• Korean Journal of Microbiology
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• v.54 no.2
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• pp.140-145
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• 2018

The most energy-intensive processes in lipids extraction were the disruption of the cell wall of microalgae. Here, we tried to extract lipids through lysis using virus-infecting microalgae, to compare with those by the other two methods using microwave or ultrasonication. The lipids yield using viral infection was not significantly different from those using ultrasonication and microwave oven. This suggests that the same amount of lipids can be obtained with low energy and costs, as well as that microalgal lipids extraction by chlorella virus infection might provide the price competitiveness in biodiesel production even if it will be applied to mass production facilities.

• Membrane Journal
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• v.33 no.6
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• pp.390-397
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• 2023

Conventional extraction methods for polyhydroxybutyrate (PHB), a sustainable alternative to petroleum-based plastics, cause a decrease in molecular weight and a change in properties. In this work, we developed a method to extract PHB accumulated in microorganisms by physical disruption through filtration using a spiked carbon nanotube (CNT) membrane with functionalized CNT. In addition, filtration of the PHB-containing microbial solution was performed to confirm PHB extraction, which was found to be 4% more efficient than chloroform, the most used extraction method. These results indicate that the spiked CNT membrane has potential in the bioplastics recovery process.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.206.2-207
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• 2003

The immunostimulatory and host resistance effects of the Platycodon grandiflorum A. DC, changkil (CK) and inulin (CKI) isolated from CK were investigated in rats. SD rat were exposed to CK or CKI by gavages for 7days and isolated peritoneal macrophages and splenocyte were used for these studies. CK and CKI significantly enhanced peritoneal macrophages activities such as ROS production and phargocytosis. (omitted)

• Natural Product Sciences
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• v.4 no.3
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• pp.136-142
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• 1998

Atratoxin $B_1$ which was found to inhibit the growth of Candida albicans caused structural and morphological alteration of the cells. Increased accumulation of vesicles and membranous bodies in the cytoplasm, and alterations of the cell membrane and cell wall were most obvious. Sequential lytic events of the cells eventually resulted in complete disintegration of the cytoplasmic structures. These results suggested that atratoxin $B_1$ functioned by either blocking the biosynthetic step during cell wall synthesis, altering cell wall metabolism or dissolution of the cell organelles. These changes caused a progressive destruction of the cell wall leading to cell lysis.

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.89-94
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• 2001

Recently, single cell gel electrophoresis, also known as comet assay, is widely used for the detection and measurement of DNA strand breaks in vitro and in vivo in many toxicological fields such as radiation exposure, human monitoring and toxicity evaluation. As well defined, comet assay is a sensitive, rapid and visual method for the detection of DNA strand breaks in individual cells. Briefly, a small number of damaged cells suspended in a thin agarose gel on a microscope slide were lysed, unwinded, electrophoresed, and stained with a fluorescent DNA binding dye. The electric current pulled the charged DNA from the nucleus such that relaxed and broken DNA fragments migrated further. The resulting images which were subsequently named for their appearance as comets, were measured to determine the extent of DNA damages. However, some variations could be occurred in procedures, laboratories's conditions and kind of cells used. Hence, to overcome and to harmonize these matters in comet assay, International Workshop on Genotoxicity Test Procedure (IWGTP) was held with several topics including comet assay at Washington D.C. on March, 1999. In spite of some consensus in procedures and conditions in IWGTP, there are some problems still remained to be solved. In this respect, we attempted to set the practical optimal conditions in the experimental procedures such as lysis, unwinding, electrophoresis and neutralization conditions and so on. First of all, we determined optimal lysis and unwinding time by using 150 $\mu$M methyl methanesulfonate (MMS) which is usually used concentration. And then, we determined optimal positive control concentrations of benzo(a)pyrene (BaP) and MMS in the presence and absence of S9 metabolic activation system, respectively.

• Korean Journal of Microbiology
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• v.21 no.3
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• pp.115-126
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• 1983

The results that the effect of 6 detergents on the structural changes and biochemical composition of bacterial membrane of Escherichia coli and Bacillus cereus are as follows ; 1. Population growth of the bacteria was increased in case of the treatment with palmitoyl carnitine and sodium deoxy cholate but was increased in case of the treatment with palmitoyl carnitine and sodium deoxy cholate but was decreased by sodium dodecyl sulfate and palmitoyl choline, in E.coli and was decreased by palmitoyl carnitine and palmitoyl choline at the low concentration, in B. cereus. 2. The electron micrograph showed that cell wall lysis or cell collapse were observed in the treatment of sodium dodecyl sulfate and palmitoyl choline, and also cell wall was condensed by triton X-100 and sodium deoxy cholate, in E.coli. And in B. cereus, endospore formation of the bacteria was stimulated by palmitoyl choline, and cell lysis or structural changes of the membrane were observed in the treatment of sodium dodecyl sulfate, sodium cholate, and triton X-100, respectively. 3. As to the effect of detergent on the biochemical composition of biomembrane, the content of carnitine, in E.coli, and B.cereus, the content of structural protein and phospholipid were decreased by treatment of sodium dodecyl sulfate and structural protein was denatured by palmitoyl choline. 4. The profile of membrane protein revealed that the bacterial membrane were composed of various proteins. By dint of this result, some of membrane proteins were solubilized or changed to small molecules by the treatment of sodium dodecyl sulfate and palmitoyl choline, in E.coli and membrane protein of the biomembrane by treatment of sodium dodecyl sulfate, sodium deoxy cholate, palmitoyl choline, and palmitoyl carnitine were confirmed to be different profile as compared with those of the control, in B. cereus. Therefore, it is suggested that sodium dfodecyl sulfate and palmitoyl choline soulbilized biomembranes or inhibited membrane transport and that palmitoyl carnitine and sodium deoxy cholate were used as an energy source or stimulating the membrane transport, in E.coli. And, it is suggested that all of detergents were inhibited biomembrane synthesis, expet saponin, in B.cereus.

• KSBB Journal
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• v.13 no.6
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• pp.700-705
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• 1998

Studies were made to investigate effects of the scale-up of stirred tank bioreactors on cell growth and alkaloids production for suspension cultures of Eschscholtzia californica. In the 1.5 L STR, cell lysis was observed at 110 rpm or higher agitation speed. The agitation speed of 30 L STR was 43.7 rpm to maintain the same shear stress developed in 1.5 L STR of 100 rpm. As a result of scale-up from 1.5 L to 30 L STR, the specific growth rate was decreased from 0.12 to 0.07 day-1. The alkaloids productivity was also decreased from 0.24 to 0.14 mg/L-day. Changes of mixing performance and oxygen transfer were studied to explain the decrease of cell growth and alkaloids production. Decreased oxygen transfer rate coefficient(KLa) and increased mixing time by the scale-up was observed at various aeration rates.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.1-6
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• 1994

Many useful biomaterials like enzymes are contained in yeast cells. However, the release of these intracellular biomateriais from the cells is required to recover them with hot water, solvent or various cell breakage methods of mechanical or non mechanical ones. The cell lysis or breakage of yeast is usually made by solvent like ethyl acetate and mechanical disintrgration with high pressure homogenizer or agitating beads mill. The separation of cell debris (i.e. solid liquid separation) is done by centrifuge or membrane depending on the recovery conditions. The features of both separation methods are shown in Tables 1 and 2. As it is often difficult to obtain a clear supernatant by centrifuge from the suspension containing cell debris, the membrane separation is also often used to gel a clear supernatant. In this report we introduce the several applications of membrane separation to separate the cell debris of yeast disintegrated chemically or mechanically and to recover the intracellular biomaterials.

• Tuberculosis and Respiratory Diseases
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• v.40 no.3
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• pp.213-222
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• 1993

Background : Bronchial asthma has been known as an inflmmatory disease. There have been many evidences that polymorphonuclear leukocytes (PMN) might play an important role in the pathogrnesis of asthma. Although many investigators suggested that pneumocyte injury by PMN-derived oxygen radicals may contribute to the pathogenesis of asthma, there has been few report for a direct evidence of oxygen radicals-mediated pneumocyte injury in bronchial asthma. Furthermore the exact mechanism of oxygen radicals-mediated pneumocyte injury is still controversy. This study was designed to establish a direct in vitro evidence and its clinical significance of pneumocyte injury by PMN-derived superoxide anion in bronchial asthma and to elucidate the main mechanism of superoxide anion-mediated pneumocyte injury. Methods : 12 stable asthmatics and 5 healthy volunteers were participated in this study. PMN was separated from peripheral venous blood samples by using dextran sedimentation and Ficoll-Hypaque density gradient separation method. Superoxide anion productions by PMN and plasma SOD activities were measured by spectrophotometric assay using the principle of SOD inhibitable cytochrome c reduction. PMN-mediated pneumocyte injuries were measured by $^{51}Cr$-release assay using A549 pneumocytes and were expressed as percent lysis and percent detachment. Results: 1) PMN from asthmatics produced more amount of superoxide anion compared to PMN from normal subjects ($6.65{\pm}0.58$ vs $2.81{\pm}0.95\;nmol/1{\times}10^6$ cells, p<0.05), and showed an inverse correlation with $FEV_1$(R=-0.63, p<0.05), but no correlation with $PC_{20}$ histamine in asthmatics. 2) Plasma SOD activities were decreased in asthmatics compared to normal subjects but not significant, and showed a positive correlation with $FEV_1$(R=0.63, p<0.05) but no correlation with $PC_{20}$ histamine in asthmatics. 3) There were a positive correlation between plasma SOD activity and superoxide anion production by PMN in normal subjects (R=0.88, p<0.05) but not in asthmatics. 4) PMN-mediated pneumocyte injury was predominantly expressed as cell detachment rather than cell lysis in both groups, and PMN from asthmatics showed more potent cytotoxic effect on A549 pneumocytes compated to PMN from normal subjects. PMN-mediated detachment rather than lysis of A549 pneumocytes was significantly inhibited by in vitro SOD but not by diluted serum. 5) PMN-mediated detachment rather than lysis of A549 pneumocytes showed a good correlation with superoxide anion production by PMN (R=0.90 in normal subjects, R=0.82 in asthmatics, p<0.05) but no correlation with plasma SOD activity. PMN-mediated pneumocyte injuries were not correlated with $FEV_1$ or $PC_{20}$ histamine in asthmatics. 6) There were no significant differences in PMN-mediated pneumocyte injuries between allergic and nonallergic asthmatics. Conclusion : Our results suggest that pneumocyte injury by PMN-derived superoxide anion may partially contribute to the pathogenesis of asthma and that cell detachment rather than cell lysis may be the mechanism of superoxide anion-mediated pneumocyte injury.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1628-1634
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• 1999

The polymerase chain reaction (PCR) for the sensitive and specific detection of Listeria monocytogenes was employed by using LM 1 and LM 2 primers which were based on the listeriolysin O gene. The direct use of cell suspension as DNA template, without DNA extraction or lysis step, was suitable and specific enough to detect L. monocytogenes at the level of $10^2$ CFU or less per PCR for the pure culture and milk sample, however, the detection sensitivity became blunt for other food samples such as kimchi and chicken. The nested PCR, in which L-1 and L-2 (both designed from listeriolysin O gene) were employed as inner primers, was specific for detecting L. monocytogenes and enhanced the detection limit by 10 times. The PCR using LM 1 and LM 2 primers was very effective to detect L. monocytogenes from foods in terms of the specificity and time consumed, i. e. within $4{\sim}8\;hrs$ (nested PCR).