• Microbiology and Biotechnology Letters
• /
• v.20 no.6
• /
• pp.625-629
• /
• 1992

This work was carried out to study physiological characteristics of Rhodosporidium toru[oides cells having two different mating types. The mating type A produces internal. cell wall-bound, and external invertases while type a produces only two invertases except external invertase. Comparing their characteristics after partial purification of internal invertases from both mating type cells, invertase from type a has decreased 15% of invertase activity only by $Mn^{2+}$ I while invertase from type A has been increased 11% of invertase activity by $Zn^{2+}$ and decreased 15% of invertase activity by $Mn^{2+}$ On the effect of enzyme inhibitor, invertase of type a was inhibited from 12% to 57% by 2-mercaptoethanol, sodium dodecyl sulfate, phenol. but invertase of type A was slightly inhibited only by phenol. The thermal stability of both invertases has showed steep inactivation at above $80^{\circ}C$ and their optimal temperatures were similar at $60^{\circ}C$ . Invertase from type A showed stability only on condition of acid from pH 3 to 6 and its opimal pH was 5.0, while invertase from type a showed stability at the wide range of pH 3-10 and its optimal pH was 4.0. And the $K_m$ values of invertases from type A and type a were $2.5{\times}10^3$M and$3.4{\times}10^3$M, respectively.

• Journal of Aquaculture
• /
• v.20 no.3
• /
• pp.184-189
• /
• 2007

Treatment conditions for the induced diploid gynogenesis, a maternal-exclusive form of artificial parthenogenetic reproduction, were optimized in bagrid catfish (Leiocassis ussuriensis, Siluriformes). Optimal amounts of ultraviolet (UV) irradiation for the genetic inactivation of spermatozoa in bagrid catfish and Pseudobagrus fulvidraco were proven to be ranged from 3,600 to 4,800 $ergs/mm^2$ based on the examination of viability of embryos and haploid incidence. Haploid embryos were restored to diploidy by preventing the extrusion of the second polar body using cold shock treatment. Thermal treatments (4 or $6^{\circ}C$ for 30, 40 or 50 min) were carried out 3, 5 or 7 min post insemination. Best scores for embryo viability (38.6% of total eggs taken) and incidence of normal diploidy (87.9% of hatched larvae) were observed at the embryo group treated at $4^{\circ}C$ for 40 min, 5 min after insemination. Restoration of gynogenetic diploidy was confirmed based on the absence of haploid syndrome, cell size and/or nucleolar organizing region (NOR) counts.

• Research in Plant Disease
• /
• v.7 no.1
• /
• pp.1-7
• /
• 2001

An isolate of Cucumber mosaic cucumovirus(CMV) was isolated from Hydrangea macrophylla for. otaksa(Sieb. et Zucc. ) Wils. showing mosaic symptoms, and designated as Hm-CMV. Hm-CMV was characterized by the tests of host range, physical properties, serological properties, RNA and coat protein compositions, and reverse transcription and polymerase chain reaction (RT-PCR) analysis. Twelve species in 4 families were used in the host range test of Hm-CMV and could be differentiated from Y-CMV used as a control CMV by the ringspot and line pattern on inoculated leaves of several tobacco plants. Thevirus produced local lesions on inoculated leaves of Chenopodium amarticolor, C. quinoa and Vigna unguiculata. The physical properties of the virus were as follows; thermal inactivation point(TIP) was 60$\^{C}$, dilution end point (DEP) was 10$\^$-3/, and longevity in vitro (LIP) was 3∼4 days. Hm-CMV was serologically identical to Y-CMV. SDS-polyaciylamide gel electrophoresis(SDS-PAGE) showed one major protein band of about 28 kDa. In RNA or dsRNA analysis, Hm-CMV consisted of four RNA or dsRNA species, but satellite RNA was not detected. In RT-PCR using CMV-common primer and CMV subgroup I-specific primer, bothe amplified expected size of about 490 bp and 200 bp DNA fragments from Hm-CMV, respectively. Restriction enzyme analysis of the 490 bp RT-PCR products using EcoR I and Msp I showed that Hm-CMV belonged to CMV subgroup I. However, Hm-CMV could be differentiated from other CMV subgroup I isolates by RNA fingerprinting by arbitrarily primed polymerase chain reaction (RAP-PCR).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.2
• /
• pp.125-136
• /
• 1990

To develope a rapid processing method for fish sauce, processing conditions of fish sauce from sardine waste was investigated. The chopped waste was homogenized and hydrolyzed by commercial proteolytic enzymes such as Complex enzyme-2000($2.18\cdot10^4$ U/g solid) and Alcalase($1.94\cdot10^4$ U/g solid) in a cylindrical vessel with 4 baffles and 6-bladed turbine impeller. Optimal temperature for the case of hydrolysis with Complex enzyme-2000 was 50 and that with Alcalase was $55^{\circ}C$. In both cases, the reasonable pH, amount of water for homo-genization, enzyme concentration and hydrolyzing time were 8.0, $40\%$ (W/W), $3\%$ and 100 min, respectively. Heating of the filtrated hydrolysate for 2 hours at $90^{\circ}C$ with $6\%$ of invert sugar was suitable for pasteurization of the hydrolysate and inactivation of enzymes. Flavor, taste and color of the hydrolysate was improved during the thermal treatment in which the browning reaction products might participate and result in antioxidative and bactericidal effects. Combined use of $0.005\%$ of Caryophylli flos with invert sugar was also effective for the improvement of taste. Yield of the fish sauce based on the total nitrogen in the raw sardine waste was $91.2\~92.3\%$ and $87.2\~87.8\%$ of the total nitrogen in the fish sauce was in the form of amino nitrogen. The pH, salinity and histamine content of the fish sauce prepared with $15\%$ of table salt were $6.1\~6.2$, $14.2\~14.4\%$ and less than $10mg\%$, respectively. The fish sauce was stable during the storage of 60 days at $26\pm3^{\circ}C$ on bacterial growth and its quality was also maintained.

• Applied Biological Chemistry
• /
• v.24 no.3
• /
• pp.186-193
• /
• 1981

Three fractions of carboxymethyl-cellulase (F-I, F-II, and F-III) and ${\beta}-glucosidase$ form Aspergillus niger were partially purified by ammonium sulfate fractionation. Sephadex G-150 and DEAE-Sephadex column chromatography. The optimum conditions such as pH and temperature and thermal inactivation properties of the enzymes were investigated. Arrhenius plots of F-II and F-III appeared as straight lines, whereas that of F-I was biphasic. The Z-values of F-II and F-III were $8^{\circ}C$ and $10^{\circ}C$ respectively, while that of F-I was $4^{\circ}C$ over $60{\sim}70^{\circ}C$ and $383^{\circ}C$ over $70{\sim}98^{\circ}C$. Three fractions and the crude extract of carboxymethyl-cellulase exhibited a similar optimum pH 4.3 and temperature of $60^{\circ}C$, while Z-value of crude extract $(21.5^{\circ}C)$ was much higher than that of the purified enzyme. Maximum activity of both purified and crude extract of ${\beta}-glucosidase$ was shown at pH 4.7 and $60^{\circ}C$, and z-value of the enzyme was $7^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.5
• /
• pp.361-372
• /
• 1990

Processing conditions of whole sardine into modified fish sauce were investigated. Thawed and chopped sardine was homogenized and hydrolyzed using commercial proteolytic enzymes such as complex enzyme-2000($2.18{\cdot}10^4U/g solid$) and alcalase($1.94{\cdot}10^4\;U/g solid$) in a cylindrical vessel with 4 baffles and 6-bladed impeller. Optimal pH, enzyme concentration and temperature for the hydrolysis with complex enzyme-2000 were 7.0, $7\%$ (W/W) and $52^{\circ}C$, and-those with alcalase were 8.0, $6\%$ (W/W) and $60^{\circ}C$. In both cases, the reasonable amount of water for homogenization, agitation speed and hydrolyzing time were $100\%$ (W/W), 100 rpm and 210 minutes. Thermal treatment of the filtered hydrolysate at $90^{\circ}C$ for 2 hours with $6\%$ of invert sugar was adequated to inactivation of the enzymes and pasteurization of the hydrolysate. Flavor, taste and color of the hydrolysate were improved during the heating process in which the browning products might participate. The content of free amino nitrogen in the fish sauce seasoned with $15\%$ of table salt was ca. $1,640 mg\%$. Yield of the fish sauce based on the contents of proteinous and free amino nitrogen in the raw whole sardine was ca. $86\%$, and ca. $96\%$ of these compounds of the fish sauce was in the form of free amino nitrogen. The pH, salinity and histamine content of the fish sauce were $6.1\~6.3,\;14.2\~14.3\%$ and less than $10\;mg\%$.

• Korean journal of applied entomology
• /
• v.23 no.1 s.58
• /
• pp.15-21
• /
• 1984

The virus infecting French bean (Phaseolus vulgaris L.) was identified as Bean Common Mosaic Virus(BCMV) based on the host range, symptomatology, serology, morphology of virus particles and inclusion bodies. Isolates of BCMV were obtained from seeds of P. vulgaris collected at Suweon, Jangsu and Jinju in Korea. French bean produced vein clearing, mosaic, stunting and leaf curling. Symptom of Chenopodium quinoa was local lesions on the inoculated leaves, not on the upper leaves. The electron micrograph of the virus from French bean was flexuous approximately 750nm in length. Cylindrical and pinwheel cytoplasmic inclusion bodies were observed in French bean leaf infected by BCMV. BCMV from the French bean was transmitted through seed and green peach aphid, Myzus persicae. The thermal inactivation point was $55\~60^{\circ}C$, dilution end point was $10^{-3}\~10^{-5}$ and longevity in vitro was $2\~3$ days for BCMV from French bean. The isolates of BCMV reacted positively against BCMV antiserum. The extract of BCMV infected bean leaves, Azukibean mosaic virus (AZMV) and Cowpea aphid borne mosaic virus(CaMV) also reacted with BCMV antiserum, however, BCMV and CaMV showed the spur in agar gel diffusion test.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.6
• /
• pp.1095-1101
• /
• 2001

Spinach was minimally processed into the unseasoned side dish to be used for Korean food service industry, using the techniques of cook-chill and sous vide. Spinach was blanched at 10$0^{\circ}C$ for 6 minutes, vacuum-packaged in the unit of 500 g by plastic film of low gas permeability, pasteurized at 9$0^{\circ}C$ and then cooled rapidly at 3$^{\circ}C$. The chilled products were then stored at 3 and 1$0^{\circ}C$ with measurement in their quality. Six log cycle (6D) inactivation of Listeria monocytogenes and 13 log (13D) thermal destruction of Streptococcus faecalis were compared as two pasteurization conditions, which corresponded to heating for 22.8 and 30.0 minutes at 9$0^{\circ}C$, respectively. Milder heat processing based on 6D process of L monocytogenes gave better quality of color, texture, ascorbic acid and chlorophyll than the conditions of 13D process of S. faecalis. Any microbial growth in total aerobic, psychrophilic and anaerobic bacteria was not observed until 8 days at 1$0^{\circ}C$ and 14 days at 3$^{\circ}C$, which might be regarded as strict guidelines of shelf life. Storage times based on the changes in physical and chemical quality were longer than those based on strict microbial quality in case of the products pasteurized by 6D process of L. monocytogenes. The seasoned vegetables prepared from sous vide processed spinach were found to be inferior in sensory quality to those from freshly blanched one.

• Applied Biological Chemistry
• /
• v.39 no.5
• /
• pp.333-337
• /
• 1996

For continuous production of galactooligosaccharides(GOS), $\beta-galactosidase$ with h1gh transgalactosylation activity from Bacillus sp. A 4442 was Immobilized onto $Diaion^{TM}$ HPA 75(styrene-divinylbenzene resin). The parameters influencing enzyme immobilization were scrutinized in order to maximize immobilization yield while minimizing enzyme inactivation. The optimum conditions turned out to be: Tris buffer concentration 30 mM, pH 8.0, contact time at room temperature 3 hr, and enzyme loading 25 mg protein/g resin. Both the thermal stability and the operational stability of immobilized enzyme were markedly enchanced by the treatment with 0.5% glutaraldehyde as a cross-linker. Under the experimental conditions established, the yield of ${\beta}-galactosidase$ immobilization was 40% or more and the activity of the immobilized enzyme ca. 200 U/g resin. When a packed-bed reactor was employed to continuously convert lactose to GOS, the specific production, which refers to as the amount of commercially valuable GOS produced by a unit amount of immobilized ${\beta}-galactosidase$, was found to be ca. 300 g GOS/g carrier.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.5
• /
• pp.447-454
• /
• 1991

Chopped garlic was added to beef to determine its effect on the protein digestion during storage and heat treatment. The digestibility of raw beef without garlic was not significantly changed during storage at $4^{\circ}C$, but increased as garlic added and aging time increased. The optimal aging time and amount of garlic added was varied with heating time. Trypsin inhibitor did not change the digestibility of beef due to its thermal inactivation. Gel chromatography revealed that the lower molecular weight peptides(2,200~6,150 dalton) were shown in beef-garlic mixture through aging and heating procedure. When aged beef with garlic was digested with four-enzyme system, the soluble portion was increased significantly in comparison with that from raw beef without garlic. Protein quality of beef, as measured by computed PER(C-PER), was improved from 2.14 of raw beef to 2.50 of aged beef with chopped garlic.