are highly desirable. Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation, ultraviolet light, and desiccation, and therefore constitute an important pool of extreme resistance genes. The irrE gene encodes a general switch responsible for the extreme radioresistance of D. radiodurans. Here, we present evidence that IrrE, acting as a global regulator, confers high stress tolerance to a Zymomonas mobilis strain. Expression of the gene protected Z. mobilis cells against ethanol, acid, osmotic, and thermal shocks. It also markedly improved cell viability, the expression levels and enzyme activities of pyruvate decarboxylase and alcohol dehydrogenase, and the production of ethanol under both ethanol and acid stresses. These data suggest that irrE is a potentially promising gene for improving the abiotic stress tolerance of ethanologenic bacterial strains.