• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.574-580
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• 2019

ATP drives the conformational change of the group II chaperonin from the open lid substrate-binding conformation to the closed lid conformation to encapsulate an unfolded protein in the central cavity. It is thought that the folding activity of group II chaperonin is strongly correlated with the ATP-dependent conformational change ability. In order to confirm the dependence of the reaction temperature and ATP concentration of PhCpn, the ATPase activities were measured under different reaction temperatures and ATP concentrations. The maximal ATPase activity of PhCpn was observed at 80℃ and 3 mM ATP concentration. As a result of ATPase activity according to the type of salt ions, the highest activity was observed at 300 mM LiCl among the univalent cations and 5 mM MgCl₂ among the divalent cations, respectively. The values of Km and Vmax for ATP substrate were estimated as 2.17 mM and 833.3 μM/min, respectively. This results provide the enzymatic information of PhCpn when the prolonged and high activities of pharmaceutical and industrial proteins (or enzymes), by using chaperonin molecules, are required.

• Food Industry
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• s.94
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• pp.37-40
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• 1988

1) 본 연구에서 시료로 선정한 충남 서산산 건강(dry ginger)은 수분이 $9.4\%$, 회분이 $8.7\%$ 그리고 alcohol에 의한 추출량이 약 $9\%$이다. 이는 선진국에 채택사용하고 있는 건강의 규격기준에 의하면 양호하다. 2) Non- flavor물질의 추출을 최소화하고 특히 증류과정에서 유효성분 손실을 최소화 할 수 있고, 엑기스내의 용매 잔류량이 인체에 유해하지 않고 추출효율을 높일 수 있는 용매는 ethyl alcohol이다. 3) 널리 사용하고 있는 관류추출(percolation)의 성능을 분석하고 이의 개선방안을제시하였다. - 추출효율을 높이기 위하여 건강(dry ginger)의 입자를 작게하면 압력강하가 증대되어순환되는 용액의 유속을 제어하기가 힘들다. - 입자가 작을 시에는 유체의 흐름이chan-nelling현상을 나타낸다. - 위와 같은 조건에서는 물질 전달속도가 느리므로 추출효율을 증대시킬 수가 없다. - 따라서 percolation추출에 사용되는 건강의 입자크기는 30mesh크기 이상이어야 운전조작이 용이하나 추출효율이 낮으므로, 추출시간 6시간에 회수된 생강엑기스양은 약 $2.5\%$이다. 4) percolation추출의 단점을 보완하기 위하여 기계적교반 추출을 선택하여 다음과 같은 개선점을 찾았다. - 교반형 추출에서는 고 - 액분리시 cake 저항에서 문제가 야기되지 않는 범위까지 건강의 입자를 작게할 수 있으므로 추출효율을 크게 향상시킬 수 있었다. 즉, 작게 분쇄된 건강(30mesh통과$90\%$)을 대상으로 추출시간 3시간에 $7\%$의 회수율로 증대시켰다. 최적 운전조건은 다음과 같다. 건강시료:1kg 시료크기:-30mesh$90\%$ 용매:ethyl alcohol 3$\iota$ 교반속도:900r.p.m 추출온도:상온($15\~25^{\circ}C$) 추출시간:3시간 일차 추출조건과 동일하게 하여 얻어진 엑기스의 수율이 $2\~2.5\%$이므로 총엑기스의 수율은 건강(dry ginger)무게기준으로 $8.5\~9.5\%$이었다. 5) 교반추출의 효율이 개선되었다 하더라도 추출물의 분리가 용이하여야만 공정의 이용이 가능하다. 그러므로 교반추출후 고 - 액분리를 위하여 정압여과 장치를 이용하여 여과시 cake의 평균 비저항을 얻었으며, 이의 값은 $4.31\times10^8cm\;/\;gr$으로서 여과에는 어려움이 없다는 것을 의미한다. 따라서 추출속도와 효율이 상대적으로 우수한 교반형 추출기의 가능성을 예시할 수 있음을 알 수 있었다. 6) 추출물을 농축과정에서 휘발성 oil의 손실을 최대로 줄이기 위해서는 단순증류를 하지 말고 분별증류를 수행하여야 하며, gingerol과 같은 중요성분의 열분해 반응을 억제하기 위해서는 열전달 효율을 증대시켜 증류조작을 원활히 수행하여야 하므로, still내의 농축물을 계속 교반시켜야 하며 감압상태에서 증류온도는 $40\~50^{\circ}C$로 유지시키는 것이 가장 바람직하다. 7) Ethyl alcohol로 추출된 엑기스내의 수분이나 회분함량은 외국산 제품에 비하여 약간 낮고, 반면에 조지방 및 조단백 성분의 함량은 약간 높게 나타나고 있어 대체적으로 본 연구에서 얻어진 엑기스내의 비풍미성분(non- fla-vour component) 함량은 외국산에 비하여 많은 차이가 없다. 8) 수입 외국산에 비하여 국산엑기스(본 연구에서 ethyl alcohol로 추출)내의 무기성분등의 함량은 비교적 낮은 편이다. 9) 건강에서부터 oleoresin을 얻어 paradol을 제거시킨 후 순수한 gingerol을 분리하여 IR과 NMR로 확인한 결과, 국산건강의 엑기스에는 주로 6-gingerol이고 약간의 10-gingerol이 함유된 것으로 나타났다. 10) 순수하게 분리된 gingerol을 열분석(TGA와 DTG)한 결과 약 $75^{\circ}C$에서 gingerol의 열분해 반응이 일어남을 알수 있었다. 11) 건강 분말시료와 엑기스내의 미생물 검사 결과 건강분말에서는 세균수가 많이 존재하는 것으로 나타났으나, 이는 ethyl alcohol로 추출하는 공정 중 대부분의 균들이 사멸된 것으로 나타났다. 12) 관능적 측면에선, 본 연구에서 제조한 엑기스와 수입엑기스를 비교한 결과 생강 특유의 맛은 비슷했으나, 수입엑기스에서는 쓴맛과 톱밥냄새를 느낀다는 결과를 나타내었으며 전체적인 종합적 풍미는 국산 건강엑기스가 좋은 것으로 나타났다.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.26-32
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• 2013

Butanol-resistant bacteria were isolated from butanol solvent. The cell growth of isolated strains declined with increasing concentrations of butanol, and isolated strain BRS02 displayed more resistance to 12.5 g/L of butanol than other isolated strains. In addition, strain BRS251, which was resistant to even higher concentrations of butanol, was developed by the mutation of BRS02 using UV. BRS251 could grow in LB medium containing up to 17.5 g/L of butanol, 32.5 g/L of propanol, or 6 g/L of pentanol, whereas the control strain Escherichia coli was found to be tolerant to 7.5 g/L of butanol, 20 g/L of propanol, or 2 g/L of pentanol. The isolated BRS02, a Gram(+) bacterium seen to have a cocci form under the microscope, grew in 6.5% NaCl. According to biochemical tests, BRS02 can metabolize and produce acid with D-galactose, D-maltose, D-mannitol, D-mannose, methyl-${\beta}$-Dglucopyranoside, D-ribose, sucrose, or D-trehalose, as carbon sources. Also, this strain showed resistance to bacitracin, vibriostatic agent O/129, and optochin, alongside positive activities for arginine dihydrolase, ${\alpha}$-glucosidase, and urease. The BRS02 strain was identified as Staphylococcus sp. by analyses of the 16S rRNA gene, phylogenetic tree, and biochemical tests.

• Journal of Life Science
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• v.25 no.12
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• pp.1339-1346
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• 2015

The aim of this study is to increase production of carotenoids in recombinant Escherichia coli by Archaea chaperonin. The carotenoids are a widely distributed class of structurally and functionally diverse yellow, orange, and red natural pigments. These pigments are synthesized in bacteria, algae, fungi, and plants, and have been widely used as a feed supplement from poultry rearing to aquaculture. Carotenoids also exhibit diverse biological properties, such as strong antioxidant and antitumor activities, and enhancement of immune responses. In the microbial world, carotenoids are present in both anoxygenic and oxygenic photosynthetic bacteria and algae and in many fungi. We have previously reported cloning and functional analysis of the carotenoid biosynthesis genes from Paracoccus haeundaensis. The carotenogenic gene cluster involved in astaxanthin production contained seven carotenogenic genes (crtE, crtB, crtI, crtY, crtZ, crtW and crtX genes) and recombinant Escherichia coli harboring seven carotenogenic genes from Paracoccus haeundaensis produced 400 μg/g dry cell weight (DCW) of astaxanthin. In order to increase production of astaxanthin, we have co-expressed chaperone genes (ApCpnA and ApCpnB) in recombinant Escherichia coli harboring the astaxanthin biosynthesis genes. This engineered Escherichia coli strain containing both chaperone gene and astaxanthin biosynthesis gene cluster produced 890 μg/g DCW of astaxanthin, resulting 2-fold increased production of astaxanthin.

• Korean Journal of Food Science and Technology
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• v.46 no.6
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• pp.710-715
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• 2014

To date, the quality and safety of frozen bokbunja have not been clearly assessed. To produce high-quality frozen bokbunja, the optimal freeze-thaw conditions need to be explored. The most popular cultivar (Rubus occidentalis) in Korea was selected for this study. To determine the changes in the quality of frozen R. occidentalis berries, different freezing temperatures were used. The berries were frozen at -20, -45, and $-70^{\circ}C$ immediately after harvest. The drip ratio, hardness, pH, sugar content, color, and anthocyanidin content of the frozen and thawed samples were analyzed. The drip ratio, sugar content, and hardness of the berries correlated significantly with the freezing temperatures. The color and pH of the berries were not significantly affected by the freezing conditions. Frozen leaks between cells reduced significantly with decreasing temperatures. The freeze-thawing process significantly reduced the total aerobic bacteria and inhibited the growth of yeast/mold in the berries to about 2 log scales.

• Journal of Life Science
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• v.28 no.10
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• pp.1244-1253
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• 2018

Rumen microbiome consists of a wide variety of microorganisms, such as bacteria, archaea, protozoa, fungi, and viruses, that are in a symbiotic relationship in a strict anaerobic environment in the rumen. These rumen microbiome, a vital maker, play a significant role in feed fermentation within the rumen and produce different volatile fatty acids (VFAs). VFAs are essential for energy metabolism and protein synthesis of the host animal, even though emission of methane gas after feed fermentation is considered a negative indicator of loss of dietary energy of the host animal. To improve rumen microbial efficiency, a variety of approaches, such as feed formulation, the addition of natural feed additives, dietary feed-microbes, etc., have taken to increase ruminant performance. Recently with the application of high-throughput sequencing or next-generation sequencing technologies, especially for metagenomics and metatranscriptomics of rumen microbiomes, our understanding of rumen microbial diversity and function has significantly increased. The metaproteome and metabolome provide deeper insights into the complicated microbial network of the rumen ecosystem and its response to different ruminant diets to improve efficiency in animal production. This review summarized some recent advances of rumen microbiome techniques, especially "meta-omics," viz. metagenomic, metatranscriptomic, metaproteomic, and metabolomic techniques to increase feed fermentation and utilization in ruminants.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.7
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• pp.1072-1078
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• 2015

To maintain high quality and microbiological safety of paprika during storage for export, paprika samples after harvest were treated with 75 ppmv chlorine dioxide ($ClO_2$) gas and stored at $8^{\circ}C$, which is the optimal storage temperature, for 30 days. $ClO_2$ gas treatment reduced initial populations of total aerobic bacteria in samples by 1.62 log CFU/g as well as yeast and molds by 1.45 log CFU/g compared to those of the control. During storage, weight loss of all samples increased, and samples treated with $ClO_2$ gas showed lower weight loss than the control. In addition, total soluble solid and total phenolic contents were not significantly different between the samples during storage, whereas vitamin C content and hardness of all samples decreased. Hunter L, a, and b values of paprika samples were not significantly different between the treatments. These results suggest that $ClO_2$ gas treatment can be effective for improving microbiological safety and maintaining high quality of paprika during storage.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.267-271
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• 2015

This study aimed to determine the optimal freezing temperature for preserving mulberries. Mulberries were frozen at -20, -45, and $-70^{\circ}C$ immediately after harvesting. After 24 h, frozen mulberries were stored at $-20^{\circ}C$ for two months and then thawed at $4^{\circ}C$ and room temperature. Frozen and thawed mulberries did not differ significantly in color and pH from fresh mulberries. However, the content of anthocyanidin and sugar, and the hardness of mulberry significantly decreased after feeze-thawing. Drip loss of the thawed berries increased as the freezing temperature decreased. A comparison among cross-section images of mulberries frozen at different temperatures did not show any significant differences. However, after thawing at $4^{\circ}C$ or room temperature, the total number of aerobic bacteria found in mulberry decreased more than ten times. Consequently, the freezing temperature showed no significant effect on the overall quality of the mulberry.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.362-367
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• 2009

Among total 176 strains with antialgal effects isolated from So-ok stream in Korea, Pseudomonas aeruginosa AJ1 showed the highest removal efficiency for an algal species Microcystis aeruginosa (clear zone of diameter 50.0 mm on algal lawn after 20 days). The algal growth was suppressed even when the supernatant of AJ1 culture was applied, suggesting that extracellular substances are responsible for its antialgal activity. The removal activity of AJ1 was optimal under the following condition: pH 8, $30^{\circ}C$, and mannitol as a carbon source. The antialgal activity of AJ1 appeared to be dependent of the growth phase of M. aeruginosa, i.e., the highest at the early phase, but not its own phase. As expected, the algicidal effect was improved as the amount of the treated supernatant was increased; the highest removal efficiency (80.3%) was achieved when 40 ml/L of the supernatant was used. Interestingly, however, the removal rate was opposite. The highest removal rate ($8.2{\mu}g$ chl-a/ml supernatant/day) was achieved when low concentration (10 ml/L) was applied. These results suggest that P. aeruginosa AJ1 is a promising biological agent to control the problematic algal bloom.

• Journal of Life Science
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• v.26 no.2
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• pp.265-274
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• 2016

Toxin-antitoxin (TA) systems are ubiquitous genetic modules that are evolutionally conserved in bacteria and archaea. TA systems composed of an intracellular toxin and its antidote (antitoxin) are currently classified into five types. Commonly, activation of toxins under stress conditions inhibits diverse cellular processes and consequently induces cell death or reversible growth inhibition. These effects of toxins play various physiological roles in such as regulation of gene expression, growth control (stress response), programmed cell arrest, persister cells, programmed cell death, phage protection, stabilization of mobile genetic elements or postsegregational killing of plasmid-free cells. Accordingly, bacterial TA systems are commonly considered as stress-responsive genetic modules. However, molecule screening for activation of toxin in TA system is available as development of antimicrobial agents. In addition, cytotoxic effect induced by toxin is used as effective cloning method with antitoxic effect of antitoxin; consequently cells containing cloning vector inserted a target gene can survive and false-positive transformants are removed. Also, TA system is applicable to efficient single protein production in biotechnology industry because toxins that are site-specific ribonuclease inhibit protein synthesis except for target protein. Furthermore, some TA systems that induce apoptosis in eukaryotic cells such as cancer cells or virus-infected cells would have a wide range of applications in eukaryotes, and it will lead to new ways of treating human disease. In this review, we summarize the current knowledge on bacterial TA systems and their applications.