• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.987-996
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• 2009

Aspergillus niger GH1 previously isolated and identified by our group as a wild tannase producer was grown under solid-state (SSC) and submerged culture (SmC) conditions to select the enzyme production system. For tannase purification, extracellular tannase was produced under SSC using polyurethane foam as the inert support. Tannase was purified to apparent homogeneity by ultrafiltration, anion-exchange chromatography, and gel filtration that led to a purified enzyme with a specific activity of 238.14 IU/mg protein with a final yield of 0.3% and a purification fold of 46. Three bands were found on the SDS-PAG with molecular masses of 50, 75, and 100 kDa. PI of 3.5 and 7.1% N-glycosylation were noted. Temperature and pH optima were 600e and 6.0 [methyl 3,4,5-trihydroxybenzoate (MTB) as substrate], respectively. Tannase was found with a $K_M$ value of $0.41{\times}10^{-4}M$ and the value of $V_{max}$ was $11.03{\mu}$moL/min at $60^{\circ}C$ for MTB. Effects of several metal salts, solvents, surfactants, and typical enzyme inhibitors on tannase activity were evaluated to establish the novelty of the enzyme. Finally, the tannase from A. niger GH1 was significantly inhibited by PMSF (phenylmethylsulfonyl fluoride), and therefore, it is possible to consider the presence of a serine or cysteine residue in the catalytic site.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.407-418
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• 2015

This study is focused on establishing the optimal conditions to enhance the production of antilisterial substances by Lactobacillus paracasei BK57 isolated from Baikkimchi. In addition, the growth and in situ lactic acid and bacteriocin production of this strain were investigated during the manufacture of fresh cheese. And then the efficacy of using Lactobacillus starter as a protective culture to improve the safety of fresh cheese against Listeria monocytogenes KCTC 3569 was estimated. Maximum growth rate and activity of antibacterial substances were obtained in Lactobacilli MRS broth at $37^{\circ}C$ with controlled pH 6.0 after 30 h of incubation under aerobic condition. However, the growth rate and antimicrobial activity of bacteriocin produced in whole milk supplemented with yeast extract (2.0%) as a substrate were lower than those obtained in MRS broth. Live cells and cell-free culture supernatant of BK57 strain were effective in the suppression of L. monocytogenes in milk, whereas the inhibitory of the bacteriocin obtained from BK57 strain was higher in BHI broth than in milk. During storage at $4^{\circ}C$ and $15^{\circ}C$ for 6 days, no significant difference was found in the cell viability and antimicrobial activity of BK 57 strain in fresh cheese. In samples held at two temperatures, there was at least a 15% reduction in the numbers of the pathogen in fresh cheese artificially contaminated with approximately $10^5CFU/ml$ of L. monocytogenes within 6 days. Our results demonstrated the usefulness of L. paracasei BK57 having antilisterial activity as a biopreservative in the cheese making process.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.200-207
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• 2017

A new approach to the solubilization of waste activated sludge (WAS) using alginate-quaternary ammonium complex beads was investigated under controlled mild alkaline conditions. The complex beads were prepared by the reaction of sodium alginate (SA) with 3-(trimethoxysilyl)propyl-octadecyldimethylammonium chloride (TSA) in acid solution, followed by crosslinking with $CaCl_2$. Treatment of WAS with SA-TSA complex beads was effective for enhancing the efficacy of WAS solubilization. The highest value of soluble chemical oxygen demand (SCOD) concentration (3,900 mg/L) was achieved after 10 days of treatment with 30% (v/v) SA-TSA complex beads. The WAS solubilization efficacy of the complex beads was also evaluated by estimating the concentrations of volatile fatty acids (VFAs). The maximum value of VFAs was 2,961 mg/L, and the overall proportions of VFAs were more than 75% of SCOD. The main components of VFAs were acetic, propionic, iso-butyric, and butyric acids. These results suggest that SA-TSA complex beads might be useful for enhancing the solubilization of WAS. The potential use of VFAs as the external carbon substrate for the production of polyhydroxyalkanoate (PHA) by a mixed microbial culture (MMC) was also examined. The enrichment of PHA-accumulating MMC could be achieved by periodic feeding of VFAs generated from WAS in a sequencing batch reactor. The composition of PHA synthesized from VFAs mainly consisted of 3-hydroxybutyrate. The maximum PHA content accounted for 25.9% of dry cell weight. PHA production by this process is considered to be promising since it has a doubly beneficial effect on the environment by reducing the amount of WAS and concomitantly producing an eco-friendly biopolymer.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.2
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• pp.263-271
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• 2010

This trial was conducted to determine the effects of feeding a diet containing solid-state fermented rapeseed meal on performance, nutrient digestibility, intestinal ecology and intestinal morphology of broiler chickens. A mixed liquid culture, containing approximately 5 log cfu/ml Lactobacillus fermentum, Enterococcus faecium, Saccharomyces cerevisae and Bacillus subtilis was prepared in a 1:1:1:1 ratio. A basal substrate (BS) containing 75% rapeseed, 24% wheat bran and 1% brown sugar was mixed with the liquid culture in a ratio of 10:3. Over the 30-day fermentation, isothiocyanates were reduced from 119.6 to 14.7 mmol/kg. A total of 168, day-old male Arbor Acres broiler chicks were assigned to one of three dietary treatments including a corn-soybean meal based control diet as well as two experimental diets in which the control diet was supplemented with 10% of the BS containing unfermented rapeseed meal or 10% of the BS containing rapeseed meal subjected to solid state fermentation. There were 8 pens per treatment and 7 birds per pen. From days 19-21 and days 40-42, uncontaminated excreta were collected from each pen for digestibility determinations. In addition, digesta from the colon and ceca were collected to determine the number of lactobacilli, enterobacteria and total aerobes. The middle sections of the duodenum, jejunum, and ileum were collected for intestinal morphology. Over the entire experimental period (d 1-42), the weight gain and feed conversion of birds fed fermented rapeseed meal were superior (p<0.05) to that of birds fed nonfermented rapeseed meal and did not differ from the soybean control. On day 42, birds fed fermented rapeseed meal had higher (p<0.05) total tract apparent digestibility coefficients for dry matter, energy, and calcium than birds fed non-fermented rapeseed meal. Colon and ceca digesta from broilers fed the fermented feed had higher (p<0.05) lactobacilli counts than birds fed the control and non-fermented rapeseed meal diets on day 21 and 42. Fermentation also improved (p<0.05) villus height and the villus height:crypt depth ratio in the ileum and jejunum on day 21 and 42. The results indicate that solid-state fermentation of rapeseed meal enhanced performance and improved the intestinal morphology of broilers and may allow greater quantities of rapeseed meal to be fed to broilers potentially reducing the cost of broiler production.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.298-304
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• 2012

Among 63 Bacillus strains grown at $60^{\circ}C$ from sixteen samples of homemade Korean soybean paste, one strain was selected for producing the thermostable protease. The isolate has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. Culture filtrate of the isolate showed maximal protease activity at the reaction condition of $60-65^{\circ}C$ and pH 11. The culture filtrate retained more than 87% of initial protease activity after incubation for 30 min at $60^{\circ}C$ without substrate. In order to develop the medium composition, effects of ingredients including nitrogen sources, carbon sources, metal ions and phosphate were examined for protease production of the isolate. Lactose and soytone peptone were the most effective carbon and nitrogen source for the enzyme production. After the late logarithmic growth phase the isolate began to produce the protease, and the maximum protease productivity was reached to 550 unit/ml in the optimized medium consisting of lactose (3%), soytone peptone (1.5%), $MgSO_4$ (0.1%), $K_2HPO_4$ (0.03%), and $KH_2PO_4$ (0.03%) at 28 h of incubation.

• Journal of Mushroom
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• v.18 no.1
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• pp.91-94
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• 2020

This study was carried out to develop a method for cultivation of Lentinula edodes that would reduce both labor and waste. Cultural characteristics were studied, and mushroom yields were estimated to identify the most suitable method to culture L. edodes, using bottles and boxes. Among these, box cultivation with 7 kg of substrate had 40 days of browning period and the maximum yield of 945 g fruiting body; its biological efficiency was 32.7%. In contrast, box cultivation after pre-culture, and the bottle cultivation were found to be unsuitable for the production of L. edodes, due to long periods of browning, and low yields with poor quality, respectively. Further studies on box cultivation of L. edodes are necessary for commercial application of this method.

• Development and Reproduction
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• v.5 no.1
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• pp.17-21
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• 2001

This study was conducted to investigate the expression pattern of Trypsin-like enzyme and the effect of a trypsin inhibitor(benzimidine) on hatching process during in-vitro culture of mouse preimplantation embryos. The Trypsin-like enzyme was identified by rhodamine-conjugated Trypsin substrate probe. The expression of trypsin-like enzyme was firstly detected at the late morula stage, and the enzyme was uniformly localized in the trophectoderm of late blastocysts. Especially, intense fluorescence was observed in the blebbing area of hatching blastocysts. Bisbenzamidine, contained in culture media, did not alter embryonic development from 4-cell stage to the expanded blastocyst but decrease the hatching rate in ImM concentration (15.8% vs 89.7%, p<0.02). In the treatment of bisbenzimidine (5mM) for 12 hours according to the embryonic stage of mouse, the hatching rate of control (83.0%) and treatment in late blastocysts (8.7%) were significantly (p<0.01) different. From these results, we suggested that the hatching enzyme having trypsin-like activity was localized from the late morula stage, and the hatching process by this enzyme was activated in the late blastocyst stage of mouse embryos.

• Journal of the Korean Society of Food Culture
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• v.20 no.6
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• pp.703-708
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• 2005

This study was carried out to compare the antioxidant activities of the ether, butanol, water extracts from chestnut inner shell(Castanea crenata Sieb. et Zucc.) with those of tocopherol and BHA in soybean oil. All additives were added to soybean oil on the quantities of 0.02%. Comparing the antioxidant activities under autooxidation condition at $45.0{\pm}0.5$ for 42days of the extracts were recorded in the order of butanol>ether>control>BHA>tocopherol depending on the solvent. Under the condition at $60.0{\pm}0.5^{\circ}C$ for 32days, the butanol extracts represented the high antioxidation effect, however, there was no significant differences between the ether extracts and control. Under thermal oxidation condition, the ether extract showed stronger antioxidant activity than those of the butanol extract. In the results of polyphenol compound analysis, ellagic acid, quercetin, morin, naringenin, flavanol were included in the ether extracts and ellagic acid, naringenin, gallic acid, flavanol were included in the butanol extracts, respectively. Among them, ellagic acid in ether extract and gallic acid and naringenin in butanol extracts seed to increase the antioxidant activities in the substrate oil.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.840-845
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• 2011

Degradation products of agarose are biologically active and thus used as an ingredient in pharmaceuticals or functional cosmetics. Furthermore, it has been strongly considered as a substrate for bio-ethanol fermentation. Recently, we isolated new agarase-producing microorganism, Pseudoalteromonas sp. from south sea of Korea. In this study, we aimed to separate and purify the agarase from culture broth of this strain. Separation of agarase was performed by ion- exchange chromatography on DEAE-Sepharose resin. Equilibrium pH and volume ratio of resin to the amount of protein were optimized for the efficient adsorption of protein. 410 ${\mu}g$ of protein was completely adsorbed to 3 mL of resin at pH 7.5. The total amount of eluted protein increased as NaCl concentration increased to 400 mM at isocratic elution. Agarase was separated by linear gradient elution of NaCl (0~1,000 mM). Three major protein peaks were observed and the presence or absence of agarase in these eluted proteins was measured by Lugol's staining technique. Only six eluted protein fractions showed strong agarase activity.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.165-171
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• 2006

ERM proteins transfer the methyl group to $A_{2058}$ in 23S rRNA to confer the resistance to MLS (macrolide-lincosamide-streptogramin B) antibiotics on microorganism ranging from antibiotic producers to pathogens. To define the functional role of peptide segment encompassing amino acid residues 1 to 25 in NTER (N-terminal end region) of ErmSF, one of the ERM proteins, DNA fragment encoding mutant protein deprived of that peptide was cloned and overexpressed in E. coli to obtain a purified soluble form protein to the apparent homogeneity in the yield of 12.65 mg per liter of culture. The in vitro activity of mutant protein was found to be 85% compared to wild type ErmSF, suggesting that this peptide interact with substrate to affect the enzyme activity. This diminished activity of mutant protein caused the delayed expression of antibiotic resistance in vivo, that at fIrst cells expressing mutant protein showed the retarded growth due to the antibiotic action but with time cells inhibited by antibiotic gradually recovered the viability to exert the resistance to the same extent as those with wild type protein.