• Journal of Microbiology and Biotechnology
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• v.31 no.4
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• pp.570-583
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• 2021

Pyrococcus furiosus α-amylase can hydrolyze α-1,4 linkages in starch and related carbohydrates under hyperthermophilic condition (~ 100℃), showing great potential in a wide range of industrial applications, while its relatively low productivity from heterologous hosts has limited the industrial applications. Bacillus subtilis, a gram-positive bacterium, has been widely used in industrial production for its non-pathogenic and powerful secretory characteristics. This study was conducted to increase production of P. furiosus α-amylase in B. subtilis through three strategies. Initial experiments showed that co-expression of P. furiosus molecular chaperone peptidyl-prolyl cis-trans isomerase through genomic integration mode, using a CRISPR/Cas9 system, increased soluble amylase production. Therefore, considering that native P. furiosus α-amylase is produced within a hyperthermophilic environment and is highly thermostable, heat treatment of intact culture at 90℃ for 15 min was performed, thereby greatly increasing soluble amylase production. After optimization of the culture conditions (nitrogen source, carbon source, metal ion, temperature and pH), experiments in a 3-L fermenter yielded a soluble activity of 3,806.7 U/ml, which was 3.3- and 28.2-fold those of a control without heat treatment (1,155.1 U/ml) and an empty expression vector control (135.1 U/ml), respectively. This represents the highest P. furiosus α-amylase production reported to date and should promote innovation in the starch liquefaction process and related industrial productions. Meanwhile, heat treatment, which may promote folding of aggregated P. furiosus α-amylase into a soluble, active form through the transfer of kinetic energy, may be of general benefit when producing proteins from thermophilic archaea.

• Current Research on Agriculture and Life Sciences
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• v.31 no.3
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• pp.170-176
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• 2013

In this study, we selected some material to have potential bioactivity from natural plants, confirmed as basic data for industrializing and tried to develope the food materials using them. DPPH, ABTS, antioxidant protection factor, TBARs and antimicrobial activity of extracts from Rosa multiflora Thunberg fruits were determined. The total phenolics extracted from Rosa multiflora were 12.08, 11.82, 11.1 and 12.6 mg/g when using water, 70% ethanol, 70% methanol and 70% acetone as the solvent, respectively. The optimum conditions for extracting the phenolic compounds were 70% ethanol over for 12 hrs(11.82 mg/g). The electron donating ability and inhibition rate on ABTS of the 70% ethanol extracts were 97% and 92.2%, respectively while the antioxidant protection factor(PF) of the water extracts and 70% ethanol extracts were 1.79 and 1.34 PF, respectively. The TBAR (thiobarbituric acid reactive substance) value were $1.3{\mu}M$ for the control and $0.15{\mu}M$ for the 70% ethanol extracts. The inhibitory activity against ${\alpha}$-amylase was 26% for the 70% ethanol extracts. The 70% ethanol extracts from Rosa multiflora Thunberg fruits exhibited antimicrobial activity against H. pylori, S. epidermidis, S. aureusand and E. coli with clear zone diameters of 14, 25, 14 and 13 mm, respectively when using $200{\mu}g/mL$ of the phenolic compounds. An HPLC analysis identified 6 major phenolic metabolites in the Rosa multiflora Thunberg fruits extracts: rosmarinic acid, caffeic acid, chlorogenic acid, courmaric acid, protocatechuic acid and quercetin. In particular, the content of rosmarinic acid was the highest in the 70% ethanol extracts. Therefore these results indicate that 70% ethanol extracts from Rosa multiflora Thunberg fruits can be useful as a natural antioxidant and in functional foods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.8
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• pp.957-964
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• 2008

Antioxidative, antidiabetes, antibacterial, anticancer and angiotensin-converting enzyme (ACE) inhibitory activities of methanol extracts of dried persimmon, fresh persimmon and persimmon leaves were investigated. Total polyphenol content of dried persimmon, fresh persimmon and persimmon leaves were 147.79, 301.45 and $315.90\;{\mu}g/mg$, respectively, of which fresh persimmon and persimmon leaves had significantly higher total polyphenol than dried persimmon. Activities of DPPH radical scavenging, lipid peroxidation inhibition and salivary $\alpha$-amylase inhibition were increased in persimmon leaves related to total polyphenol contents. Anticancer activities against AGS of fresh persimmon and persimmon leaves were $65{\sim}70%$; however, there were no significant differences between dried persimmon and fresh persimmon on free radical scavenging activity and inhibitory activity of salivary $\alpha$-amylase. Also, extracts of dried persimmon, fresh persimmon and persimmon leaves showed good ACE inhibitory activities. Dried persimmon and fresh persimmon showed antibacterial activities on E.coli O157:H7. Therefore, there are many difference activities by dried and parts of persimmon. From this result, it is suggested that persimmon leaves is believed to have possible antioxidative, antidiabetes and anticancer capacities by polyphenol, but further studies on the identification of the active compound(s) as antioxidant, antidiabetic, antihypertensive and antibacterial materials will be needed to develop a better understanding of its potency on persimmons.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.189-196
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• 1993

Allelopathic inhibition by substance(s) originated from sicklepod(Cassia tora L.) seed on germination of other plant seeds, was confirmed and used to elucidate general mechanism of allelopathy which was occurred widly in natural and/or agricultural ecosystems. The mechanism was deduced from changes in water contents, ${\alpha}$-amylase activities, protease activities, concentrations of abscisic acid and total phenolic compounds during germination of rice and radish seeds treated with water-soluble extracts of sicklepod seeds. The results obtained were summarized as follows. 1. The % germinations of radish, rice, lettuce, barley seeds were decreased by substances originated from crushed sicklepod seeds. 2. By the treatment of water-soluble extracts of sicklepod seeds, the inhibition of germination of radish seeds was occured with the sequential phenomena of increase of protease activity(synthesis), decrease of water content and increase of total phenolic compounds content. 3. In rice, the inhibition of seed germination by the water-slouble extracts of sicklepod seeds was related to increase of abscisic acid concentration and then decrease of ${\alpha}$-amylase activity(synthesis).

• Korean Journal of Food Science and Technology
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• v.27 no.1
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• pp.56-62
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• 1995

This study was designed to investigate the changes in microflora and enzyme activities of traditional kochujang meju during fermentation for 60 days. The pH of meju decreased continously up to 40 days of aging and then increased slightly thereafter, while the change in titratable acidity showed the opposite trend to that of pH. The viable cell count of aerobic bacteria increared gradually for up to 40 days of fermentation and then decreased slightly thereafter, while that of molds and yeasts showed a rapid increase up to 40 days of fermentation and then leveled off. ${\alpha}-amylase$ activity increased slightly for up to 40 days of meju fermentation and then stabilized. On the other hand, ${\beta}-amylase$ and glucoamylase activities did not show a significant change for up to 20 days of fermentation and then increased rapidly at 40th day of fermentation. Acidic, neutral and alkaline protease activities increased sharply up to 40 days of aging and then decreased significently at 60th day of fermentation. These results suggest that meju fermented for 40 days had the highest quality in terms of the number of microflora and enzyme activity.

• Journal of Dairy Science and Biotechnology
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• v.37 no.4
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• pp.223-236
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• 2019

This study aimed to investigate the physiological characteristics and anti-diabetic effects of Lactobacillus plantarum KI69. The α-amylase and α-glucosidase inhibitory activity of L. plantarum KI69 was 91.17±2.23% and 98.71±4.23%, respectively. The propionic, acetic, and butyric acid contents of the MRS broth inoculated with L. plantarum KI69 were 8.78±1.12 ppm, 1.34±0.07% (w/v), and 0.876±0.003 g/kg, respectively. L. plantarum KI69 showed higher sensitivity to penicillin-G, oxacillin, and chloramphenicol among 16 different antibiotics and showed the highest resistance to ampicillin and vancomycin. The strain showed higher β-galactosidase, β-glucosidase, and N-acetyl-β-glucosaminidase activities than other enzymes. Additionally, it did not produce carcinogenic enzymes, such as β-glucuronidase. The survival rate of L. plantarum KI69 in 0.3% bile was 96.42%. Moreover, the strain showed a 91.45% survival rate at pH 2.0. It was resistant to Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus with the rates of 15.44%, 50.79%, 58.62%, and 37.85%, respectively. L. plantarum (25.85%) showed higher adhesion ability than the positive control L. rhamnosus GG (20.87%). These results demonstrate that L. plantarum KI69 has a probiotic potential with anti-diabetic effects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.975-979
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• 2010

Biological activities of different parts (stems, leaves, roots, fruits) and solvents (water, ethanol) of seabuckthorn (Hippophae rhamnoides L.) grown in Korea were tested as follows. In the experiment of inhibiting $\alpha$-glucosidase activity, ethanol extract of Hippophae rhamnoides L. stem showed the highest inhibitory activity by 93% and the next highest was the ethanol extract of its leaf by 88.7%. In the case of these two extracts, the effect of inhibiting $\alpha$-glucosidase activity was extraordinarily great when comparing with control group, acarbose. In the experiment of inhibiting $\alpha$-amylase activity, water extract of leaf showed the highest result by 54.7%, among all extracts. Regarding anticancer effect for HT-29 cell and DU-145 cell, water extract of root showed 47.1% and 32.3% activities, respectively. The experiment on antibacterial activity showed that the ethanol extract from the leaf inhibitory activity of Clostridium butyricum, Proteus mirabilis, and Shigella flexneri which are the several food borne pathogenic strains. In future research, materials for biological activity appear isolated and purified and research should continue.

• Preventive Nutrition and Food Science
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• v.9 no.3
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• pp.199-205
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• 2004

The effect of chitosan on enzymatic activities and on bioactive compounds was characterized during germination at $25^{\circ}C$ for 7 days to search for a method to produce a germinated black rice. The germination rate was reduced by the addition of lactate and chitosan. The rotting rate was greatly decreased by chitosan, suggesting that the addition of chitosan into a germination solution might be an effective method for controlling fungal contamination during the germination of cereals. The addition of 100 and 200 ppm chitosan increased $\alpha$-amylase activity after 7 days by up to 152 % and 197 %, respectively. The activities of $\beta$-amylase and $\beta$-glucosidase were lower with 200 ppm chitosan than in distilled water and 100 ppm lactate. The amount of total soluble phenolics and total flavonoids decreased rapidly for four days and thereafter remained constant until the seventh day. The antioxidant activity of germinated black rice, in terms of hydrogen-donating activity, increased slowly and did not correspond to the changes of total soluble phenolics and total flavonoids. The amount of phytic acid was reduced by the addition of 200 ppm chitosan compared to distilled water, indicating that chitosan could be used as an elicitor for the increase of phytase activity during the germination of black rice.

• Applied Biological Chemistry
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• v.11
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• pp.131-136
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• 1969

For the study of the effects of low gamma-irradiation on malt enrymes, barley seeds were irradiated by Co-60, with 10, 100, 1,000 and 10,000 rads respectively. The experiments on the germinated green malt were resulted as follows. (1) By the low doses below 1,000 rads the fresh weights of green malts increased but at the hgih doses of 10,000 rads they decreased. (2) In all doses ${\alpha}$-amylase activity and saccharifying ability were expedited, showing the increased effects of 23-69% and 87-178% respectively and their peaks at 100 rads. (3) Protease activity showed almost no changes ein the low doses below 1,000 rads and decreased remarkably at the high doses of 10,000 rads. (4) Reducing sugar contents of green malts were decreased, particularly in 100 and 1,000 rads. (5) Soluble protein contents of green malts were increased in all doses and had their highest value at 100 rads.

• Food Science and Preservation
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• v.22 no.2
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• pp.182-189
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• 2015

Four different kinds of coffee beans (CS, Colombia supremo; EY, Ethiopia yirgacheffee; IM, Indonesia mandheling; and IMM, India monsooned malabar) were roasted at 200 and $250^{\circ}C$ for 10, 15, and 20 min. To determine the optimum roasting conditions, various components of the coffee beans such as pyrazines produced during the roasting, and their antioxidant and antidiabetic effects were analyzed. The different roasting condition did not affect on the concentration of caffeine. However, the amount of 5-caffeoylquinic acid and the total phenolics decreased significantly, at a greater temperature and a longer roasting time. The greatest amount of pyrazines was produced from the IMM however, the amount of pyrazines decreased rapidly at $250^{\circ}C$ according to increasing in roasting time. The DPPH free radical scavenging activity was mostly 80% more effective than that of BHT and ${\alpha}$-tocopherol activities at the same concentration. In the case of the FRAP assay, the reducing power of the coffee slightly decreased at a greater temperature pand longer time. While the inhibitory effect on ${\alpha}$-glucosidase was negligible, the activity decreased by more than 80% when the coffee beans were roasted at $250^{\circ}C$ for 20 min. The inhibitory effect on ${\alpha}$-amylase showed similar results. Taken together, the optimum roasting conditions were determined to be $200^{\circ}C$ and 15 min, which provided the best physiological activity and nutty and chocolatey aromas from the pyrazine of coffee.