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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Microbiology and Biotechnology
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The Korean Society for Applied Microbiology and Biotechnology
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Volume & Issues
Volume 23, Issue 12 - Dec 2013
Volume 23, Issue 11 - Nov 2013
Volume 23, Issue 10 - Oct 2013
Volume 23, Issue 9 - Sep 2013
Volume 23, Issue 8 - Aug 2013
Volume 23, Issue 7 - Jul 2013
Volume 23, Issue 6 - Jun 2013
Volume 23, Issue 5 - May 2013
Volume 23, Issue 4 - Apr 2013
Volume 23, Issue 3 - Mar 2013
Volume 23, Issue 2 - Feb 2013
Volume 23, Issue 1 - Jan 2013
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Diversity of Halophilic Archaea in Fermented Foods and Human Intestines and Their Application
Lee, Han-Seung ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1645~1653
DOI : 10.4014/jmb.1308.08015
Archaea are prokaryotic organisms distinct from bacteria in the structural and molecular biological sense, and these microorganisms are known to thrive mostly at extreme environments. In particular, most studies on halophilic archaea have been focused on environmental and ecological researches. However, new species of halophilic archaea are being isolated and identified from high salt-fermented foods consumed by humans, and it has been found that various types of halophilic archaea exist in food products by culture-independent molecular biological methods. In addition, even if the numbers are not quite high, DNAs of various halophilic archaea are being detected in human intestines and much interest is given to their possible roles. This review aims to summarize the types and characteristics of halophilic archaea reported to be present in foods and human intestines and to discuss their application as well.
Fungal Diversity of Rice Straw for Meju Fermentation
Kim, Dae-Ho ; Kim, Seon-Hwa ; Kwon, Soon-Wo ; Lee, Jong-Kyu ; Hong, Seung-Beom ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1654~1663
DOI : 10.4014/jmb.1307.07071
Rice straw is closely associated with meju fermentation and it is generally known that the rice straw provides meju with many kinds of microorganisms. In order to elucidate the origin of meju fungi, the fungal diversity of rice straw was examined. Rice straw was collected from 12 Jang factories where meju are produced, and were incubated under nine different conditions by altering the media (MEA, DRBC, and DG18), and temperature (
). In total, 937 strains were isolated and identified as belonging to 39 genera and 103 species. Among these, Aspergillus, Cladosporium, Eurotium, Fusarium, and Penicillium were the dominant genera. Fusarium asiaticum (56.3%), Cladosporium cladosporioides (48.6%), Aspergillus tubingensis (37.5%), A. oryzae (31.9%), Eurotium repens (27.1%), and E. chevalieri (25.0%) were frequently isolated from the rice straw obtained from many factories. Twelve genera and 40 species of fungi that were isolated in the rice straw in this study were also isolated from meju. Specifically, A. oryzae, C. cladosporioides, E. chevalieri, E. repens, F. asiaticum, and Penicillium polonicum (11.8%), which are abundant species in meju, were also isolated frequently from rice straw. C. cladosporioides, F. asiaticum, and P. polonicum, which are abundant in the low temperature fermentation process of meju fermentation, were frequently isolated from rice straw incubated at
, whereas A. oryzae, E. repens, and E. chevalieri, which are abundant in the high temperature fermentation process of meju fermentation, were frequently isolated from rice straw incubated at
. This suggests that the mycobiota of rice straw has a large influence in the mycobiota of meju. The influence of fungi on the rice straw as feed and silage for livestock, and as plant pathogens for rice, are discussed as well.
Hfq and ArcA Are Involved in the Stationary Phase-Dependent Activation of Salmonella Pathogenicity Island 1 (SPI1) Under Shaking Culture Conditions
Lim, Sangyong ; Yoon, Hyunjin ; Kim, Minjeong ; Han, Ahreum ; Choi, Jihae ; Choi, Jeongjoon ; Ryu, Sangryeol ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1664~1672
DOI : 10.4014/jmb.1305.05022
In Salmonella enterica serovar Typhimurium, many genes encoded within Salmonella pathogenicity island 1 (SPI1) are required to induce intestinal/diarrheal disease. In this study, we compared the expression of four SPI1 genes (hilA, invF, prgH, and sipC) under shaking and standing culture conditions and found that the expression of these genes was highest during the transition from the exponential to stationary phase under shaking conditions. To identify regulators associated with the stationary phase-dependent activation of SPI1, the effects of selected regulatory genes, including relA/spoT (ppGpp), luxS, ihfB, hfq, and arcA, on the expression of hilA and invF were compared under shaking conditions. Mutations in the hfq and arcA genes caused a reduction in hilA and invF expression (more than 2-fold) in the early stationary phase only, whereas the lack of ppGpp and IHF decreased hilA and invF gene expression during the entire stationary phase. We also found that hfq and arcA mutations caused a reduction of hilD expression upon entry into the stationary phase under shaking culture conditions. Taken together, these results suggest that Hfq and ArcA regulate the hilD promoter, causing an accumulation of HilD, which can trigger a stationary phase-dependent activation of SPI1 genes under shaking culture conditions.
Effects of Nutritional and Environmental Conditions on Planktonic Growth and Biofilm Formation of Citrobacter werkmanii BF-6
Zhou, Gang ; Li, Long-Jie ; Shi, Qing-Shan ; Ouyang, You-Sheng ; Chen, Yi-Ben ; Hu, Wen-Feng ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1673~1682
DOI : 10.4014/jmb.1307.07041
Citrobacter sp. is a cause of significant opportunistic nosocomial infection and is frequently found in human and animal feces, soil, and sewage water, and even in industrial waste or putrefaction. Biofilm formation is an important virulence trait of Citrobacter sp. pathogens but the process and characteristics of this formation are unclear. Therefore, we employed in vitro assays to study the nutritional and environmental parameters that might influence biofilm formation of C. werkmanii BF-6 using 96-well microtiter plates. In addition, we detected the relative transcript levels of biofilm formation genes by RT-PCR. Our results indicated that the capacity of C. werkmanii BF-6 to form biofilms was affected by culture temperature, media, time, pH, and the osmotic agents glucose, sucrose, NaCl, and KCl. Confocal laser scanning microscopy results illustrated that the structure of biofilms and extracellular polysaccharide was influenced by 100 mM NaCl or 100 mM KCl. In addition, nine biofilm formation genes (bsmA, bssR, bssS, csgD, csgE, csgF, mrkA, mrkB, and mrkE) were found to contribute to planktonic and biofilm growth. Our data suggest that biofilm formation by C. werkmanii BF-6 is affected by nutritional and environmental factors, which could pave the way to the prevention and elimination of biofilm formation using proper strategies.
Elucidation of the Regulation of Ethanol Catabolic Genes and ptsG Using a glxR and Adenylate Cyclase Gene (cyaB) Deletion Mutants of Corynebacterium glutamicum ATCC 13032
Subhadra, Bindu ; Lee, Jung-Kee ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1683~1690
DOI : 10.4014/jmb.1310.10031
The cyclic AMP receptor protein (CRP) homolog, GlxR, controls the expression of several genes involved in the regulation of diverse physiological processes in Corynebacterium glutamicum. In silico analysis has revealed the presence of glxR binding sites upstream of genes ptsG, adhA, and ald, encoding glucose-specific phosphotransferase system protein, alcohol dehydrogenase (ADH), and acetaldehyde dehydrogenase (ALDH), respectively. However, the involvement of the GlxR-cAMP complex on the expression of these genes has been explored only in vitro. In this study, the expressions of ptsG, adhA, and ald were analyzed in detail using an adenylate cyclase gene (cyaB) deletion mutant and glxR deletion mutant. The specific activities of ADH and ALDH were increased in both the mutants in glucose and glucose plus ethanol media, in contrast to the wild type. In accordance, the promoter activities of adhA and ald were derepressed in the cyaB mutant, indicating that glxR acts as a repressor of adhA. Similarly, both the mutants exhibited derepression of ptsG regardless of the carbon source. These results confirm the involvement of GlxR on the expression of important carbon metabolic genes; adhA, ald, and ptsG.
Anti-Inflammatory Activity of Ethanolic Extract of Sargassum micracanthum
Jeong, Da-Hyun ; Kim, Koth-Bong-Woo-Ri ; Kim, Min-Ji ; Kang, Bo-Kyeong ; Ahn, Dong-Hyun ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1691~1698
DOI : 10.4014/jmb.1311.11025
The anti-inflammatory effects of Sargassum micracanthum ethanol extract (SMEE) was investigated using LPS-induced inflammatory response in this study. As a result, there was no cytotoxicity in the macrophage proliferation treated with SMEE compared with the control. SMEE inhibited production of nitric oxide and cytokines (IL-6, TNF-
, and IL-
) in a dose-dependent manner. In addition, the expression of inducible nitric oxide synthase and cyclooxygenase 2 were suppressed via inhibition of nuclear factor
p65 expression by SMEE treatment. The formation of edema in the mouse ear was reduced at the highest dose tested compared with that in the control, and reduction of ear thickness was observed in histological analysis. Moreover, in an acute toxicity test, no mortalities occurred in mice administered 5,000 mg/kg body weight of SMEE over a 2-week observation period. These results suggest that SMEE may have significant effects on inflammatory mediators and be a potential anti-inflammatory therapeutic material.
Characterization and Cofactor Binding Mechanism of a Novel NAD(P)H-Dependent Aldehyde Reductase from Klebsiella pneumoniae DSM2026
Ma, Cheng-Wei ; Zhang, Le ; Dai, Jian-Ying ; Xiu, Zhi-Long ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1699~1707
DOI : 10.4014/jmb.1307.07015
During the fermentative production of 1,3-propanediol under high substrate concentrations, accumulation of intracellular 3-hydroxypropionaldehyde will cause premature cessation of cell growth and glycerol consumption. Discovery of oxidoreductases that can convert 3-hydroxypropionaldehyde to 1,3-propanediol using NADPH as cofactor could serve as a solution to this problem. In this paper, the yqhD gene from Klebsiella pneumoniae DSM2026, which was found encoding an aldehyde reductase (KpAR), was cloned and characterized. KpAR showed broad substrate specificity under physiological direction, whereas no catalytic activity was detected in the oxidation direction, and both NADPH and NADH can be utilized as cofactors. The cofactor binding mechanism was then investigated employing homology modeling and molecular dynamics simulations. Hydrogen-bond analysis showed that the hydrogen-bond interactions between KpAR and NADPH are much stronger than that for NADH. Free-energy decomposition dedicated that residues Gly37 to Val41 contribute most to the cofactor preference through polar interactions. In conclusion, this work provides a novel aldehyde reductase that has potential applications in the development of novel genetically engineered strains in the 1,3-propanediol industry, and gives a better understanding of the mechanisms involved in cofactor binding.
Rapid Detection of Viable Escherichia coli O157 by Coupling Propidium Monoazide with Loop-Mediated Isothermal Amplification
Zhao, Xihong ; Wang, Jun ; Forghani, Fereidoun ; Park, Joong-Hyun ; Park, Myoung-Su ; Seo, Kun-Ho ; Oh, Deog-Hwan ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1708~1716
DOI : 10.4014/jmb.1306.06003
Conventional molecular detection methods cannot distinguish between viable and dead Escherichia coli O157 cells. In this study, the loop-mediated isothermal amplification (LAMP) method combined with propidium monoazide (PMA) treatment was developed to selectively detect viable E. coli O157 cells. Four primers, including outer primers and inner primers, were specially designed for the recognition of six distinct sequences on the serogroups (O157) of the specific rfbE gene of the E. coli O157 genome. PMA selectively penetrated through the compromised cell membranes and intercalated into DNA. Amplification of DNA from dead cells was completely inhibited by
PMA, whereas the DNA derived from viable cells was amplified remarkably within 1 h by PMA-LAMP. Exhibiting high sensitivity and specificity, PMA-LAMP is a suitable method for evaluating the inactivation efficacy of slightly acidic electrolyzed water in broth. PMA-LAMP can selectively detect viable E. coli O157 cells. This study offers a novel molecular detection method to distinguish between viable and dead E. coli O157 cells.
Microbial Floral Dynamics of Chinese Traditional Soybean Paste (Doujiang) and Commercial Soybean Paste
Gao, Xiuzhi ; Liu, Hui ; Yi, Xinxin ; Liu, Yiqian ; Wang, Xiaodong ; Xu, Wensheng ; Tong, Qigen ; Cui, Zongjun ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1717~1725
DOI : 10.4014/jmb.1306.06004
Traditional soybean paste from Shandong Liangshan and Tianyuan Jiangyuan commercial soybean paste were chosen for analysis and comparison of their bacterial and fungal dynamics using denaturing gel gradient electrophoresis and 16S rRNA gene clone libraries. The bacterial diversity results showed that more than 20 types of bacteria were present in traditional Shandong soybean paste during its fermentation process, whereas only six types of bacteria were present in the commercial soybean paste. The predominant bacteria in the Shandong soybean paste were most closely related to Leuconostoc spp., an uncultured bacterium, Lactococcus lactis, Bacillus licheniformis, Bacillus spp., and Citrobacter freundii. The predominant bacteria in the Tianyuan Jiangyuan soybean paste were most closely related to an uncultured bacterium, Bacillus licheniformis, and an uncultured Leuconostoc spp. The fungal diversity results showed that 10 types of fungi were present in the Shandong soybean paste during the fermentation process, with the predominant fungi being most closely related to Geotrichum spp., an uncultured fungal clone, Aspergillus oryzae, and yeast species. The predominant fungus in the commercial soybean paste was Aspergillus oryzae.
Development of Indole-3-Acetic Acid-Producing Escherichia coli by Functional Expression of IpdC, AspC, and Iad1
Romasi, Elisa Friska ; Lee, Jinho ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1726~1736
DOI : 10.4014/jmb.1308.08082
Biosynthesis of indole-3-acetic acid (IAA) via the indole-3-pyruvic acid pathway involves three kinds of enzymes; aminotransferase encoded by aspC, indole-3-pyruvic acid decarboxylase encoded by ipdC, and indole-3-acetic acid dehydrogenase encoded by iad1. The ipdC from Enterobacter cloacae ATCC 13047, aspC from Escherichia coli, and iad1 from Ustilago maydis were cloned and expressed under the control of the tac and sod promoters in E. coli. According to SDS-PAGE and enzyme activity, IpdC and Iad1 showed good expression under the control of
, whereas AspC was efficiently expressed by
originating from Corynebacterium glutamicum. The activities of IpdC, AspC, and Iad1 from the crude extracts of recombinant E. coli Top 10 were 215.6, 5.7, and 272.1 nmol/min/mg-protein, respectively. The recombinant E. coli
expressing IpdC, AspC, and Iad1 produced about 1.1 g/l of IAA and 0.13 g/l of tryptophol (TOL) after 48 h of cultivation in LB medium with 2 g/l tryptophan. To improve IAA production, a tnaA gene mediating indole formation from tryptophan was deleted. As a result, E. coli IAA68 with expression of the three genes produced 1.8 g/l of IAA, which is a 1.6-fold increase compared with wild-type
harboring the same plasmids. Moreover, the complete conversion of tryptophan to IAA was achieved by E. coli IAA68. Finally, E. coli IAA68 produced 3.0 g/l of IAA after 24 h cultivation in LB medium supplemented with 4 g/l of tryptophan.
Enhanced Salt Stress Tolerance in Transgenic Potato Plants Expressing IbMYB1, a Sweet Potato Transcription Factor
Cheng, Yu-Jie ; Kim, Myoung-Duck ; Deng, Xi-Ping ; Kwak, Sang-Soo ; Chen, Wei ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1737~1746
DOI : 10.4014/jmb.1307.07024
IbMYB1, a transcription factor (TF) for R2R3-type MYB TFs, is a key regulator of anthocyanin biosynthesis during storage of sweet potatoes. Anthocyanins provide important antioxidants of nutritional value to humans, and also protect plants from oxidative stress. This study aimed to increase transgenic potatoes' (Solanum tuberosum cv. LongShu No.3) tolerance to environmental stress and enhance their nutritional value. Transgenic potato plants expressing IbMYB1 genes under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter (referred to as SM plants) were successfully generated through Agrobacterium-mediated transformation. Two representative transgenic SM5 and SM12 lines were evaluated for enhanced tolerance to salinity, UV-B rays, and drought conditions. Following treatment of 100 mM NaCl, seedlings of SM5 and SM12 lines showed less root damage and more shoot growth than control lines expressing only an empty vector. Transgenic potato plants in pots treated with 400 mM NaCl showed high amounts of secondary metabolites, including phenols, anthocyanins, and flavonoids, compared with control plants. After treatment of 400 mM NaCl, transgenic potato plants also showed high DDPH radical scavenging activity and high PS II photochemical efficiency compared with the control line. Furthermore, following treatment of NaCl, UV-B, and drought stress, the expression levels of IbMYB1 and several structural genes in the flavonoid biosynthesis such as CHS, DFR, and ANS in transgenic plants were found to be correlated with plant phenotype. The results suggest that enhanced IbMYB1 expression affects secondary metabolism, which leads to improved tolerance ability in transgenic potatoes.
The Effect of Spent Medium Recycle on Cell Proliferation, Metabolism and Baculovirus Production by the Lepidopteran Se301 Cell Line Infected at Very Low MOI
Beas-Catena, Alba ; Sanchez-Miron, Asterio ; Garcia-Camacho, Francisco ; Contreras-Gomez, Antonio ; Molina-Grima, Emilio ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1747~1756
DOI : 10.4014/jmb.1305.05067
The aim of this paper was to study the effect of spent medium recycle on Spodoptera exigua Se301 cell line proliferation, metabolism, and baculovirus production when grown in batch suspension cultures in Ex-Cell 420 serum-free medium. The results showed that the recycle of 20% of spent medium from a culture in mid-exponential growth phase improved growth relative to a control culture grown in fresh medium. Although both glucose and glutamine were still present at the end of the growth phase, glutamate was always completely exhausted. The pattern of the specific glucose and lactate consumption and production rates, as well as the specific glutamine and glutamate consumption rates, suggests a metabolic shift at spent medium recycle values of over 60%, with a decrease in the efficiency of glucose utilization and an increase in glutamate consumption to fuel energy metabolism. Baculovirus infection provoked a change in the metabolic pattern of Se301 cells, although a beneficial effect of spent medium recycle was also observed. Both growth rate and maximum viable cell density decreased relative to uninfected cultures. The efficiency of glucose utilization was dramatically reduced in those cultures containing the lowest percentages of spent medium, whereas glutamine and glutamate consumption was modulated, thereby suggesting that infected cells were devoted to virus replication, retaining their ability to incorporate the nutrients required to support viral replication. Recycle of 20% of spent medium increased baculovirus production by around 90%, thus showing the link between cell growth and baculovirus production.
Media Optimization for Laccase Production by Trichoderma harzianum ZF-2 Using Response Surface Methodology
Gao, Huiju ; Chu, Xiang ; Wang, Yanwen ; Zhou, Fei ; Zhao, Kai ; Mu, Zhimei ; Liu, Qingxin ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1757~1764
DOI : 10.4014/jmb.1302.02057
Trichoderma harzianum ZF-2 producing laccase was isolated from decaying samples from Shandong, China, and showed dye decolorization activities. The objective of this study was to optimize its culture conditions using a statistical analysis of its laccase production. The interactions between different fermentation parameters for laccase production were characterized using a Plackett-Burman design and the response surface methodology. The different media components were initially optimized using the conventional one-factor-at-a-time method and an orthogonal test design, and a Plackett-Burman experiment was then performed to evaluate the effects on laccase production. Wheat straw powder, soybean meal, and
were all found to have a significant influence on laccase production, and the optimal concentrations of these three factors were then sequentially investigated using the response surface methodology with a central composite design. The resulting optimal medium components for laccase production were determined as follows: wheat straw powder 7.63 g/l, soybean meal 23.07 g/l,
0.51 g/l, Tween-20 1 g/l,
1 g/l, and
0.6 g/l. Using this optimized fermentation method, the yield of laccase was increased 59.68 times to 67.258 U/ml compared with the laccase production with an unoptimized medium. This is the first report on the statistical optimization of laccase production by Trichoderma harzianum ZF-2.
Electricity Generation by Microbial Fuel Cell Using Microorganisms as Catalyst in Cathode
Jang, Jae Kyung ; Kan, Jinjun ; Bretschger, Orianna ; Gorby, Yuri A. ; Hsu, Lewis ; Kim, Byung Hong ; Nealson, Kenneth H. ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1765~1773
DOI : 10.4014/jmb.1310.10117
The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were
, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode (
cathode compartment) than the abiotic cathode MFC (
cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.
The Presence of Significant Methylotrophic Population in Biological Activated Carbon of a Full-Scale Drinking Water Plant
Kim, Tae Gwan ; Moon, Kyung-Eun ; Cho, Kyung-Suk ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1774~1778
DOI : 10.4014/jmb.1307.07048
Methylotrophs within biological activated carbon (BAC) systems have not received attention although they are a valuable biological resource for degradation of organic pollutants. In this study, methylotrophic populations were monitored for four consecutive seasons in BAC of an actual drinking water plant, using ribosomal tag pyrosequencing. Methylotrophs constituted up to 5.6% of the bacterial community, and the methanotrophs Methylosoma and Methylobacter were most abundant. Community comparison showed that the temperature was an important factor affecting community composition, since it had an impact on the growth of particular methylotrophic genera. These results demonstrated that BAC possesses a substantial methylotrophic activity and harbors the relevant microbes.
Memory-Enhancing Effects of Silk Fibroin-Derived Peptides in Scopolamine-Treated Mice
Kang, Yong Koo ; Lee, Woojoo ; Kang, Byunghoon ; Kang, Hannah ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1779~1784
DOI : 10.4014/jmb.1308.08059
Although enzyme-hydrolyzed silk fibroin has been reported to enhance cognitive function before, it has been still unknown which peptides can improve memory. Here we report that amino acid sequences of three novel peptides were identified from fibroin hydrolysate. Fibroin hydrolysate was obtained by hydrolysis with protease after partial hydrolysis with 5M
. Synthesized peptides derived from these sequences improved scopolamine-induced memory impairments in mice. We confirmed this hydrolysate had effects that improved learning and memory abilities by performing the Rey-Kim test. From this hydrolysate of silk fibroin, amino acid sequences of eight peptides were identified by LC-MS/MS. Three peptides (GAGAGTGSSGFGPY, GAGAGSGAGSGAGAGSGAGAGY, and SGAGSGAGAGSGAGAGSGA) were synthesized to investigate whether they could improve memory. Passive avoidance test and Morris water maze test were performed, and all peptides showed memory-enhancing abilities on scopolamine-induced memory impairments in mice. In this study, we identified three novel peptides that could improve memory, and that silk fibroin hydrolysate was a mixture of various active peptides that could enhance memory.
SIRT1 Suppresses Activating Transcription Factor 4 (ATF4) Expression in Response to Proteasome Inhibition
Woo, Seon Rang ; Park, Jeong-Eun ; Kim, Yang Hyun ; Ju, Yeun-Jin ; Shin, Hyun-Jin ; Joo, Hyun-Yoo ; Park, Eun-Ran ; Hong, Sung Hee ; Park, Gil Hong ; Lee, Kee-Ho ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1785~1790
DOI : 10.4014/jmb.1309.09027
The synthetic machinery of ATF4 (activating transcription factor 4) is activated in response to various stress conditions involved in nutrient restriction, endoplasmic reticulum homeostasis, and oxidation. Stress-induced inhibition of proteasome activity triggers the unfolded protein response and endoplasmic reticulum stress, where ATF4 is crucial for consequent biological events. In the current study, we showed that the
-dependent deacetylase, SIRT1, suppresses ATF4 synthesis during proteasome inhibition. SIRT1 depletion via transfection of specific siRNA into HeLa cells resulted in a significant increase in ATF4 protein, which was observed specifically in the presence of the proteasome inhibitor MG132. Consistent with SIRT1 depletion data, transient transfection of cells with SIRT1-overexpressing plasmid induced a decrease in the ATF4 protein level in the presence of MG132. Interestingly, however, ATF4 mRNA was not affected by SIRT1, even in the presence of MG132, indicating that SIRT1-induced suppression of ATF4 synthesis occurs under post-transcriptional control. Accordingly, we propose that SIRT1 serves as a negative regulator of ATF4 protein synthesis at the post-transcriptional level, which is observed during stress conditions, such as proteasome inhibition.
Transcriptomic Analysis of Genes Modulated by Cyclo(
-Proline) in Vibrio vulnificus
Kim, In Hwang ; Son, Jee-Soo ; Wen, Yancheng ; Jeong, Sang-Min ; Min, Ga-Young ; Park, Na-Young ; Lee, Keun-Woo ; Cho, Yong-Joon ; Chun, Jongsik ; Kim, Kun-Soo ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1791~1801
DOI : 10.4014/jmb.1308.08068
Diketopiperazine is produced by various organisms, including bacteria, fungi, and animals, and has been suggested as a novel signal molecule involved in the modulation of genes with various biological functions. Vibrio vulnificus, which causes septicemia in humans, produces cyclo(
-proline) (cFP). To understand the biological roles of cFP, the effect of the compound on the expression of the total mRNA in V. vulnificus was assessed by next-generation sequencing. Based on the transcriptomic analysis, we classified the cFP-regulated genes into functional categories and clustered them according to the expression patterns resulted from treatment with cFP. From a total of 4,673 genes, excepting the genes encoding tRNA in V. vulnificus, 356 genes were up-regulated and 602 genes were down-regulated with an RPKM (reads per kilobase per million) value above 3. The genes most highly induced by cFP comprised those associated with the transport and metabolism of inorganic molecules, particularly iron. The genes negatively regulated by cFP included those associated with energy production and conversion, as well as carbohydrate metabolism. Noticeably, numerous genes related with biofilm formation were modulated by cFP. We demonstrated that cFP interferes significantly with the biofilm formation of V. vulnificus.
Ginsenoside Rb1 is Transformed into Rd and Rh2 by Microbacterium trichothecenolyticum
Kim, Hansoo ; Kim, Jeong-Hoon ; Lee, Phil Young ; Bae, Kwang-Hee ; Cho, Sayeon ; Park, Byoung Chul ; Shin, Heungsop ; Park, Sung Goo ;
Journal of Microbiology and Biotechnology, volume 23, issue 12, 2013, Pages 1802~1805
DOI : 10.4014/jmb.1307.07049
Ginsenosides are the most important ingredient of ginseng and are known to possess many pharmacological and biological effects. Rb1, a major protopanaxadiol ginsenoside, is the most abundant ginsenoside in Panax ginseng C.A Meyer and can be hydrolyzed into more pharmaceutically potent minor ginsenosides. To identify a microorganism that is capable of converting Rb1 into other ginsenosides, we screened 12 Microbacterium spp., and M. trichothecenolyticum was identified as a likely candidate. M. trichothecenolyticum converted Rb1 into Rd and then into Rh2 based on TLC and HPLC analyses of reaction products. This biotransformation method can be easily applied for mass production of Rd and Rh2 by using Rb1.