• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.197-205
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• 1981

Penicillin amidase of Bacillus megaterium was recovered from the fermentation broth by adsorption on celite and immobilized by entrapping the adsorbed enzyme in acrylamide gel. The operational stability in column reactor was greatly increased by entrappment as compared with that of without entrappment. The optimum pH of the immobilized enzyme was 8.7 with broader activity profile than that of the free enzyme, while the most stable pH range appeared to be between pH 7.5 and 8.0. The optimum temperature was shifted to 5$0^{\circ}C$ from 45$^{\circ}C$ for the soluble enzyme. The values of Km and the inhibition constants for 6-APA( $K_{ia}$ ) and phenylacetic acid ( $K_{ip}$ ), were 4.55 mM, 36.5mM, and 10.5mM, respectively. No significant internal pore diffusion limitation was found since the value of effectiveness factor was 0.95. The operational half life in a column reactor at pH 8.0 was 6.8 days at 4$0^{\circ}C$ and 47 days at 3$0^{\circ}C$, whereas that of without entrappment was only 1 day and 4 days, respectively. The performance of a batch and a column reactor was also discussed with respect to the productivity. The results demonstrated that the entrappment of an adsorbed enzyme for the enhancement of the operational stability of the immobilized enzyme was useful especially when an extracellular enzyme was used.

• KSBB Journal
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• v.5 no.2
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• pp.141-149
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• 1990

$\beta$-glucosidase derived from Aspergillus niger was immobilized by (1) covalent linkage on chitin and chitosan with glutaraldehyde, (2) adsorption on DEAE-cellulose and Amberite IRA93 after succinylation, and (3) entrapment on alginate and polyacrylamide gels with various cross linking agents. The retention yield of $\beta$-glucosidase immobilized on chitosan was 31.5% and operational stability was 69% after continuous operation at column reactor(5$0^{\circ}C$ at pH 4.8) for 15 days. The retention yield and operational stability were 24.7% and 60% respectively, in adsorption on Amberite IRA 93. On the other hand, the entrapment method by alginate and polyacrylamide gel was identified to be not appropriate due to the continuous elution of inlmobilized $\beta$-glucosidase. Optimum conditions for the immobilization on chitosan were also studied with optimum pH of 4.8 and glutaraldehyde concentration of 0.4%(w/v). The properties and stability of immobilized $\beta$-glucosidase are also investigted. The conversion yield of cellobiose to glucose was also analyzed using the column type enzyme reactor to evaluate the effectiveness of immobilized enzyme.

• Journal of Life Science
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• v.13 no.3
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• pp.308-313
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• 2003

The collagenase gene from Vibrio parahaemolyticus 04 was subcloned into an expression vector pET-29b. The recombinant collagenase was expressed in Escherichia coli BL2l(DE3) and partially purified by Hi-Trap affinity and Sephacryl S-100 size exclusion chromatographies. The recombinant enzyme was purified by 43.7-fold and the yield was 73%. SDS-PAGE revealed that the molecular weight of the enzyme was approximately 35 kDa. Substrate specificity study of the enzyme displayed that the enzyme showed the highest activity with the type I collagen and the synthetic peptide, Z-GPGGPA, indicating that the enzyme was indeed a collagenase. The enzyme showed broad pH optimum around pH 6-12 and was stable between pH 5.5 and 11.5. The optimum temperature for the type I collagen degradation was $35^{\circ}C$. The thermostability measurement of the enzyme indicated that the enzyme was stable up to $55^{\circ}C$, but the activity was diminished quickly above $60^{\circ}C.$

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.768-774
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• 2017

Horseradish peroxidase (HRP) catalyzes the oxidation of aromatic compounds by hydrogen peroxide via insoluble polymer formation, which can be precipitated from the wastewater. For HRP immobilization, poly(lactic-co-glycolic acid) (PLGA) fine carrier supports were produced by using the Nano Spray Dryer B-90. Immobilized HRP was used to remove the persistent 2,4-dichlorophenol from model wastewater. Both extracted (9-16 U/g) and purified HRP (11-25 U/g) retained their activity to a high extent after crosslinking to the PLGA particles. The immobilized enzyme activity was substantially higher in both the acidic and the alkaline pH regions compared with the free enzyme. Optimally, 98% of the 2,4-dichlorophenol could be eliminated using immobilized HRP due to catalytic removal and partly to adsorption on the carrier supports. Immobilized enzyme kinetics for 2,4-dichlorophenol elimination was studied for the first time, and it could be concluded that competitive product inhibition took place.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.341-346
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• 2011

To study the effects of salinity-sodicity on bacterial population and enzyme activities, soil samples were collected from the Bay of Yellow Sea, Incheon, South Korea. In the soils nearest to the coastline, pH, electrical conductivity ($EC_e$), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were greater than the criteria of saline-sodic soil, and soils collected from sites 1.5-2 km away from the coastline were not substantially affected by the intrusion and spray of seawater. Halotolerant bacteria showed similar trends, whereas non-tolerant bacteria and enzymatic activities had opposite trends. Significant positive correlations were found between EC, exchangeable $Na^+$, and pH with SAR and ESP. In contrast, $EC_e$, SAR, ESP, and exchangeable $Na^+$ exhibited significant negative correlations with bacterial populations and enzyme activities. The results of this study indicate that the soil chemical variables related with salinity-sodicity are significantly related with the sampling distance from the coastline and are the key stress factors, which greatly affect microbial and biochemical properties.

• KSBB Journal
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• v.9 no.5
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• pp.499-505
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• 1994

Bacillus macerans cyclodextrin glucanotransferase(EC 2.4.1.19: 1, 4-${\alpha}$-D(1, 4-${\alpha}$-glucano)-transferase, CGTase) was purified by the technique of starch adsorption and DEAE-cellulose column chromatography. The molecular weight of the enzyme was 67,000, consisting of a subunit. The enzyme converted starch into ${\alpha}$-, ${\beta}$-, and ${\gamma}$-CD in the relative amounts of 1:1.68:0.32, respectively. In the early reaction period, maltohexose was formed mainly by the coupling reaction of ${\alpha}$-CD with D-glucose and then other oligosaccharides. Maltotetrose was formed mainly from ${\alpha}$-CD in the initial stage of hydrolysis of the enzyme and then small amount of other oligosaccharides. Maltotriose was a good substrate for the enzyme and maltosyl or D-glucopyranosyl group can be transfered from this sugar. In this work, D-glutosyl transfer was premiered.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.2
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• pp.128-135
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• 2005

Mixed-mode hydrophobic/ionic matrices exhibit a salt-tolerant property for adsorbing target protein from high-ionic strength feedstock, which allows the application of undiluted feedstock via an expanded bed process. In the present work, a new type of mixed-mode adsorbent designed for expanded bed adsorption, Fastline $PRO^{\circledR}$, was challenged for the capture of nattokinase from the high ionic fermentation broth of Bacillus subtilis. Two important factors, pH and ion concentration, were investigated with regard to the performance of nattokinase ad-sorption. Under initial fermentation broth conditions (pH 6.6 and conductivity of 10 mS/cm) the adsorption capacity of nattokinase with Fastline PRO was high, with a maximum capacity of 5,350 U/mL adsorbent. The elution behaviors were investigated using packed bed adsorption experiments, which demonstrated that the effective desorption of nattokinase could be achieved by effecting a pH of 9.5. The biomass pulse response experiments were carried out in order to evaluate the biomass/adsorbent interactions between Bacillus subtilis cells and Fastline PRO, and to demonstrate a stable expanded bed in the feedstock containing Bacillus subtilis cells. Finally, an EBA process, utilizing mixed-mode Fastline PRO adsorbent, was optimized to capture nattokinase directly from the fermentation broth. The purification factor reached 12.3, thereby demonstrating the advantages of the mixed-mode EBA in enzyme separation.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.828-836
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• 2015

Based on its α-amylase activity at pH 5.0 and optimal pH of the crude enzyme, a strain (named B-5) with acid α-amylase production was screened. The B-5 strain was identified as Bacillus amyloliquefaciens through morphological, physiological, and biochemical characteristics analysis, as well as 16S rDNA phylogenetic analysis. Its α-amylase gene of GenBank Accession No. GU318401 was cloned and expressed in Escherichia coli. The purified recombinant α-amylase AMY-Ba showed the optimal pH of 5.0, and was stable at a pH range of 4.0-6.0. When hydrolyzing soluble starch, amylose, and amylopectin, AMY-Ba released glucose and maltose as major end products. The α-amylase AMY-Ba in this work was different from the well-investigated J01542-type α-amylase which also came from B. amyloliquefaciens. AMY-Ba exhibited notable adsorption and hydrolysis ability towards various raw starches. Structure analysis of AMY-Ba suggested the presence of a new starch-binding domain at its C-terminal region.

• International Journal of Industrial Entomology and Biomaterials
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• v.44 no.2
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• pp.29-36
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• 2022

Over the past decades, silk sericin (SS) received increasing attention in the academic and industrial fields. In nature, SS acts as a glue that holds the two strands of silk fibrils together. However, recent works suggest that SS might have a more diverse role during the silk spinning process, such as stabilizing the SF in the silk gland. On the other hand, the sericulture industry has been trying to find novel applications for SS discarded from the silk fabric manufacturing process. Recovery and refining of SS would be the first step of the recycling of SS. Using a proper solvent SS could be shaped into various forms, such as spherical beads, microparticles, fibers, and films. Moreover, the applicability of these SS materials has been investigated in various fields such as cosmetics, templates for nanomaterials, drug delivery, heavy metal adsorption, and enzyme immobilization.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.142-145
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• 2004

Anion-exchange porous hollow-fiber membranes with a thickness of about 1.2 mm and a pore size of about $0.30{\mu}m$ were used as a supporting matrix to immobilize cycloisomaltooligosaccharide glucanotransferase (CITase). CITase was immobilized to the membrane via anion-exchange adsorption and by subsequent enzymatic cross-linking with transglutaminase, the amount of which ranged from 3 to 110 mg per g of the membrane. The degree of enzyme multilayer binding was equivalent to 0.3 to 9.8. Dextran, as the substrate, was converted into seven- to nine-glucose-membered cycloisomaltooligosaccharides (CI-7, -8, and -9) at a maxi mum yield of $28\%$ in weight at a space velocity of 10 per hour during the permeation of $2.0(w/w)\%$ dextran solution across the CITase-immobilized porous hollow-fiber membrane.