• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.63-72
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• 1998

In order to evaluate the biodegradability and mechanism of 4,5,6-trichloroguaiacol (TCG) produced from bleaching process in pulp mill by Phanerochaete chrysosporium, Trametes versicolor, and Inonotus cuticularis, changes in TCG and its metabolites during biodegradation were analyzed by HPLC, and GC/MS spectrometry. By three fungi, the maximum biodegradability against TCG were very quickly reached, compared with other chlorinated aromatic compounds such as PCP. Within 24 hrs, T versicolor indicated up to 95% of TCG removal rate, and P. chrysosporium and I. cuticularis also showed more than 80%, and 90%, respectively. Particularly, in case of T. versicolor, the removal rate of TCG after 1 hr. incubation was reached to approximately 90%, implying very rapid metabolization of TCG. However, by analyzing the filtrates extracted from TCG containing culture by GC/MS, the major metabolites at initial stage of biodegradation were dimers, indicating that the added TCG monomers were quickly polymerized. The others were trichloroveratrole, dichloroguaiacol, and trichlorobenzoic acid, suggesting that TCG may be biodegraded by several sequential reactions such as polymerization, oxidation, methylation, dechlorination, and hydroxylation. In other experiments, the extracellular fluid which did not contain any fungal mycelia was used to evaluate the effect of mycelia on TCG biodegradation. The extracellular fluid of T. versicolor also biodegraded TCG up to 90% within 24hrs, but those of P. chrysosporium and I. cuticularis did not show any good biodegradability. T versicolor showed the highest value of laccase, and other two fungi indicated a little activity of lignin peroxidase (LiP) and manganese peroxidase (MnP). In addition, the laccase activity of T. versicolor was very linearly proportional to the removal rate of TCG during incubation, in other words, showing the induction effect against TCG. Consequently, the biodegradation of TCG was very dependent upon the activity of laccase.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.534-544
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• 2014

The effects of microbial iron reduction and oxidation on the immobilization and mobilization of copper were investigated in a high concentration of sulfate with synthesized Fe(III) minerals and red earth soils rich in amorphous Fe (hydr)oxides. Batch microcosm experiments showed that red earth soil inoculated with subsurface sediments had a faster Fe(III) bioreduction rate than pure amorphous Fe(III) minerals and resulted in quicker immobilization of Cu in the aqueous fraction. Coinciding with the decrease of aqueous Cu, $SO_4{^{2-}}$ in the inoculated red earth soil decreased acutely after incubation. The shift in the microbial community composite in the inoculated soil was analyzed through denaturing gradient gel electrophoresis. Results revealed the potential cooperative effect of microbial Fe(III) reduction and sulfate reduction on copper immobilization. After exposure to air for 144 h, more than 50% of the immobilized Cu was remobilized from the anaerobic matrices; aqueous sulfate increased significantly. Sequential extraction analysis demonstrated that the organic matter/sulfide-bound Cu increased by 52% after anaerobic incubation relative to the abiotic treatment but decreased by 32% after oxidation, indicating the generation and oxidation of Cu-sulfide coprecipitates in the inoculated red earth soil. These findings suggest that the immobilization of copper could be enhanced by mediating microbial Fe(III) reduction with sulfate reduction under anaerobic conditions. The findings have an important implication for bioremediation in Cu-contaminated and Fe-rich soils, especially in acid-mine-drainage-affected sites.

• Journal of Microbiology and Biotechnology
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• v.34 no.5
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• pp.1017-1028
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• 2024

Lignocellulolytic enzymes play a crucial role in efficiently converting lignocellulose into valuable platform molecules in various industries. However, they are limited by their production yields, costs, and stability. Consequently, their production by producers adapted to local environments and the choice of low-cost raw materials can address these limitations. Due to the large amounts of olive stones (OS) generated in Morocco which are still undervalued, Penicillium crustosum, Fusarium nygamai, Trichoderma capillare, and Aspergillus calidoustus, are cultivated under different fermentation techniques using this by-product as a local lignocellulosic substrate. Based on a multilevel factorial design, their potential to produce lignocellulolytic enzymes during 15 days of dark incubation was evaluated. The results revealed that P. crustosum expressed a maximum total cellulase activity of 10.9 IU/ml under sequential fermentation (SF) and 3.6 IU/ml of β-glucosidase activity under submerged fermentation (SmF). F. nygamai recorded the best laccase activity of 9 IU/ml under solid-state fermentation (SSF). Unlike T. capillare, SF was the inducive culture for the former activity with 7.6 IU/ml. A. calidoustus produced, respectively, 1,009 ㎍/ml of proteins and 11.5 IU/ml of endoglucanase activity as the best results achieved. Optimum cellulase production took place after the 5th day under SF, while ligninases occurred between the 9th and the 11th days under SSF. This study reports for the first time the lignocellulolytic activities of F. nygamai and A. calidoustus. Furthermore, it underlines the potential of the four fungi as biomass decomposers for environmentally-friendly applications, emphasizing the efficiency of OS as an inducing substrate for enzyme production.

• Plant Biotechnology Reports
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• v.2 no.3
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• pp.171-177
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• 2008

This paper reports an improved protocol for isolation, culture and regeneration of Lotus corniculatus protoplasts. A range of parameters which influence the isolation of L. corniculatus protoplasts were investigated, i.e., enzyme combination, tissue type, incubation period and osmolarity level. Of three enzyme combinations tested, the highest yield of viable protoplasts was achieved with the combination of 2% Cellulase Onozuka RS, 1% Macerozyme R-10, 0.5% Driselase and 0.2% Pectolyase. The use of etiolated cotyledon tissue as a source for protoplast isolation proved vital in obtaining substantially higher protoplast yields than previously reported. Culture of the protoplasts on a nitrocellulose membrane with a Lolium perenne feeder-layer on the sequential series of PEL medium was highly successful in the formation of microcolonies with plating efficiencies 3-10 times greater than previous studies. Shoot regeneration and intact plants were achieved from 46% of protoplast-derived cell colonies.

• Electrical & Electronic Materials
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• v.28 no.2
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• pp.25-33
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• 2015

Ruthenium (Ru) thin films were grown on thermally-grown $SiO_2$ substrates by atomic layer deposition (ALD) using a sequential supply of four kinds of novel zero-valent Ru precursors, isopropyl-methylbenzene-cyclohexadiene Ru(0) (IMBCHDRu, $C_{16}H_{22}Ru$), ethylbenzen-cyclohexadiene Ru(0) (EBCHDRu, $C_{14}H_{18}Ru$), ethylbenzen-ethyl-cyclohexadiene Ru(0) (EBECHDRu, $C_{16}H_{22}Ru$), and (ethylbenzene)(1,3-butadiene)Ru(0) (EBBDRu, $C_{12}H_{16}Ru$) and molecular oxygen (O2) as a reactant at substrate temperatures ranging from 140 to $350^{\circ}C$. It was shown that little incubation cycles were observed for ALD-Ru processes using these new novel zero-valent Ru precursors, indicating of the improved nucleation as compared to the use of typical higher-valent Ru precursors such as cyclopentadienyl-based Ru (II) or ${\beta}$-diketonate Ru (III) metallorganic precursors. It was also shown that Ru nuclei were formed after very short cycles (only 3 ALD cycles) and the maximum nuclei densities were almost 2 order of magnitude higher than that obtained using higher-valent Ru precursors. The step coverage of ALD-Ru was excellent, around 100% at on a hole-type contact with an ultra-high aspect ratio (~32) and ultra-small trench with an aspect ratio of ~ 4.5 (top-opening diameter: ~ 25 nm). The developed ALD-Ru film was successfully used as a seed layer for Cu electroplating.

• Journal of the Korean Electrochemical Society
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• v.25 no.1
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• pp.13-21
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• 2022

There is an increasing interest in monitoring of specific biomarker for determining progression of a disease or efficacy of a treatment. Conventional method for quantification of specific biomarkers as enzyme linked immunosorbent assay (ELISA) has high material costs, long incubation periods, requires large volume of samples and involves special instruments, which necessitates clinical samples to be sent to a lab. This paper reports on the development of an electrochemical biosensor to measure total immunoglobulin E (IgE), a marker of asthma disease that varies with age, gender, and disease in concentrations from 0.3-1000 ng/mL with consuming 20 µL volume of whole blood sample. The sensor provides rapid, accurate, easy, point-of-care measurement of IgE, also, sequential monitoring of total IgE with ovalbumin (OVA) induced mice is another application of sensor. Taken together, these results provide an alternative way for detection of biomarkers in whole blood with low volumes and long-term ex-vivo assessments for understanding the progression of a disease.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.517-521
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• 1988

This study focused on the psychrotrophic post-pasteurization contamination of fluid milk pro-ducts which were processed by HTST system. Pasteurized line samples and container samples of each fluid milk product (whole milk and skim milk) were taken in a large fluid milk plant. tine samples were collected through nine and five different sampling locations for whole milk and skim milk products, respectively. Each sample was subjected to preliminary incubation (PI) at 21$^{\circ}C$ for 16h followed by standard plate count (SPC) and crystal violet tetrazolium agar count (CVT). Flavor, SPC, and psychrotrophic bacteria count (PBC) were determined after 7 d at 7.2$^{\circ}C$. In addition, ten sequential container samples (packaged in 1000ml paperboard containers) were taken from a filler at the beginning of each product run. These samples were used for PI followed by SPC and CVT. In addition, flavor evaluations, SPC and PBC tests were conducted after 7,10, and 14 d at 7.2$^{\circ}C$. The mean PI-CVT values for the line samples showed differences depending on the location. There was major contamination between pasteurized storage tank and the filler. The PI-CVT counts for each container sample were negatively correlated with flayer scores at 10 and 140. There were good correlations among PI-CVT values of line samples and the percentage of total container samples with acceptable flavor after 10d.

• The Journal of the Korean Society for Microbiology
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• v.35 no.4
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• pp.273-282
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• 2000

dTDP-rhamnose provides L-rhamnose to the bridge-like structure between mycolyl arabinogalactan and peptidoglycan of the mycobacterial cell wall. dTDP-rhamnose is composed of glucose-l-phosphate and dTTP by four enzymes encoded by rmlA-D. To determine the region(s) of RmlC protein essential for its dTDP-4-keto-6-deoxyglucose epimerase activity, we overexpressed both whole (202 amino acids) and three different truncated (N-terminal 106 or 150 or C-terminal 97 amino acids) RmlC proteins of Mycobacterium tuberculosis. The RmlC enzyme activity in the soluble lysates of ${\Delta}rmlC$ E. coli strain $S{\Phi}874$ (DE3 PlysS) expressing the wild type or truncated rmlC genes was initially analyzed by three sequential reactions from dTDP-glucose to dTDP-rhamnose in the presence of purified RmlB and RmlD. All three soluble lysates containing the truncated RmlC proteins showed no enzyme activity, while that containing the wild type RmlC was active. This wild type RmlC was then overexpressed and purified. The incubation of the purified RmlC enzyme so obtained with dTDP-4-keto-6-deoxyglucose resulted in the conversion of dTDP-4-keto-rhamnose. The results show that the truncated regions of the RmlC protein are important for the RmlC enzyme activity in M. tuberculosis.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.628-636
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• 2012

Raw-starch-digesting enzyme (RSDA) was immobilized on Amberlite beads by conjugation of glutaraldehyde/polyglutaraldehyde (PG)-activated beads or by crosslinking. The effect of immobilization on enzyme stability and catalytic efficiency was evaluated. Immobilization conditions greatly influenced the immobilization efficiency. Optimum pH values shifted from pH 5 to 6 for spontaneous crosslinking and sequential crosslinking, to pH 6-8 for RSDA covalently attached on polyglutaraldehyde-activated Amberlite beads, and to pH 7 for RSDA on glutaraldehyde-activated Amberlite. RSDA on glutaraldehyde-activated Amberlite beads had no loss of activity after 2 h storage at pH 9; enzyme on PG-activated beads lost 9%, whereas soluble enzyme lost 65% of its initial activity. Soluble enzyme lost 50% initial activity after 3 h incubation at $60^{\circ}C$, whereas glutaraldehyde-activated derivative lost only 7.7% initial activity. RSDA derivatives retained over 90% activity after 10 batch reuse at $40^{\circ}C$. The apparent $K_m$ of the enzyme reduced from 0.35 mg/ml to 0.32 mg/ml for RSDA on glutaraldehyde-activated RSDA but increased to 0.42 mg/ml for the PG-activated RSDA derivative. Covalent immobilization on glutaraldehyde Amberlite beads was most stable and promises to address the instability and contamination issues that impede the industrial use of RSDAs. Moreover, the cheap, porous, and non-toxic nature of Amberlite, ease of immobilization, and high yield make it more interesting for the immobilization of this enzyme.

• Journal of Soil and Groundwater Environment
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• v.20 no.2
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• pp.47-54
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• 2015

The objective of this study was to optimize the experimental conditions for bioleaching of arsenic (As) using Herbaspirillum sp. GW103 and to understand the interaction between bacteria and As during bioleaching. Five variables, temperature, time, CaCO₃, coconut oil cake, and shaking rate, were optimized using response surface methodology (RSM) based Box-Behnken design (BBD). Maximum (73.2%) bioleaching of As was observed at 30℃, 60 h incubation, 1.75% CaCO₃, 3% coconut oil cake, and 140 rpm. Sequential extraction of bioleached soil revealed that the isolate Herbaspirillum sp. GW103 significantly reduced 28.6% of water soluble fraction and increased 38.8% of the carbonate fraction. The results of the study indicate that the diazotrophic bacteria Herbaspirillum sp. could be used for bioleaching As from mine soil.