• 한국미생물·생명공학회지
• /
• 제44권4호
• /
• pp.488-492
• /
• 2016

S. fibuligera 균주는 생전분을 분해하는 활성이 있는 효모 균주이다. 본 연구에서는 첨가되는 젖산의 농도가 점차 증가하는 장기간 반복 회분식 배양 방법을 사용하는 적응진화를 통하여 S. fibuligera 균주의 젖산에 대한 내성을 증진시키고자 하였다. 진화된 균주인 S. fibuligera MBY1940 균주는 비성장속도 측정과 평판배지를 사용하는 성장분석을 통하여 모균주가 성장할 수 없는 젖산 농도 2.5%에 대해서도 내성을 나타내는 것을 확인하였다. 전자현미경 관찰을 통하여 젖산이 첨가된 스트레스 조건에서 모균주는 신장된 세포 형태와 세포막에 손상을 입은 것으로 보아 진화된 균주에 비해 젖산에 대하여 상대적으로 취약한 것으로 판단되었다.

• Journal of Plant Biotechnology
• /
• 제4권2호
• /
• pp.53-58
• /
• 2002

Adverse environmental conditions such as drought, high salt and cold/freezing are major factors that reduces crop productivity worldwide. According to a survey, 50-80% of the maximum potential yield is lost by these "environmental or abiotic stresses", which is approximately ten times higher than the loss by biotic stresses. Thus, improving stress-tolerance of crop plants is an important way to improve agricultural productivity, In order to develop such stress-tolerant crop plants, we set out to identify key stress signaling components that can be used to develop commercially viable crop varieties with enhanced stress tolerance. Our primary focus so far has been on the identification of transcription factors that regulate stress responsive gene expression, especially those involved in ABA-mediated stress response. Be sessile, plants have the unique capability to adapt themselves to the abiotic stresses. This adaptive capability is largely dependent on the plant hormone abscisic acid (ABA), whose level increases under various stress conditions, triggering adaptive response. Central to the response is ABA-regulated gene expression, which ultimately leads to physiological changes at the whole plant level. Thus, once identified, it would be possible to enhance stress tolerance of crop plants by manipulating the expression of the factors that mediate ABA-dependent stress response. Here, we present our work on the isolation and functional characterization of the transcription factors.n factors.

• 한국식품과학회지
• /
• 제33권5호
• /
• pp.574-581
• /
• 2001

감식초로부터 초산 생성능이 우수한 Acetobacter sp. S-1, S-2 및 S-3를 분리 동정하고 그 미생물학적 특성과 내산성을 평가하였다. 분리 균들은 모두 Gram 음성의 단간균으로 포자를 형성하지 않았고 운동성이 있었으며, catalase, methyl red, oxidation fermentation, Voges-Proskaues 및 nitrate reduction 시험에서 양성반응을 나타내었고 hydrogen sulfide와 ONPG 시험에서는 음성반응을 나타내었다. 분리균들은 Carr 배지내에서 표준 균주인 Acetobacter aceti, Acetobacter liquefaciens, Acetobacter diazotrophicus와 큰 차이 없이 정상적인 생육곡선을 나타내었으며, 산 생성의 경향도 비슷하였다. 배양최적온도는 $30^{\circ}C$이었으며 최적 초기에탄올 농도는 6%이었다. 분리된 Acetobacter sp. 균주들은 4% 이상의 초산 농도에서 그 생육과 산 생성이 억제되었다. 초산의 농도가 증가할수록 Acetobacter sp. 세포내의 $Mg^{++}$누출량이 증가하여 6% 초산농도에서는 거의 대부분의 $Mg^{++}$이 누출되었다. 분리균들의 glycolysis 능력은 알칼리에서보다 산성 쪽에서 더 안정적이었으며 최적 pH는 $6.0{\sim}7.0$이었다. Acetobacter sp. S-1과 S-3의 $H^+-ATPase$의 최적 pH는 $5.5{\sim}7.5$이었고 Acetobacter sp. S-2는 pH $6.0{\sim}7.5$이었다.

• Journal of Microbiology and Biotechnology
• /
• 제26권7호
• /
• pp.1190-1197
• /
• 2016

The acid response of Bifidobacterium longum subsp. longum BBMN68 has been studied in our previous study. The fab gene, which is supposed to be involved in membrane fatty acid biosynthesis, was demonstrated to be induced in acid response. In order to investigate the relationship between acid response and cell membrane fatty acid composition, the acid adaptation of BBMN68 was assessed and the membrane fatty acid composition at different adaptation conditions was identified. Indeed, the fatty acid composition was influenced by acid adaptation. Our results showed that the effective acid adaptations were accompanied with decrease in the unsaturated to saturated fatty acids ratio (UFA/SFA) and increase in cyclopropane fatty acid (CFA) content, which corresponded to previous studies. Moreover, both effective and non-effective acid adaptation conditions resulted in decrease in the C_18:1 cis-9/C_18:1 trans-9 ratio, indicating that the C_18:1 cis-9/C_18:1 trans-9 ratio is associated with acid tolerance response but not with acid adaptation response. Taken together, this study indicated that the UFA/SFA and CFA content of BBMN68 were involved in acid adaptation and the C_18:1 cis-9/C_18:1 trans-9 ratio was involved in acid tolerance response.

• Journal of Pharmaceutical Investigation
• /
• 제30권1호
• /
• pp.47-50
• /
• 2000

A new technique has been developed for the preparation of Lactobacillus microcapsules to enhance the stability against high temperature, humidity, gastric acid and bile acid. Employing fluidized bed coating, primary sub-coating was processed in non-organic solvent system, so that Lactobacillus did not directly contact with organic solvent. Secondary enteric-coating was processed in organic solvent with low temperature $(below\;33^{\circ}C)$ technique, which minimized the heat labilability of Lactobacillus. Survival rate of Lactobacillus within microcapsule was not less than 95% and acid tolerance was above 30% in the artificial gastric acid. Further more it was dissolved in the artificial intestine juice within 2-3 hr. Average size of Lactobacillus microcapsules was $450\;{\mu}m$(25-50 mesh) and its viability was above 90% in the direct tableting.

• KSBB Journal
• /
• 제30권1호
• /
• pp.33-37
• /
• 2015

Recently, several health benefits of rice wine, makgeolli, were known due to the interest on the traditional Korean liquor and the researches on the rice wine are increasing. Organic acids produced during the process of rice wine fermentation play important roles in the taste and flavor. In this study, we have examined the optimal conditions for lactic acid production in rice koji as a carbon source. Skim milk was also used as a supplementary ingredient for the optimization of lactic acid fermentation. Bacterial growth of Lactobacillus sakei was monitored under this condition. The pH, acidity of the culture and the ethanol tolerance of this bacterium were also tested. Through these experiments, we were able to optimize the growth condition of lactic acid bacteria by the addition of skim milk. This was also able to affect the change of pH, acidity, sugar concentration and alcohol tolerance, which might contribute to the improvement of the quality of rice wine. The optimal condition for the growth was 2 days with 10% (w/v) of skim milk concentration. With these results, it was confirmed that rice koji was an effective carbon source for the growth of lactic acid bacteria.

• KSBB Journal
• /
• 제20권2호
• /
• pp.76-83
• /
• 2005

Lactic acid bacteria were isolated from pig feces for probiotics. The six isolated strains were identified as Lactobacillus paracasei (Lp), Lactobacillus fermentum (Lf), Lactobacillus brevis (Lb), Lactobacillus plantarum (P1 , P2), and Pediococcus pentosaceus (P3) by its sugar utilization, morphological and physiological characteristics. Pl was showed largest antibacterial inhibition zone among the isolated strains. It was against Salmonella gallinarum 25mm, E. coli 20.5mm, Staphylococcus aures 24mm, and Pseudomonas aeruginosa 28mm by inhibitory zone, respectively. Lf was showed hyper acid tolerance, $80\%$ survival rate for 40 minutes, and P1, Lb showed hyper bile tolerance, $408\%,\;283\%$ survival rate for 9 hrs, respectively. Therefore the Lf, P1, and P2 strains were expected to probiotics.

• Entomological Research
• /
• 제48권6호
• /
• pp.514-521
• /
• 2018

Drosophila melanogaster Meigen and Drosophila suzukii Matsumura are taxonomically close Drosophila species belonging to the family Drosophilidae and melanogaster group. D. melanogaster is thought to be evolutionarily adapted to overripe, decaying, and fermented fruits, in which large amounts of chemicals such as ethanol, acetic acid, and 2-phenylethanol are produced, whereas, D. suzukii is attracted to fresh ripening fruit. Considering the distinct habitats of the two flies, D. suzukii is hypothesized to exhibit higher susceptibility to these chemicals than D. melanogaster. Therefore, in this study, we investigated the survival rate of the flies at various concentrations of three chemicals (2-phenlyethanol, acetic acid, and ethanol) and calculated the lethal concentration (LC) values to compare the tolerance and susceptibility of D. melanogaster and D. suzukii to the chemicals. Our results revealed that D. melanogaster exhibited higher tolerance than D. suzukii to all chemicals, supporting the hypothesis of different evolutionary adaptations to distinct habitats of the two flies.

• 한국미생물·생명공학회지
• /
• 제44권2호
• /
• pp.201-207
• /
• 2016

건강한 닭의 맹장에서 분리한 Lactobacillus sakei LAB 2와 LAB 8의 생균제로 이용을 알아보기 위해 기본적인 특성과 면역활성을 시험하였다. LAB 2와 LAB 8은 높은 내산성과 내담즙성을 가지고 있으며, 1차 대사산물인 유기산에 기인한 항균활성을 보였다. Salmonella 종을 병원성균으로 이용하여 최대 항균력을 나타내는 시간을 시험한 결과 48시간으로 나타났으며, 생성된 유기산 중 젖산의 생산량은 다른 Lactobacillus 균주보다 높게 조사되었다. In vitro 모델로 알아본 면역증진효과는 면역관련 세포의 증식과 사이토카인의 생산량 증가로 확인하였다. 이에 Lactobacillus sakei LAB 2와 LAB 8은 유용한 생균제로 개발할 수 있는 균으로 생각된다.

• Journal of Dairy Science and Biotechnology
• /
• 제35권4호
• /
• pp.249-254
• /
• 2017

The purpose of this study was to investigate the acid tolerance, bile acid tolerance, and fermentation activity of lactic acid bacteria isolated from Kimchi in the presence of hydrolysates of whey protein concentrate. Kimchi isolates DK109, DK119, DK121, DK128, DK211, DK212, and DK215, which were identified as Lactobacillus sp., and L. casei DK128 showed the highest acid and bile acid tolerance. To produce whey hydrolysates, enzymes were added to a 10% (w/v) whey protein concentrate (WPC) solution at 1:50 (w/v, protein). The viabilities of the DK strains were determined in the presence of low pH and bile salts. Then, yogurt was produced via fermentation with L. casei DK128, an isolate from Kimchi, in the presence of the following additives: CPP, WPC, and WPC hydrolysates (WPCH) generated by alcalase (A) or neutrase (N). The produced yogurts were subjected to various analyses, including viable cell counts (CFU/mL), pH, titratable activity, and sensory testing. After 8 h of fermentation, the pH and titratable activity values of all test samples were 4.2 and 0.9, respectively. The viable counts of LAB were $3.49{\times}10^8$, $5.72{\times}10^8$, $7.01{\times}10^8$, and $6.97{\times}10^8$, for the Control, CPP, A, and N samples, respectively. These results suggest that whey proteins have potential as dietary supplements in functional foods and that WPCH could be used in yogurt as a low-cost alternative to CPP.