• Korean Journal of Microbiology
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• v.48 no.3
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• pp.200-206
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• 2012

A bacterial strain capable of synthesizing polyhydroxyalkanoates (PHAs) with an unusual pattern of monomer units was isolated from activated sludge using the enrichment culture technique. The organism, identified as Pseudomonas aeruginosa P-5, produced polyesters consisting of 3-hydroxyvalerate and medium-chain-length (MCL) 3-hydroxyalkanoate monomer units when $C_{-odd}$ alkanoic acids such as nonanoic acid and heptanoic acid were fed as the sole carbon source. Solvent fractionation experiments using chloroform and hexane revealed that the 3-hydroxyalkanoate monomer units in these polyesters were copolymerized. The molar concentration of 3-hydroxyvalerate in the polyesters produced were significantly elevated up to 26 mol% by adding 1.0 g/L valeric acid as the cosubstrate. These copolyesters were sticky with low degrees of crystallinity. The PHA synthase genes were cloned, and the deduced amino acid sequences were determined. P. aeruginosa P-5 possessed genes encoding MCL-PHA synthases (PhaC1 and PhaC2) but lacked the short-chain-length PHA synthase gene, suggesting that the MCL-PHA synthases from P. aeruginosa P-5 are uniquely active for polymerizing (R)-3-hydroxyvaleryl-CoA as well as MCL (R)-3-hydroxyacyl-CoAs.

• Korean Journal of Microbiology
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• v.45 no.3
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• pp.233-238
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• 2009

The expression of Corynebacterium ammoniagenes purF was analyzed by utilizing a plasmid carrying a cat gene fused to the purF promoter region. Adenine and guanine repressed the expression of the purF gene by 20~30% but hypoxanthine did not exert such repressive effect. The expression purF was maximal at the late log phase and remained constant throughout the stationary phase. Promoter $P_{180}$ which was developed in C. glutamicum was also functional in C. ammoniagenes, achieving maximal activity at the late log phase. The promoter outperformed Escherichia coli $P_{tac}$ promoter by 40~50% level. DNA-affinity purification identified a protein which could bind to the promoter region of the purF gene. The protein showed high similarity to the CRP-family transcriptional regulator encoded by NCgl0120 in C. glutamicum. The size of the screened protein agreed with the expected protein size from the ORF NCgl0120. The corresponding gene in C. ammoniagenes encoded a 42 kDa polypeptide composed of 400 amino acids with expected pI of 4.9. The encoded protein showed 14.1% and 15.8% identity with E. coli and Bacillus subtilis PurR, respectively, suggesting that the isolated protein might be a novel type of regulatory protein involved in the regulation of purine metabolism.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.85-92
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• 2008

Pseudomonas aeruginosa is an opportunistic human pathogen, causing a wide variety of infections including cystic fibrosis, microbial keratitis, and burn wound infections. The cell-to-cell signaling mechanism known as quorum sensing (QS) plays a key role in these infections and the QS systems of P. aeruginosa have been most intensively studied. While many literatures that introduce the QS systems of P. aeruginosa have mostly focused on two major acyl-homo serine lactone (acyl-HSL) QS signals, N-3-oxododecanoyl homoserine lactone (3OC12) and N-butanoyl homoserine lactone (C4), several new signal molecules have been discovered and suggested for their significant roles in signaling and virulence of P. aeruginosa. One of them is PQS (Pseudomonas quinolone signal; 2-heptyl-3-hydroxy-4-quinolone), which is now considered as a well-characterized major signal meolecule of P. aeruginosa. In addition, recent researches have also suggested some more putative signal molecules of P. aeruginosa, which are diketopiperazines (DKPs) and pyocyanin. DKPs are cyclic dipeptides and structurally diverse depending on what amino acids are involved in composition. Some DKPs from the culture supernatant of P. aeruginosa are suggested as new diffusible signal molecules, based on their ability to activate Vibrio fischeri LuxR biosensors that are previously considered specific for acyl-HSLs. Pyocyanin (1-hydroxy-5-methyl-phenazine), one of phenazine derivatives produced by P. aeruginosa is a characteristic blue-green pigment and redox-active compound. This has been recently suggested as a terminal signaling factor to upregulate some QS-controlled genes during stationary phase under the mediation of a transcription factor, SoxR. Here, details about these newly emerging signaling molecules of P. aeruginosa are discussed.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.269-277
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• 2016

Erm proteins methylate the specific adenine residue ($A_{2058}$, E. coli numbering) on 23S rRNA to confer the $MLS_B$ (macrolidelincosamide-streptogramin B) antibiotic resistance on a variety of microorganisms ranging from antibiotic producers to pathogens. When phylogenetic tree is constructed, two main clusters come out forming each cluster of Actinobacteria and Firmicutes. Two representative Erm proteins from each cluster were selected and their in vitro methylation activities were compared. ErmS and ErmE from Actinobacteria cluster exhibited much higher activities than ErmB and ErmC' from Firmicutes: 9 fold difference when ErmC' and ErmE were compared and 13 fold between ErmS and ErmB. Most of the difference was observed and presumed to be caused by N-terminal and C-terminal extra region from ErmS and ErmE, respectively because NT59TE in which N-terminal end 59 amino acids was truncated from wild type ErmS exhibited only 22.5% of wild type ErmS activity. Meanwhile, even NT59TE showed three and 2.2 times more activity when it was compared to ErmB and C, respectively, suggesting core region from antibiotic producers contains extra structure enabling higher activity. This is suggested to be possible through the extra region of 197RWS199 (from both ErmS and ErmE), 261GVGGSLY267 (from ErmS), and 261GVGGNIQ267 (from ErmE) and 291SVV293 (from ErmS) and 291GAV293 (from ErmE) by multiple sequence alignment.

• The Korean Journal of Mycology
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• v.13 no.3
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• pp.131-139
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• 1985

To find antitumor constituents in the shake cultured mycelia of Agaricus campestris, the mycelia were extracted with hot water. Purification of the extract was carried out by ethanol precipitation and by ion exchange chromatography using DEAE-Sephadex A-50. Each fraction obtained during the purification procedure was examined for antitumor activity against sarcoma 180 in ICR mice. The antitumor fraction C was isolated. It showed 56.1% inhibition ratio at a dose of 20 mg/kg/day and consisted of a polysaccharide moiety (45%) and a protein moiety (18%). The polysaccharide was analyzed by G.L.C. and found to contain mannose (42.0%), glucose (25.5%), xylose (16.6%), fucose and galactose. The protein moiety was composed of 17 amino acids. The antitumor fraction A showed immunopotentiating activity by accumulating peritoneal macrophages and by increasing plaque-forming cells in mice.

• The Korean Journal of Mycology
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• v.20 no.4
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• pp.324-336
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• 1992

On the five interspecific protoplast fusants of Ganoderma lucidum and G. applanatum was the antitumor test performed. The fusant F-2 was selected, to examine the cultured mycelia (protein bound polysaccharide) as antitumor components. When a dose of 20 mg/kg/day of each components purifed from F-2 fusant was, i.p., injected into ICR mice, the inhibition ratio of Fr. II against the solid form of sarcoma 180 increased to 1.5 times as compared with that of their parents. When Fr. II was examined for immunopotentiation activity, it increased the amount of the superoxide anion in activated macrophages to 1.2 times and the count of hemolytic plaque forming cells in the spleen to 4.3 times as compared with that of each control group. Its chemical analysis showed 85.2% polysaccharide which consisted of glucose, galactose, mannose, fucose and xylose, and 0.39% protein of 15 amino acids. The content of hexosamine was 0.39% and the molecular weight of Fr. V was $5.6{\times}10^4$ dalton.

• Journal of Applied Biological Chemistry
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• v.63 no.1
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• pp.1-8
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• 2020

This study investigated the processing characteristics of soybean (HaePum) sprouts based on temperature (5, 15 and room temperature), period (0, 6 and 12 mon) and relative humidity (20, 40, 60, and 80%) during storage. The initial germination rate of soybean sprouts was 76.02±6.32%, which significantly reduced to 57.18±8.51%, and 0% as the storage temperature of soybean increased for a period of 12 mon. The germination rate of soybean sprouts with 30 ℃ and 80% RH decreased after 4 mon of storage to 4.94%. The yellowness of cotyledon of soybean sprouts was not significantly changed during the 12 mon period of storage at 5 ℃, whereas, soybean sprouts stored at 15 ℃ and room temperature demonstrated decreased yellowness. However, the stress of cotyledon decreased with an increase in both storage temperature and time, and the hardness of hypocotyl decreased with an increase of storage time. The stress of cotyledon affected by high temperature (30 ℃) and humidity (80%) during 4 mon was reduced to 44.39±9.38 g/㎟. The asparagine content of soybean sprouts showed a similar result with the germination rate due to the amount of hypocotyl. Therefore, lower temperatures and shorter storage times are suitable for soybean sprout processing. The first order kinetic model and Arrhenius equation (activation energy =29.56 kJ/mol) were able to predict the yield of sprout at various storage temperatures and periods.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.504-508
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• 1996

This study was performed to investigate the browning intensity and electron donating ability of browning material in perilla oils from seeds roasted at 150~21$0^{\circ}C$ for 10~30 min. It was also investigated the oxidative stability of the blended perilla oil on the basis of sensory property and oxidative stability. The browning intensity in perilla oil increased with the roasting temperature and time increased. The browning intensity of perilla oil from seed roasted at 21$0^{\circ}C$ for 30 min indicated 13 times higher than that of perilla oil from seed at 15$0^{\circ}C$ for 10 min. Electron donating ability on DPPH of browning materials presented in perilla oils increased with the roasting temperature and time increased. The electron donating ability of browning materials in perilla oil from seed reasted at 21$0^{\circ}C$ for 30 min indicated 3 times higher than those of perilla oil from seed at 15$0^{\circ}C$ for 10 min. In conclusion, for the improvement of oxidative stability of perilla oil, perilla seed should be roasted at 21$0^{\circ}C$ for 30 min. These results suggest that browning materials formed between sugars and amino acids attribute to improve quality of oil such as sensory properties and oxidative stabilities. For the improvement of sensory property and oxidative stability of oil, perilla oil from seed roasted at 19$0^{\circ}C$ for 20 min was blended with the oil from seed roasted at 21$0^{\circ}C$ for 30 min as ratio of 85 : 15.

• Journal of Life Science
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• v.8 no.6
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• pp.702-710
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• 1998

The perillas were cultivated to investigate for the small metal ion effect on the harvest of perilla loaves in aquicul-ture system in the constant flow rate. The perillas were und-ergrown at the condition of low concentration of KNO$_3$and NH$_4$ H$_2$ PO$_4$as below 270ppm and 152ppm respectively. The high concentration of the metal and non-metal ca-tions of $Ca^{2+}$, $K^+,NH^{4+},Mn^{2+},Zn^{2+},Cu^{2+},Na^+,Mo^{+6}$ are influenced to the growth of plant length of perillas at the earlier time. The low concentration of the metal cations of $Ca^{2+}, K^+, NH^{4+}, NO_3^-, H_2PO_4^-$ are influenced to lower growth of perillas. The concentration of the cations of $Ca^{2+}, K^+$and $NH_4^+$ and the anions of $NO_3^-$and $H_2PO_4^-$ are affected the growth of leaf length and width of leaf of perillas. The spectoscopic analytical results showed that the perillas were growing rapidly in the period of 6 days from June 7 to June 12 by high amount of $Mg^{2+}$ ion with accumulation inside perillas. The crude protein, the crude fat and the hydrocarbon are accumulated in the leaves of perillas by binding the inorganic with amino acids to provide the nutritions needed for growth of perillas.

• Korean Journal of Food Science and Technology
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• v.13 no.3
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• pp.181-187
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• 1981

The changes in the chemical composition of yeast extracts during autolysis and their effect to the sensory quality were studied with baker's yeast, Saccharomyces cerevisiae. The amounts of extracted solids, proteins, amio-N. amino acids, especially glutamic acid, alanine and lysine, increased by the autolysis time up to 48 hrs. The results of sensory evaluation made by the multiple paired comparision test and Duncan's test indicated a significant difference is taste by the time of autolysis. In the profile test, the flavor character notes expressed by the panel were 17 different characters, 11 in aroma and 6 in taste. The character notes and the intensity of flavor changed with the time of autolysis. The sharp and beany flavor of the extracts which was autolyzed for 4 hours turned into meaty and worty flavor by 48 hours of autolysis. A proper arrangement of the flavor characters in the quantitative descriptive chart could provide a weighted value of the flavor grade. The aroma grade index and the taste grade index correlated to the amplitudes of the profile test.