Sang-Mee Lee

Screening of Biological Activity of Solvent Extract from Styela clava Tunic for Fishery Waste Recycling

Styela clava tunic is generated in large amounts as a waste from S. clava processing plants and causes environmental problem. Although biological activities of S. clava were reported by many investigators, study on S. clava tunic was little. In this study, therefore, tyrosinase inhibition and antioxidative activities of extracts from S. clava tunic using different solvent were investigated for recycling of the fishery waste. Among extraction methods tested, autoclaved extraction (25.7%) and hot water extraction (18.2%) appeared to be effective for extraction. The highest total phenolic content was 46.6 mg/g in autoclaved extract while the highest flavonoid content was 23.0 mg/g in chloroform extract. All extracts possessed tyrosinase inhibition activity and the inhibition activity was concentration-dependent. Inhibition concentration () against tyrosinase activity was mg/ml in ethanol extract, mg/ml in acetone extract and 0.27 mg/ml in n-butanol extract. Among extracts tested, hot water and autoclaved extracts displayed higher antioxidative activity than organic solvent extracts. Therefore, our data suggest that extract from S. clava tunic may potential candidate for cosmetic product with whitening effect and medicine for diseases caused by various oxidative stresses.

Static Culture Condition for Production of Bacterial Cellulose, Environment-Friendly Functional Material, by Acetic Acid Bacteria

Abstract Bacterial cellulose (BC) has played important role as new functional material for food industry and industrial products based on its unique properties. The interest in BC from static cultures has increased steadily in recent years because of its potential for use in medicine and cosmetics. In this study, we investigated culture condition for BC production by Acetobacter sp. F15 in static culture. The strain F15, which was isolated from decayed fruit, was selected on the basis of BC thickness. The optimal medium compositions for BC production were glucose 7%, soytone 12%, K 2 HPO 4 0.2%, NaH 2 PO 4 ㆍ 2H 2 O 0.2%, lactic acid 0.05% and ethanol 0.3%, respectively. The strain F15 was able to produce BC at 26 ℃ -36 ℃ with a maximum at 32 ℃ . BC production occurred at pH 4.5-8 with a maximum at pH 6.5. Under these conditions, a maximum BC thickness of 12.15 mm was achieved after 9 days of cultivation; this value was about 2.3-fold higher than the thickness in basic medium. Scanning electron micrographs showed that BC from the optimal medium was more compact than plant cellulose and was reticulated structure consisting of ultrafine cellulose fibrils. BC from the optimal medium was found to be of cellulose type I, the same as typical native cellulose.

Characteristics of White Soybean Chungkookjang Fermented by Bacillus subtilis D7

This study was carried out to investigate the characteristics of white soybean Chungkookjang fermented by Bacillus subtilis D7. The highest germination rate was obtained under 25°C when water was supplied for 4 days at intervals of 2 hr. The total isoflavone content was 971.3 μg/g before germination and 1023.8 μg/g after germination. The amino typeand ammonia type-nitrogen contents of Chungkookjang were proportional to the fermentation time. The pH values of all Chungkookjang soybeans increased up to pH 7.8-8.0 during fermentation. The number of viable cells in all Chungkookjang soybeans increased significantly up to 24 hr. The protease activity of all Chungkookjang soybeans increased up to 30-36 hr. The αand β-amylase activities of Chungkookjang fermented by B. subtilis D7 were enhanced with increasing fermentation time. Analysis of the effect of Chungkookjang intake on the liver function of mouse showed that the alkaline phosphatase (ALP) activity and the superoxide dismutase (SOD) activity in the Chungkookjang diet group were markedly higher than those in the control group. The asparatate aminotransferase (AST) activity in the germinated soybean Chungkookjang diet group was higher than that in the nongerminated soybean Chungkookjang diet group. Therefore, Chungkookjang soybeans fermented with B. subtilis D7 can be expected to have an increased content of functional components and improved quality characteristics.This study was carried out to investigate the characteristics of white soybean Chungkookjang fermented by Bacillus subtilis D7. The highest germination rate was obtained under 25°C when water was supplied for 4 days at intervals of 2 hr. The total isoflavone content was 971.3 μg/g before germination and 1023.8 μg/g after germination. The amino type- and ammonia type-nitrogen contents of Chungkookjang were proportional to the fermentation time. The pH values of all Chungkookjang soybeans increased up to pH 7.8-8.0 during fermentation. The number of viable cells in all Chungkookjang soybeans increased significantly up to 24 hr. The protease activity of all Chungkookjang soybeans increased up to 30-36 hr. The α- and β-amylase activities of Chungkookjang fermented by B. subtilis D7 were enhanced with increasing fermentation time. Analysis of the effect of Chungkookjang intake on the liver function of mouse showed that the alkaline phosphatase (ALP) activity and the superoxide dismutase (SOD) activity in the Chungkookjang diet group were markedly higher than those in the control group. The asparatate aminotransferase (AST) activity in the germinated soybean Chungkookjang diet group was higher than that in the nongerminated soybean Chungkookjang diet group. Therefore, Chungkookjang soybeans fermented with B. subtilis D7 can be expected to have an increased content of functional components and improved quality characteristics.

Fermentation Characteristics of Chungkookjang Prepared Using Different Soybean

Abstract This study was carried out to investigate changes of protease and amylase activities and nitrogen content in Chungkookjang prepared by Bacillus subtilis S8 and different soybean. Amino-type nitrogen and ammonia-type nitrogen contents increased with an increase in fermentation time and was the highest in black soybean Chungkookjang. The number of viable cells increased up to 24 h of fermentation at all temperatures tested; especially, their levels were the highest at 40. Protease activity was the highest in black soybean Chungkookjang. α-amylase activity increased significantly up to 6 h of fermentation at 30and 40and then maintained constantly. It also increased up to 30-36 h of fermentation at 45and then decreased. β-amylase activity was the highest in black soybean Chungkookjang at 35and 40and in yellow soybean Chungkookjang at 45. Production pattern of reducing sugar was similar to that of β-amylase. Amino-type nitrogen, viable cell number and reducing sugar content and β-amylase activity was the highest in Chungkookjang fermented at 40. Considering amino-type and ammonia-type nitrogen contents, Chungkookjang fermentation using yellow soybean was favorable. However, the fermentation using black soybean was favorable, considering protease and amylase activities and reducing sugar content.Key words: Bacillus subtilis, Chungkookjang, Fermentation, Soybean cultivar

Characteristics of Bacteria-Originated Keratinase for Feather Waste Treatment

Keratin wastes are generated in excess of million tons per year worldwide and biodegradation of keratin by microorganisms possessing keratinase activity can be used as an alternative tool to prevent environmental pollution. For practical use of keratinase, its physicochemical properties should be investigated in detail. In this study, we investigated characteristics of keratinase produced by Xanthomonas sp. P5 which is isolated from rhizospheric soil of soybean. The level of keratinase produced by the strain P5 increased with time and reached its maximum (10.6 U/ml) at 3 days. The production of soluble protein had the same tendency as the production of keratinase. Optimal temperature and pH of keratinase were 40℃-45℃ and pH 9, respectively. The enzyme showed broad temperature and pH stabilities. Thermostability profile showed that the enzyme retained 94.6%-100% of the original activity after 1 h treatment at 10℃-40℃. After treatment for 1 h at pH 6-10, 89.2%-100% of the activity was remained. At pH 11, 71.6% of the original activity was retained after 1 h treatment. Although the strain P5 did not degrade human hair, it degraded duck feather and chicken feather. These results indicate that keratinase from Xanthomonas sp. P5 could be not only used to upgrade the nutritional value of feather hydrolysate but also useful in situ biodegradation of feather.

Isolation and Characterization of Bacillus Strain as a Potential Biocontrol Agent

In this study, to retain a stable bacterial inoculant, Bacillus strains showing antifungal activity were screened. The improved production, antifungal mechanism, and stability of the antifungal metabolite by a selected strain, AF4, a potent antagonist against phytopathogenic Botrytis cinerea, were also investigated. The AF4 strain was isolated from rhizospheric soil of hot pepper and identified as Bacillus subtilis by phenotypic characters and 16S rRNA gene analysis. Strain AF4 did not produce antifungal activity in the absence of a nitrogen source and produced antifungal activity at a broad range of temperatures (25-40°C) and pH (7-10). Optimal carbon and nitrogen sources for the production of antifungal activity were glycerol and casein, respectively. Under improved conditions, the maximum-antifungal activity was 140±3 AU/ml, which was higher than in the basal medium. Photomicrographs of strain AF4-treated B. cinerea showed morphological abnormalities of fungal mycelia, demonstrating the role of the antifungal metabolite. The B. subtilis AF4 culture exhibited broad antifungal activity against several phytopathogenic fungi. The antifungal activity was heat-, pH-, solvent-, and protease- stable, indicating its nonproteinous nature. These results suggest that B. subtilis AF4 is a potential candidate for the control of phytopathogenic fungi-derived plant diseases.

Isolation and Characteristics of a Phenol-degrading Bacterium, Rhodococcus pyridinovorans P21

The effluents of chemical and petroleum industries often contain non-biodegradable aromatic compounds, with phenol being one of the major organic pollutants present among a wide variety of highly toxic organic chemicals. Phenol is toxic upon ingestion, contact, or inhalation, and it is lethal to fish even at concentrations as low as 0.005 ppm. Phenol biodegradation has been studied in detail using bacterial strains. However, these microorganisms suffer from substrate inhibition at high concentrations of phenol, whereby growth is inhibited. A phenol-degrading bacterium, P21, was isolated from oil-contaminated soil. The phenotypic characteristics and a phylogenetic analysis indicated the close relationship of strain P21 to Rhodococcus pyridinovorans. Phenol biodegradation by strain P21 was studied under shaking condition. The optimal conditions for phenol biodegradation by strain P21 were 0.09% , 0.1% , 0.3% , 0.015% , 0.001% , initial pH 9, and , respectively. When 1,000 ppm of phenol was added to the optimal medium, the strain P21 completely degraded it within two days. Rhodococcus pyridinovorans P21 could grow in up to 1,500 ppm of phenol as the sole carbon source in a batch culture, but it could not grow in a medium containing above 2,000 ppm. Moreover, strain P21 could utilize toxic compounds, such as toluene, xylene, and hexane, as a sole carbon source. However, no growth was detected on chloroform.

Antioxidant Production by Bacillus methylotrophicus Isolated from Chungkookjang, Korean Traditional Fermented Food

Although antioxidant activities of Korean traditional fermented foods were reported by many researchers, study on antioxidant activity of microorganism originated from Korean traditional fermented foods was little. Therefore, we improved condition for antioxidant production by a bacterium isolated from home-made Chungkookjang. We selected a bacterial strain, which showed the highest antioxidative activity, from Chungkookjang and then named GJ. The selected GJ strain was identified as Bacillus methylotrophicus by alignment data of 16S rRNA gene nucleotide sequences. Improved medium compositions for DPPH radical scavenging activity were 0.25% sucrose, 1% peptone, 0.01% MgSO4·7H2O and initial pH 6.5, respectively. Optimal culture conditions were 30 , 200 rpm and 4% inoculum volume, respectively. In improved conditions, DPPH radical scavenging activity of GJ reached to 91% in a short time. The strain GJ also possessed ACE inhibition and other antioxidative activities; ACE inhibition activity (49.4%), ABTS radical scavenging activity (99.8%), metal chelating activity (67.9%), SOD-like activity (36.5%) and reducing power (A700 = 5.982) were observed, respectively. Therefore, our results suggest that B. methylotrophicus GJ strain may be potential candidate for functional foods, cosmetic products for anti-aging and medicine for diseases caused by oxidative stress.

Keratinase Production by Recalcitrant Feather Degrading Pseudomonas Geniculata and Its Plant Growth Promoting Activity

Abstract We investigated the optimal conditions for keratinase production by feather-degrading Pseudomonas geniculata H10 using one variable at a time (OVT) method. The optimal medium composition and cultural condition for keratinase production were determined to be glucose 0.15% (w/v), beef extract 0.08% (w/v), KH 2 PO 4 0.12% (w/v), K 2 HPO 4 0.02% (w/v), NaCl 0.07% (w/v), MgSO 4 ․ 7H 2 O 0.03%, MgCl 2 ․ 6H 2 O 0.04% along with initial pH 10 at 200 rpm and 25 ℃ , respectively. The production yield of keratinase was 31.6 U/ml in an optimal condition, showing 4.6-fold higher than that in basal medium. The strain H10 also showed plant growth promoting activities. This strain had ammonification activity and produced indoleacetic acid (IAA), siderophore and a variety of hydrolytic enzymes such as protease, lipase and chitinase. Therefore, this study showed that P. geniculata H10 could be not only used to upgrade the nutritional value of feather wastes but also useful in situ biodegradation of feather wastes. Moreover, it is also a potential candidate for the development of biofertilizing agent applicable to crop plant soil.