• Journal of Applied Biological Chemistry
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• v.51 no.6
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• pp.272-276
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• 2008

Purification and some properties of Xylogone sphaerospora ${\beta}$-mannanase were reprevious previous paper. Locust bean gum galactomannan was hydrolyzed by the purified ${\beta}$-mannanase, and then the hydrolysates was separated by activated carbon column chromatography. The main hydrolysates were composed of D.P. (Degree of Polymerization) 4 and 6 galactosyl mannooligosaccharides. For elucidate the structure of D.P 4 and 6 galactosyl mannooligosaccharides, sequential enzymatic action was performed. D.P 4 and 6 were identified as ${Gal^2}{Man_3}\;(6^2-mono-O-{\alpha}-D-galactopyranosyl-4-O-{\beta}-D-mannotriose)$ and ${Gal^2}{Man_5}\;(6^2-mono-O-{\alpha}-D-galacto- pyranosyl-4-O-{\beta}-D-mannopentaose)$. To investigate the effects of locust bean gum galactosyl mannooligosaccharides on in vitro growth of Bifidobacterium longum, B. bifidum, B. infantis, B. adolescentis, B. animalis, B. auglutum and B. breve. Bifidobacterium spp. were cultivated individually on the modified-MRS medium containing carbon source such as D.P. 4 and D.P. 6 galactosyl mannooligosaccharides, respectively. B. longum and B. bifidum grew up to-fold and 6.6-fold more effectively by the treatment of D.P. 6 galactosyl mannooligosaccharides, compared to those of standard MRS medium. Especially, D.P. 6 was more effective than D.P. 4 galactosyl mannooligosaccharide on the growth of Bifidobacterium spp.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.97-104
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• 2004

Effects of sub-materials such as, ethanol, mustard, and chitosan, on enzymatic, microbial and physicochemical characteristics of kochujang were investigated during fermentation. Activity of ${\alpha}$-amylase was low in chitosan-added kochujang, whereas those of ${\beta}$-amylase and pretense did not show any remarkable difference. Viable cells of yeast and bacteria decreased in sub-material-added kochujang during fermentation, with yeast counts decreasing more rapidly in ethanol- and mustard-added kochujang than that with chitosan. Consistency of kochujang decreased during fermentation, with the highest consistency observed in ethanol-added kochujang. Oxidation-reduction potential was low in chitosan-added kochujang. Water activity of all kochujang groups decreased during fermentation with the lowest in ethanol-added kochujang. Hunter L-, a-, and b-values of chitosan-added kochujang were higher than other groups, whereas increase in total color difference of low-salt without sub-material group was lowest pH of kochujang was the highest in ethanol-added kochujang, whereas titratable acidity increased remarkably in chitosan-added group. Total sugar and reducing sugar contents of kochujang were high in ethanol-and mustard-added groups, whereas ethanol production decreased remarkably in mustard-added kochujang. Amino nitrogen content was highest in low-salt without sub-material kochujang during late aging period. Ammonia nitrogen content was lower in mustard-added kochujang. After 12 weeks of fermentation, ethanol-added kochujang was more acceptable than mustard-and chitosan-added groups in taste, color, and overall acceptabilities.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.9-18
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• 2016

Two Bacillus strains, CJW15 and SSD8, with strong antibacterial activities were isolated from cheonggukjang. Both were identified as B. amyloliquefaciens strains after gene sequencing of rRNA and recA. CJW15 strongly inhibited the growth of B. cereus (ATCC14579), Listeria monocytogenes (ATCC19111), and Lactococcus lactis (ATCC11454). In comparison, SSD8 inhibited the growth of B. cereus (ATCC14579) and Enterococcus faecium (ATCC19953). The antibacterial activities of the two strains were not affected when exposed to a temperature of $100^{\circ}C$ for 15 min and were quite stable in acidic (pH 3) and alkaline (pH 12) pH conditions. Enzymatic treatments (trypsin, pepsin, proteinase K, and protease) had no effect on the activity of CJW15, but reduced the activity of SSD8 by half. Both isolates possess genes involved in the synthesis of lipopeptides (e.g. surfactin, fengycin, iturin, and iturin A), and genes encoding subtilin, a bacteriocin. Moreover, both isolates have fibrinolytic activities as well.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.757-764
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• 2018

A cellulolytic fungus, YDJ14, was isolated from compost and identified as an Aspergillus sp. strain. Three extracellular ${\beta}$-glucosidases, BGL-A1, BGL-A2, and BGL-A3, were separated using ultrafiltration, ammonium sulfate fractionation, and High-Q chromatography. The molecular masses of the three enzymes were estimated to be 100, 45, and 40 kDa, respectively, by SDS-PAGE. The optimum pH and temperature of BGL-A3 were 5.0 and $50^{\circ}C$, respectively, whereas the optimum pH and temperature of BGL-A1 and BGL-A2 were identical (4.0 and $60^{\circ}C$, respectively). The half-life of BGL-A3 at $70^{\circ}C$ (2.8 min) was shorter than that of BGL-A1 and BGL-A2 (12.1 and 8.8 min, respectively). All three enzymes preferred p-nitrophenyl-${\beta}$-$\text\tiny{D}$-glucopyranoside (pNPG) and hardly hydrolyzed cellobiose, suggesting that these enzymes were aryl ${\beta}$-glucosidases. The $K_m$ of BGL-A3 (1.26 mM) for pNPG was much higher than that of BGL-A1 and BGL-A2 (0.25 and 0.27 mM, respectively). These results suggested that BGL-A1 and BGL-A2 were similar in their enzymatic properties, whereas BGL-A3 differed from the two enzymes. When tilianin (a flavone glycoside of acacetin) was reacted with the three enzymes, the inhibitory activity for monoamine oxidase, a target in the treatment of neurological disorders, was similar to that shown by acacetin. We conclude that these enzymes may be useful in the hydrolysis of flavone glycosides to improve their inhibitory activities.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.60-66
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• 1996

To investigate a possible application of three strains of lactic acid bacteria(strain No. 49. No. 61. No. 75) from kimchi in milk fermentation industry, the optimal condition for production of intracellular ${\beta}-galactosidase$ from Lactobacillus(L.) plantarum and its enzymatic properties were examined. The preferable carbon source of the medium for strain No. 49 in production of ${\beta}-galactosidase$ was MRS broth with 1.0% lactose instead of dextrose of pH 65. for strain No. 75 with 1.0% galactose and for strain No. 61 with 3.0% lactose at pH 7.5, respectively. The maximum enzyme production from strain No. 49, No. 75 was observed after 48 hours culture at $30^{\circ}C$ in a medium containing the appropriate carbon source, from strain No. 61 after 48 hours culture at room temperature. The optimum temperature for ${\beta}-galactosidase$ activity from L. plantarum was $60^{\circ}C$ for strain No. 49, $37^{\circ}C$ for strain No. 61 and $50^{\circ}C$ for strain No. 75, respectively. The heat stability of enzyme activities for all three strains remained 90% at $45^{\circ}C$. The optimal pH was pH 6.5 and enzyme activities were most stable at pH for all three bacteria.

• Applied Biological Chemistry
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• v.15 no.3
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• pp.199-206
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• 1972

As a study on the konjak mannan-hydrolyzing enzymes from Aspergillus awamori, the culture conditions for enzyme formation, purification and properties of the enzymes and the effect of gamma-irradiation on the enzymatic hydrolysis were investigated. The results are summarized as follows: 1) A strain of A. awamori was selected as having the highest productivity of mannanase among 81 species of molds. 2) The optimum conditions for solid culture on wheat bran were 3 days of culture period, pH 4 of spraying water and 100% addition of tap water. 3) The optimum conditions for shaking culture were 6 days of culture period, addition of 0.1% xylose plus 0.5% konjak mannan and of 0.04% peptone. 4) Konjak mannan-hydrolyzing enzymes were separated into fraction I and fraction II by ammonium sulfate fractionation and DEAE-Sephadex column chromatography. 5) Fractions I and II showed pH optima of 4, pH stability of $3.5{\sim}5$ and $3{\sim}6$ and the extent of hydrolyzing konjak mannan 9% and 50%, respectively. 6) Hydrolysis of konjak mannan by a crude enzyme preparation was partially accerelated by gamma-irradiation of substrate above 0.5 Mrad and the effect was more remarkable by irradiating in wet state than in dry state. 7) Gamma-irradiation of konjak mannan brought about the increase in reducing power and decrease in viscosity and the effect was more remarkable in wet state than in dry state.

• Journal of Applied Biological Chemistry
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• v.52 no.4
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• pp.157-162
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• 2009

An agar-liquefying bacteria (SC-22), which produces a diffusible agarase that caused agar softening around the colony was isolated from Daecheong lake in Korea. Chemotaxanomic and phylogenetic analyses based on 16S rRNA gene sequences revealed the strain was classified as Cellvibrio mixtus SC-22. The isolate SC-22 showed maximal extracellular agarase activity with 58.5 U/mL after 48 h cultivation in the presence of 0.2% agar. It was observed that the isolate produced two kinds of extracellular and three kinds of intracellular isoenzymes. The major agarase was purified from the culture filtrate of agarolytic bacteria by ammonium sulfate precipitation, anion exchange and gel filtration column chromatographic methods. The molecular mass of the purified enzyme was estimated to be 25 kDa by SDS-PAGE. The optimum pH and temperature of the purified enzyme were pH 7.0 and $50^{\circ}C$, respectively. The agarase activity was activated by $Fe^{2+}$, $Na^+$ and $Ca^{2+}$ ions while it was inhibited by $Hg^{2+}$, $Mn^{2+}$ and $Cu^{2+}$ at 1 mM concentration. The predominant hydrolysis product of agarose by the enzyme was galactose and disaccharide on TLC, indicating the cleavage of $\beta$-1,4 linkage in a random manner. The enzyme showed high substrate specificity for only agar and agarose among various polysaccharides.

• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.140-144
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• 2003

Type Ⅰ signal peptidase is an integral membrane protein that functions to cleave signal peptides from secreted and membrane proteins. The enzyme serves as a potential target for the development of novel antibacterial agents due to its unique physiological properties. Despite being one of the best characterized enzymes, the catalysis of Type Ⅰ signal peptidase still remains controversy over the catalytic serine/lysine dyad mechanism. It appears that the dyad proteases are generally less efficient than the prototypical serine/histidine/aspartic acid triad found in most enzymes, although Type Ⅰ signal peptidase is an exception to this rule. In this paper, we have proposed that Type Ⅰ signal peptidase may act as the serine/lysine/aspartic acid triad cataltytic mechanism. Therefore, the aspartic acid 99 residue in the E. coli signal peptidase was chosen and mutated to an alanine to see if there is any possible role of the aspartic acid in the catalytic function. Type Ⅰ signal peptidase D99A protein was inactive in vitro assay using the procoat synthesized by in vitro transcription translation. However, the mutant was active using a highly sensitive in vivo assay. Pulse-chase experiments show that the replacement of aspartic acid 99 with alanine results in a very unstable signal peptidase molecule. Therefore, we conclude that it is unlikely that the residue is directly involved in catalysis, but rather plays an important role in stabilizing the protein structure.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.588-596
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• 2018

An endo-${\beta}$-1,4-glucanase gene, cel9K, was cloned using the shot-gun method from Paenibacillus sp. X4, which was isolated from alpine soil. The gene was 2,994 bp in length, encoding a protein of 997 amino acid residues with a predicted signal peptide composed of 32 amino acid residues. Cel9K was a multimodular enzyme, and the molecular mass and theoretical pI of the mature Cel9K were 103.5 kDa and 4.81, respectively. Cel9K contains the GGxxDAGD, PHHR, GAxxGG, YxDDI, and EVxxDYN motifs found in most glycoside hydrolase family 9 (GH9) members. The protein sequence showed the highest similarity (88%) with the cellulase of Bacillus sp. BP23 in comparison with the enzymes with reported properties. The enzyme was purified by chromatography using HiTrap Q, CHT-II, and HiTrap Butyl HP. Using SDS-PAGE/activity staining, the molecular mass of Cel9K was estimated to be 93 kDa, which is a truncated form produced by the proteolytic cleavage of its C-terminus. Cel9K was optimally active at pH 5.5 and $50^{\circ}C$ and showed a half-life of 59.2 min at $50^{\circ}C$. The CMCase activity was increased to more than 150% in the presence of 2 mM $Na^+$, $K^+$, and $Ba^{2+}$, but decreased significantly to less than 50% by $Mn^{2+}$ and $Co^{2+}$. The addition of Cel9K to a commercial enzyme set (Celluclast 1.5L + Novozym 188) increased the saccharification of the pretreated reed and rice straw powders by 30.4% and 15.9%, respectively. The results suggest that Cel9K can be used to enhance the enzymatic conversion of lignocellulosic biomass to reducing sugars as an additive.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.1
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• pp.37-45
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• 2013

This study was conducted to improve the yield of extracts from Alaska pollock Theragra chalcogramma head and sea tangle Laminaria japonica byproducts using various commercial enzymes, such as Alcalase, Flavourzyme, Neutrase (NH), and Protamex. Among the enzymatic hydrolysates, the yield was highest in hydrolysate incubated with NH for 4 h. NH-treated hydrolysates (NHH) also improved functional properties, such as angiotensin-I converting enzyme (ACE) inhibitory activity and 2,2-diphenyl-1-picryldrazyl (DPPH) radical scavenging activity, as compared to extracts from Alaska pollock head and sea tangle byproducts. Total free amino acid and taste values of NHH were 379.7 mg/100 mL and 24.03, respectively, after digestion for 4 h. These values are 2.2-fold and 1.9-fold higher compared with those of water soluble fractions extracted from Alaska pollock head and non-forming sea tangle, respectively. According to the taste value results, the major taste-active compounds among free amino acids of NHH were glutamic acid and aspartic acid. These results suggest that NHH can be used as an ingredient for natural seasoning preparation.