• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.406-411
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• 2008

This study was conducted to examine the quality enhancement of fermented soybean pastes (cheonggukjang) using microorganisms with high enzyme activities and proper experimental design. The microorganisms for soybean paste fermentation were selected from a specific area of Gyeonggi and were idenlified by 16S rDNA sequence analysis. To prepare the cheonggukjang, an optimum mixing ratio of selected microorganisms was determined using contour plots and numerical optimization methods. A total of 39 microorganisms were isolated from the soybean paste, consisting primarily of Bacillus subtilis and Bacillus licheniformis, and no mold was found. Three microorganisms showing high enzyme activities were selected and used to formulate an optimum mixing ratio for cheonggukjang preparation. Based on levels of amino-nitrogen, ammonium-nitrogen, antioxidant activity values, and sensory preference results, the optimum mixing ratio of 50% of Bacillus sp. SC-1 and 50% SC-3 was suggested for the manufacture of high quality of cheonggukjang.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1153-1160
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• 2009

Lactosucrose ($4^G-\beta$-D-galactosylsucrose) is an oligosaccharide consisting of galactose, glucose, and fructose. In this study, we prepared lactosucrose from lactose and sucrose using a levansucrase derived from Zymomonas mobilis. Optimum conditions for lactosucrose formation were $23^{\circ}C$, pH 7.0, 18.0% (w/v) lactose monohydrate, and 18% (w/v) sucrose as substrates, and 1 unit of enzyme/ml of reaction mixture. Under these conditions, the lactosucrose conversion efficiency was 28.5%. The product was purified and confirmed to be O-$\beta$-D-galactopyranosyl-($1{\rightarrow}4$)-O-$\beta$)-D-glucopyranosyl-($1{\rightarrow}2$)-$\beta$-D-fructofuranoside, or lactosucrose. A mixed-enzyme system containing a levansucrase and a glucose oxidase was applied in order to increase the efficiency of lactose and sucrose conversion to lactosucrose, which rose to 43.2% as a result.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.284-292
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• 2018

A novel ${\beta}$-agarase, AgaJ5, was identified from an agar-degrading marine bacterium, Gayadomonas joobiniege G7. It belongs to the glycoside hydrolase family 86 and is composed of 805 amino acids with a 30-amino-acid signal peptide. Zymogram analysis showed that purified AgaJ5 has agarase activity. The optimum temperature and pH for AgaJ5 activity were determined to be $30^{\circ}C$ and 4.5, respectively. AgaJ5 was an acidic ${\beta}$-agarase that had strong activity at a narrow pH range of 4.5-5.5, and was a cold-adapted enzyme, retaining 40% of enzymatic activity at $10^{\circ}C$. AgaJ5 required monovalent ions such as $Na^+$ and $K^+$ for its maximum activity, but its activity was severely inhibited by several metal ions. The $K_m$ and $V_{max}$ of AgaJ5 for agarose were 8.9 mg/ml and 188.6 U/mg, respectively. Notably, thin-layer chromatography, mass spectrometry, and agarose-liquefication analyses revealed that AgaJ5 was an endo-type ${\beta}$-agarase producing neoagarohexaose as the final main product of agarose hydrolysis. Therefore, these results suggest that AgaJ5 from G. joobiniege G7 is a novel endo-type neoagarohexaose-producing ${\beta}$-agarase having specific biochemical features that may be useful for industrial applications.

• Mycobiology
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• v.46 no.4
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• pp.382-387
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• 2018

The entomopathogenic fungus Cordyceps militaris is a valuable medicinal ascomycete, which degenerates frequently during subsequent culture. To avoid economic losses during industrialized production, scratching stimuli of mycelia was introduced to improve the fruiting body production. The present results indicated that higher yields and biological efficiency were obtained from two degenerate strains (YN1-14 and YN2-7) but not from g38 (an insertional mutant in Rhf1 gene with higher yields and shorter growth periods). Furthermore, the growth periods of the fruiting bodies were at least 5 days earlier when the mycelia were scratched before stromata differentiation. Three ROS-scavenging genes including Cu/Zn superoxide dismutase (CmSod1), Glutathione peroxidase (CmGpx), and Catalase A (CmCat A) were isolated and their expression profiles against scratching were determined in degenerate strain YN1-14 and mutant strain g38. At day 5 after scratching, the expression level of CmGpx significantly decreased for strain g38, but that of CmSod1 significantly increased for YN1-14. These results indicated that scratching is an effective way to promote fruiting body production of degenerate strain, which may be related at least with Rhf1 and active oxygen scavenging genes.

• Journal of Animal Science and Technology
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• v.49 no.5
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• pp.667-676
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• 2007

This study was conducted to determine effects of cellulolytic microbes inoculation to sawdust-based spent mushroom substrate(SMS) during deepstacking on fermentation parameters, total microbial counts and cellulolytic enzyme activity and to on SMS nutrients utilization by sheep. For sheep metabolism trials, six sheep(ram, average 54.8kg) were fed a Control diet(70% concentrates, 15% rice straw and 15% SMS with no microbial treatment on a dry basis) and a Treatment diet(the same diet including SMS with a microbial treatment) for 2 trials. Spent mushroom substrates with or without a microbial(4 strains including 1 strain of Enterobacter ludwigii, 1 strain of Bacillus cereus and 2 strains of Bacillus subtillis) treatment (1% of SMS on wet basis) were deepstacked for 7 days. The internal temperatures in 1.2 M/T of SMS deepstacks reached to 50±5℃ within 7 days of storage. Total microbial counts remarkably decreased (P<0.05) with a deepstacking process and were not affected(P>0.05) by the microbial treatment. For fibrolytic enzyme activity, CMCase and xylanase activities were decreased(P<0.05) by a deepstacking process. After deepstacking, the microbial treatment showed about 2.5-times higher(P<0.05) for CMCase activity and about 4-times higher(P<0.05) for xylanase activity than those of the Control. Activities of ligninolytic enzymes such as laccase and MnP were not affected by the microbial treatment. The sheep fed the microbially treated SMS diet had a tendency of greater total tract digestibilities of ash(P=0.051), NFE (P=0.071), hemicellulose(P=0.087) and NDF(P=0.096) than those fed the untreated SMS diet. Nitrogen balance of sheep was not affected(P>0.05) by feeding of microbially treated SMS. Accordingly, these results indicate that cellulolytic microbes inoculation during deepstacking of SMS may improve the bio- utilization of SMS by sheep.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.2
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• pp.248-256
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• 2003

Two experiments were conducted to determine the effects of expander processing and enzyme supplementation of wheat-based diets on growth performance and nutrient digestibility in finishing pigs. For Exp. 1, 60 finishing pigs (average initial BW of 49.5 kg) were fed meal, standard pellets and expanded pellets in a 70 d growth assay. From 49.5 to 79.0 kg, 79.0 to 111.8 kg, and overall (49.5 to 111.8 kg), ADG and ADFI were not affected by pelleting or standard vs expander conditioning (p>0.22). However, from 49.5 to 79.0 kg, pigs fed pellets have greater gain/feed than pigs fed mash (p<0.04), and pigs fed expanded pellets tended to have greater (p<0.10) gain/feed than pigs fed standard pellets. Overall (i.e. from 49.5 to 111.8 kg), gain/feed (p<0.02) and apparent fecal digestibilities of DM (p<0.001) and N (p<0.02) were improved by pelleting the diets. Also, expander processing further improved gain/feed (p<0.06) and digestibility of DM (p<0.04) compared to standard steam conditioning. Scores for keratinization (p<0.002) and ulceration (p<0.003) of the stomach were increased by pelleting, but the mean scores for the various treatments ranged only from 0.05 to 1.08 (i.e., low to mild keratosis and ulceration). For Exp. 2, 80 pigs (average initial BW of 54.1 kg) were fed mash and pellets (standard or expander) without and with xylanase. The enzyme was added to supply 4,000 units of xylanase activity/kg of diet. Adding xylanase to the mash diet improved gain/feed from 90.7 to 115.9 kg (p<0.04) of the growth assay and digestibility of DM (p<0.05) on d 39. However, in pelleted diets, adding the enzyme did not improve growth performance or digestibility of nutrients. Pelleting tended to increase scores for ulceration (p<0.06), and enzyme supplementation decreased stomach keratinization scores for pigs fed the standard pellets (p<0.01). However, as in Exp. 1, the mean scores for all treatment groups were quiet low (i.e., ranging from normal to mild). In conclusion, pelleting improved efficiency of growth, but additional benefits from expander conditioning were observed only in Exp. 1. Finally, xylanase tended to improve growth performance and nutrient digestibility, only in pigs fed mash diets but not in pigs fed pellets.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.9-14
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• 2010

In this study, lactic acid bacteria with high angiotensin converting enzyme inhibitor activity were isolated from Korean fermented food, such as kimchi and salted seafood. The strain HLJ59, isolated from salted shrimp showed the highest angiotensin converting enzyme inhibitor activity in DeMan Rogosa Sharpe broth. Optimum growth temperature of Lactobacillus brevis HLJ59 was at $34^{\circ}C$. Acid treatment at pH 3.0 for 1.5 h decreased cell viability from $9.9{\times}10^8$ CFU/ml to $3.11{\times}10^4$ CFU/ml. The bile extract concentration of 0.3%, 0.5%, and 1.0% in MRS broth did not inhibit the growth of HLJ59. Isolated strain HLJ59 showed more sensibility to amikacin, gentamycin, neomycin, streptomycin, kanamycin, cefmetazole, cephalothin, ampicillin, ticarcillin, sulbactam+ampicillin, amoxicillin+clavulanic acid (AMC), tetracycline, and sulfamethoxazole+trime thoprim (SXT) as compare to other 7 different antibiotics. However, it showed more resistance to cefoxatin, ceftnaxone, penicillin, ciprofloxacin, nalidixic acid, lincomycin, and chloramphenicol.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.584-592
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• 2004

A thermostable $\beta$-glycosidase gene, tfi $\beta$-gly, was cloned from the genomic library of Thermus filiformis Wai33 A1. ifi $\beta$-gly consists of 1,296 bp nucleotide sequence and encodes a polypeptide of 431 amino acids. It shares a strong amino acid sequence similarity with the $\beta$-glycosidases from other Thermus spp. belonging to the glycosyl hydrolase family 1. In the present study, the enzyme was overexpressed in Escherichia coli BL21 (DE3) using the pET21b(+) vector system. The recombinant enzyme was purified to homogeneity by heat treatment and a $Ni^{2+}$-affinity chromatography. Polyacrylamide gel electrophoresis (PAGE) showed that the recombinant Tfi $\beta$-glycosidase was a monomeric form with molecular mass of 49 kDa. The temperature and pH range for optimal activity of the purified enzyme were 80- $90^{\circ}C$ and 5.0-6.0, respectively. Ninety-three percent of the enzyme activity was remained at $70^{\circ}C$ after 12 h, and its half-life at $80^{\circ}C$ was 6 h, indicating that Tfi $\beta$-glycosidase is highly thermostable. Based on its K_m$, or $K_{cat}K_m$, ratio, Tfi $\beta$-glycosidase appeared to have higher affinity for $\beta$-D-glucoside than for $\beta$-D-galactoside, however, $K_{cat} for \beta$-D-galactoside was much higher than that for $\beta$-D-glucoside. The activity for lactose hydrolysis was proportionally increased at $70^{\circ}C$ and pH 7.0 without substrate inhibition until reaching 250 mM lactose concentration. The specific activity of Tfi TEX>$\beta$-glycosidase on 138 mM lactose at $70{^\circ}C$ and pH 7.0 was 134.9 U/mg. Consequently, this newly cloned enzyme appears to have a valuable advantage of conducting biotechnological processes at elevated temperature during milk pasteurization in the production of low-lactose milk.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.12
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• pp.1632-1638
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• 2010

Two experiments with growing pigs were conducted to investigate the effects of two distinct multienzyme preparations on nutrient digestibility, growth performance and blood profiles. In Exp. 1, a total of 96 pigs ($29.7{\pm}0.69\;kg$) were utilized in a 42-day performance and digestibility trial using four dietary treatments: CON (control diet), ENDO (control+0.10% Endopower), NSPase1 (control+0.10% NSPase) and NSPase2 (control+0.20% NSPase). Endopower was a commercial multienzyme preparation which contained ${\alpha}$-galactosidase, galactomannase, xylanase and ${\beta}$-glucanase. NSPase mainly contained ${\alpha}$-1,6-${\beta}$-galactosidase, ${\beta}$-1,4-mannanase and ${\beta}$-1,4-mannosidase. There were six replication pens per treatment with four pigs per pen. Pigs fed NSPase1 diet had a higher ADG (p<0.05) and G:F (p<0.05) than those fed the control diet. There were no significant differences in growth performance among the multienzyme treatments (p>0.05). Compared with CON, apparent digestibility of DM was increased (p<0.05) by ENDO treatment. N digestibility was improved (p<0.05) in response to multienzyme treatments during the experimental period. Blood urea nitrogen (BUN) was higher (p<0.05) in ENDO treatment than in CON and NSPase1 treatments at the end of the experiment, while the glucose level improved (p<0.05) due to ENDO and NSPase2 treatments. In Exp. 2, four ileal-cannulated, growing barrows ($20.17{\pm}1.31\;kg$) were housed in individual metabolism crates and randomly assigned to 1of 4 treatments (same as Exp. 1) within a $4{\times}4$ Latin square design. Enzyme supplementations improved the majority of apparent ileal amino acid digestibilities (p<0.05). It is concluded that the supplementation of NSPase1 improved growth performance as well as N digestibility and partially improved apparent ileal amino acid digestibility in growing pigs fed a diet based on corn and soybean meal.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.1
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• pp.30-33
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• 2015

Enzymatic modification of proteins is often used to increase the biological activity of materials. Silkworm powder has been investigated as a functional food resource, but no study has been performed on its modification by commercial food enzyme. Therefore, this study aimed to determine the feasibility of such modification of silkworm powder by alkaline protease. The activity of the enzyme was confirmed using an azocasein assay. Subsequently the silkworm powder was hydrolyzed by enzymatic treatment. UV visible spectrometry showed that the supernatant of silkworm powder subjected to enzymatic treatment had a stronger absorption band than the untreated powder. SDS-PAGE electrophoresis showed that the molecular weight of silkworm powder decreased on enzymatic treatment. Thus the results indicate that commercial enzymes might be used to modify the characteristics of silkworm powder.