• Korean Journal of Food Science and Technology
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• v.12 no.1
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• pp.45-52
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• 1980

The nylon (poly 6, 10) microcapsules containing ${\beta}-galactosidase$ were obtained by the interfacial polymerization of 1, 6-diaminohexane and sebacoyl chloride with ${\beta}-galactosidase$ from Escherichia coli. They were generally spherical and had a mean diameter of $80{\mu}$ with 45 % of the activity recovery. In particular, there was no transport hamper of lactose through the membrane of microcapsules. The characteristics of the microencapsulated enzyme were similar to those of soluble enzyme optimal pHs, $7.0{\sim}7.2$ for the soluble and $7.3{\sim}7.5$ for the microencapsulated ; optimal temperatures, $50^{\circ}C$ for both ; apparent $K_m,\;3.33{\times}10^{-4}(on ONPG),$ $2.86{\times}10^{-3}$ M(on lactose) for the soluble and $5.28{\times}10^{-4}$ (on ONPG), $4.25{\times}10^{-3}$ M (on lactose) for the microencapsulated ; activation energies, 8.94 for the soluble and 9.78 Kcal/mole for the microencapsulated enzyme. Using this microencapsulated ${\beta}-galactosidase$, hydrolyses of lactose and milk lactose were carried out and 80 % of 5 % lactose solution and 70 % of lactose in skim milk were hydrolyzed in 40 hr at $27^{\circ}C$. The reusability and operational stability showed that the remaining activity was 50 % of the original activity after 5 runs and 120 hr of total operating time at $27^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.33 no.4
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• pp.281-287
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• 2005

The endoinulinase gene (inu, 2.733 kb, EC 3.2.1.7) from Paenibacillus polymyxa was subcloned into an Escherichia coli-yeast shuttle vector with GALl promoter for the expression in Saccharomyces cerevisiae. The constructed plasmid, pYGENIU27 (8.6 kb) was introduced into S. cerevisiae SEY2102 cell and then the yeast transformant was selected on the synthetic defined media lacking uracil and on the inulin-containing media. The recombinant endoinulinase was predominantly localized in the periplasmic space of the yeast cell. The total activity of the endoinulinase reached 1.81 unit/ml by cultivation of yeast transformant on YPDG medium. The optimized conditions determined for the inulooligosaccharides (IOSs) production from inulin were as follows; pH, 8.0; reaction temperature, $45^{\circ}C$; inulin source, Jerusalem artichoke. Enzyme activity was stably maintained up to the pH of 10.0. Under the optimized condition and with endoinulinase of 36 unit/g-inulin, IOSs started to be produced after 10 min of enzymatic reaction. By the reaction with inulin, IOSs consisting of inulobiose (F2), inulotriose (F3), and inulotetraose (F4) were produced and F3 was the major product. Consequently, these data would be used as a fundamental parameters for the production of functional sweetener IOSs from inulin by recombinant yeast endoinulinase.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.606-612
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• 2018

The enzyme xylose isomerase (E.C. 5.3.1.5, XI) is responsible for the conversion of an aldose to ketose, especially xylose to xylulose. Owing to the ability of XI to isomerize glucose to fructose, this enzyme is used in the food industry to prepare high-fructose corn syrup. Therefore, we studied the characteristics of XI from Anoxybacillus kamchatkensis G10, a thermophilic bacterium. First, the gene coding for XI (xylA) was inserted into the pET-21a(+) expression vector and the construct was transformed into the Escherichia coli competent cell BL21 (DE3). The expression of recombinant XI was induced in the absence of isopropyl-thio-${\beta}$-galactopyranoside and purified using Ni-NTA affinity chromatography. The optimum temperature of recombinant XI was $80^{\circ}C$ and measurement of the heat stability indicated that 55% of residual activity was maintained after 2 h incubation at $60^{\circ}C$. The optimum pH was found to be 7.5 in sodium phosphate buffer. Magnesium, manganese, and cobalt ions were found to increase the enzyme activity; manganese was the most effective. Additionally, recombinant XI was resistant to the presence of $Ca^{2+}$ and $Zn^{2+}$ ions. The kinetic properties, $K_m$ and $V_{max}$, were calculated as 81.44 mM and $2.237{\mu}mol/min/mg$, respectively. Through redundancy analysis, XI of A. kamchatkensis G10 was classified into a family containing type II XIs produced by the genera Geobacillus, Bacillus, and Thermotoga. These results suggested that the thermostable nature of XI of A. kamchatkensis G10 may be advantageous in industrial applications and food processing.

• Journal of Plant Biology
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• v.38 no.1
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• pp.87-93
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• 1995

For understanding physiological nature of phototaxis in Synechocystis sp. PCC 6803 PTX(S. 6803 PTX), we examined the effects of some metabolic inhibitors and cation ionophore on the phototactic movement. In the presence of DCMU, which blocks the photosynthetic electron transport just after photosystem II acceptor, there was no inhibitory effect on the phototaxis up to $100\;\mu\textrm{M}$. Instead, the respiratory electron chain inhibitor such as sodium azide dramatically impaired the phototaxis in S. 6803 PTX. These observations indicate that the phototaxis is linked not to photo-phosphorylation, but to respiratory phosphorylation. When the cells were treated with un couplers such as CCCP or DNP, which dissipate the electrochemical gradient of proton($\Delta\mu_{H}+$) across the cytoplasmic membrane, these chemicals did not affect phototaxis. In contrast, when cells were treated with DCCD or NBD which deprive cells of A TP but leave $\Delta\mu_{H}+$ intact across the membrane, the phototactic movement was severly reduced. These results imply that ATP production, not proton motive force, is involved in the phototactic movement in this organism as a driving motive force. The application of specific calcium ionophore A23187 strongly impaired positive phototaxis. Calcium fluxes should be engaged in the sensory trans-duction of phototactic orientation. Finally, when ethionine was supplimented to culture media, the photomovement of this organism was inhibited. This implies that methylation/demethylation mechanism controls the process of phototaxis in S. 6803 PTX like chemotaxis in E. coli and Salmonella typhimurium.murium.

• Journal of Life Science
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• v.25 no.7
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• pp.748-756
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• 2015

The report explores the possibility that the single extract of natural substances and the mixture of single extracts of natural substances create a synergy effect to increase the antimicrobial activity. It also compares the previous researches to find out if the natural medicinal herbs’ extract has antimicrobial activity on dandruff causative organism, Malassezia furfur. For the experiment on the mixture of single extracts of natural substances, the results are like following: 1. Staphylococcus aures’s antibacterial activity is resistant to mixture of three natural substances. 2. Escherichia coil’s antibacterial activity is resistant to mixture with Coptidis rhizoma. 3. Candida albicans’ antifungal activity is resistant to mixture with Chinese galls, which means the different results may be expected when tested with each germ. 4. On the other hand, Malassezia furfur has no antifungal activity on the single extract of natural substances and shows weak antifungal activity, whose diameter is 3.20 mm when tested with the mixture of 50% of Coptidis rhizoma and 50% of Phytoncide. The result is totally different from the one on the same eumycetes, C. albicans. That is because M. furfur has more lipophilic chemicaled cell walls than C. albicans does and it also consists of lamella layer, inner plasma membrane and intermediate multiple layers.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.270-277
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• 2010

In order to manufacture Bacillus cereus-free fermented soybean products, an antimicrobial agentproducing isolate against B. cereus was obtained from 150 traditionally fermented soybean products. The morphological and biochemical tests and the phylogenetic relationship among 16S rRNA gene sequences indicated that the isolate named as the strain SCK 121057 was most closely related to Bacillus licheniformis. The B. licheniformis isolate began to produce the antimicrobial agent after 48 h of incubation. The agent was nonproteinaceous and insensitive to heat, long term storage and protease K. Electron microscopic observation indicated that the agent attacked the membrane of B. cereus, leaving the ghost cell. The isolate inhibited growth of B. subtilis, Lactobacillus brevis and various types of pathogenic strains including Escherichia coli, E. faecalis, Micrococcus luteus, Staphylococcus aureus, Aspergillus flavus, A. ochraceus, and A. parasiticus as well as B. cereus. After coinoculation of B. licheniformis SCK 121057 and B. cereus in the ratio (as the basis of CFU/g sample) of 10 to 1 on the surface of cooked soybeans, cell numbers of B. cereus had been dramatically reduced after 31 days of incubation compared to those of single inoculation of B. cereus.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1720-1728
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• 2020

We have previously characterized AprESJ4, the major fibrinolytic enzyme from Bacillus subtilis SJ4 (Yao et al., 2019). During that study, we observed a 68 kDa protein with fibrinolytic activity. In this study, we cloned the gene (vprSJ4) encoding the 68 kDa protein, a mature Vpr and minor protease secreted by Bacillus species. vprSJ4 encodes a preproenzyme consisting of 810 amino acids (aa) including signal sequence (28 aa) and prosequence (132 aa). The mature enzyme (650 aa) has a predicted molecular weight of 68,467.35. Unlike Vprs from other B. subtilis strains, VprSJ4 has 4 additional amino acids (DEFA) at the C-terminus. vprSJ4 was overexpressed in Escherichia coli. PreproVprSJ4 was localized in inclusion bodies, and subjected to in vitro renaturation and purification by an affinity column. SDS-PAGE and western blot showed that autoprocessing of preproVprSJ4 occurred and 68 kDa and smaller proteins were produced. The optimum pH and temperature of the recombinant VprSJ4 were pH 7.0 and 40℃, respectively. Kinetic parameters of recombinant VprSJ4 were measured by using an artificial substrate, N-succinyl-ala-ala-pro-phe-p-nitroanilide. Coexpression of vprSJ4 and aprESJ4 using pHY300PLK increased the fibrinolytic activity a further 117% when compared with aprESJ4 single expression using the same vector in B. subtilis WB600.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.449-455
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• 2011

This study was performed to develop antimicrobial films using polyvinyl alcohol and methyl cellulose. Methyl cellulose and polyvinyl alcohol films plasticized with PEG(polyethylene glycol) were prepared by solvent casting process under addition of 0.025~1.0 wt% ampicillin and 0.1~1.0 wt% streptomycin as an antimicrobial agent. The mechanical properties of prepared films were examined by universal testing machine(UTM). Tensile strength of methyl cellulose films was 15.44~21.70 $N/mm^2$. Tensile strength of PVA(15 wt%) film was 20.2~51.5 $N/mm^2$, and the tensile strength of the antimicrobial films were decreased linearly with increasing the antibiotic loading amount up to 1 wt%. Antimicrobial activities of PVA and methyl cellulose films containing ampicillin and streptomycin through the disc diffusion test for the Staphylococcus aureus and Escherichia coli. The antimicrobial activity of methyl cellulose films and PVA containing ampicillin were higher than that of containing streptomycin methyl cellulose films. The results indicate the films may be a proper materials for antimicrobial packing applications.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2419-2424
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• 2013

Guanosine-5'-diphosphate 3'-diphosphate (ppGpp) serves as alarmone in bacterial stringent responses. In this study, an affinity column was constructed by immobilizing ppGpp to NHS-Sepharose for isolating ppGpp-binding proteins. A novel ppGpp-binding protein, YjgA, was isolated and characterized by MALDI-TOF MS (matrix-assisted laser desorption ionization-time-of-flight mass spectrometry) coupled with two-dimensional gel electrophoresis. YjgA and truncated forms of YjgA were cloned and over-expressed in BL21 (DE3). The binding affinity of YjgA to ppGpp was determined by equilibrium dialysis. The interaction of YjgA with ppGpp was very specific, considering that the dissociation constant of YjgA with ppGpp was measured as $5.2{\pm}2.0{\mu}M$, while the affinities to GTP and GDP were about 60 and 30 times weaker than ppGpp. Expression of yjgA gene in Escherichia coli K-12 MG1655 was examined by reverse transcription polymerase chain reaction (RT-PCR). RT-PCR results revealed that yjgA was expressed from early to late stationary phase. The yjgA deletion mutant exhibited decreased cell number at stationary phase compared to parent strain and the over-expression of YjgA increased the cell number. These results suggested that YjgA might stimulate cell division under stationary phase. In most prokaryotic genome, about half of the protein candidates are hypothetical, that are expected to be expressed but there is no experimental report on their functions. The approach utilized in this study may serve as an effective mean to probe the functions of hypothetical proteins.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.23-37
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• 2022

Thirty-six weaned piglets with an initial body weight (BW) of 8.43 ± 0.40 kg (28 days of age, ([Landrace × Yorkshire] × Duroc) were randomly assigned to 6 treatments for a 2-week feeding trial to determine the effects of different inorganic zinc (IZ), organic zinc (OZ) or combination of low crude protein diet (LP) and Mixed feed additive (MFA) on diarrhea score, nutrient digestibility, zinc utilization, blood profiles, organ weight, and fecal microflora in weaned piglet diet. The pigs were individually placed in 45 × 55 × 45 cm stainless steel metabolism cages in an environmentally controlled room (30 ± 1℃). The dietary treatments included a negative control (NC), positive control (PC; zinc oxide, 1,000 mg/kg), T1 (IZ : OZ, 850 : 150), T2 (IZ : OZ 700 : 300), T3 (IZ : OZ, 500 : 500), and T4 (LP + MFA [0.1% Essential oils + 0.08% Protease + 0.02% Xylanase]). The daily feed allowance was adjusted to 2.7 times the maintenance requirement for digestible energy (2.7 × 110 kcal of DE/kg BW^0.75). This allowance was divided into two equal parts, and the piglets were fed at 08 : 30 and 17 : 30 each day. Water was provided ad libitum through a drinking nipple. The diarrhea score was significantly increased (p < 0.05) in NC treatment compared with other treatments. The apparent total tract digestibility (ATTD) of dry matter (DM), nitrogen (N), and gross energy (GE) was significantly increased (p < 0.05) in the T2 treatment compared with the PC and NC treatments in week 1. In week 2, the ATTD of DM, N, and GE was significantly decreased (p < 0.05) in the NC treatment compared with other treatments. The T3 treatment had significantly higher (p < 0.05) ATTD and apparent ileal digestibility of zinc than the PC and T1 treatments. The Escherichia coli count in feces was significantly decreased in the T4 treatment compared with the NC and T2 treatments. The Lactobacillus count in feces was significantly increased in the T4 and T1 treatment compared with the T2 and T3 treatments. In conclusion, IZ : OZ 500 : 500 levels could improve nutrient digestibility and zinc utilization in weaned piglets, Moreover, MFA in LP diets could be used as a zinc alternative.