• Korean journal of applied entomology
• /
• v.42 no.3
• /
• pp.203-209
• /
• 2003

Biological characteristics of the almond moth, Cadra cautella, of which eggs will be substitute diets for Orius spp. and Trichogramma spp., were investigated and a mass-rearing system for the moth was developed. At 25$^{\circ}C$, egg, larval, and pupal period was 4.2, 29.8 and 8.3 days, respectively, and adult longevity was 5.8 days for female and 4.8 days for male. Total number of eggs at 20, 25 and 30$^{\circ}C$ was 128.9,207.9 and 139.9, respectively. The moth could be successfully reared with all food substrates tested, of which rice bran (50%)+chick feed (50%) assumed to be proper for massrearing in view of cost. Eggs could be stocked at 9 C for 7 days, representing 82% hatchability. In the rearing cage (16${\times}$24${\times}$9cm) used, 1,000 eggs was better for initial level of inoculation, showing relatively high emergence rate and adult weight. Mass-rearing procedures were explained in detail.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.3
• /
• pp.359-366
• /
• 1993

Molds are eucaryotic, multicellular, multinucleate, filamentous organisms that reproduce by forming asexual and sexual spores. The spores are readily spread through the air and because they are very light-weight and tend to behave like dust particles, they are easily disseminated on air currents. Molds therefore are ubiquitous organisms that are found everywhere, throughout the environment. The natural habitat of most molds is the soil where they grow on and break down decaying vegetable matter. Thus, where there is decaying organic matter in an area, there are often high numbers of mold spores in the atmosphere of the environment. Molds are common contaminants of plant materials, including grains and seeds, and therefore readily contaminate human foods and animal feeds. Molds can tolerate relatively harsh environments and adapt to more severe stresses than most microorganisms. They require less available moisture for growth than bacteria and yeasts and can grow on substrates containing concentrations of sugar or salt that bacteria can not tolerate. Most molds are highly aerobic, requiring oxygen for growth. Molds grow over a wide temperature range, but few can grow at extremely high temperatures. Molds have simple nutritional requirements, requiring primarily a source of carbon and simple organic nitrogen. Because of this, molds can grow on many foods and feed materials and cause spoilage and deterioration. Some molds ran produce toxic substances known as mycotoxins, which are toxic to humans and animals. Mold growth in foods can be controlled by manipulating factors such as atmosphere, moisture content, water activity, relative humidity and temperature. The presence of other microorganisms tends to restrict mold growth, especially if conditions are favorable for growth of bacteria or yeasts. Certain chemicals in the substrate may also inhibit mold growth. These may be naturally occurring or added for the purpose of preservation. Only a relatively few of the approximately 100,000 different species of fungi are involved in the deterioration of food and agricultural commodities and production of mycotoxins. Deteriorative and toxic mold species are found primarily in the genera Aspergillus, Penicillium, Fusarium, Alternaria, Trichothecium, Trichoderma, Rhizopus, Mucor and Cladosporium. While many molds can be observed as surface growth on foods, they also often occur as internal contaminants of nuts, seeds and grains. Mold deterioration of foods and agricultural commodities is a serious problem world-wide. However, molds also pose hazards to human and animal health in the form of mycotoxins, as infectious agents and as respiratory irritants and allergens. Thus, molds are involved in a number of human and animal diseases with serious implication for health.

• Journal of Mushroom
• /
• v.10 no.3
• /
• pp.129-135
• /
• 2012

This study was carried out to investigated optimum mixing ratio of Korean natural Cudrania tricuspidata for production of functional oyster mushroom. Total nitrogen and carbon source of Cudrania tricuspidata was 0.27% and 40.9%, respectively and C/N ratio was 152. Total nitrogen source and pH of substrates mixed with Cudrania tricuspidata were 2.7~2.8 and 4.9~5.1, respectively. The contents of $P_2O_5$, CaO, MgO and $Na_2O$ were no significant difference. Mycerial growth was faster at Cudrania tricuspidata 10% than that of control, but the other treatment was slower. Yields of fruiting body was the highest at Cudrania tricuspidata 20%, and diameter and thick of pileus were no significant difference to increase of Cudrania tricuspidata addition ratio. The L value of pileus was the highest at the Cudrania tricuspidata 20% during mushroom harvest, but there was no significant difference in the a-value and the b-value. Chemical contents of fruiting body were the highest at the Cudrania tricuspidata 30%.

• Korean Journal of Environmental Agriculture
• /
• v.21 no.4
• /
• pp.269-273
• /
• 2002

A 0.19 hectare stream water purification demonstration wetland was constructed and planted with cattails from April 2001 to May 2001. Some portions of its bottom surfaces adjacent to levees have a variety of slope of 1:4 $\sim$ 1:15 and two small open water areas were installed in the wetland. These make its shape closer to a natural wetlant Nitrogen removal was a major objective of the wetlant Waters of Sinyang Stream flowing into Kohung Esturiane Lake located southern coastal region of Korean Peninsula were pumped and funneled into it. Volumes and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Average inflow and outflow were 120 $m^3/d$ and 112 $m^3/d$, respectively. Hydraulic retention time was about 3.1 days. Average nitrate and total nitrogen removal rate for the early stage of the wetlands were 85.8 $mg/m^2/day$, 171.4 $mg/m^2/day$ respectively. Full establishment of cattails within a few years can develope litter-soil substrates and supply available carbon sources beneficial to the denitrification of nitrate. These can lead to increases of the nitrate retention rate. Short circuiting and dead zone areas which might be occurred due to the close-to-nature layout of the wetland were not observed during the monitoring period.

• Microbiology and Biotechnology Letters
• /
• v.44 no.4
• /
• pp.540-549
• /
• 2016

Plant residues serve as substrates for the proliferation and overwintering of plant pathogenic fungi in soil. Effects of the biocontrol fungus Trichoderma harzianum on the colonization of wheat straw by the plant pathogenic fungus Fusarium solani were investigated under different soil moisture regimes (-50 vs. -500 kPa) in non-sterile soil. T. harzianum ThzID1-M3 and/or F. solani were added along with wheat straw to non-sterile soils. ThzID1-M3, other Trichoderma species, and F. solani were monitored for a 21-day period using quantitative PCR. ThzID1-M3 reduced the colonization of F. solani on wheat straw (p < 0.05) under both moisture regimes, and F. solani reduced the colonization by ThzID1-M3 and other Trichoderma species (p < 0.05), thus suggesting competitive inhibition between ThzID1-M3 and F. solani. Colonization by ThzID1-M3 and generic Trichoderma was improved in the wet soil (p < 0.05), but colonization by F. solani did not differ between the two moisture conditions. Thus, the inhibitory effect of ThzID1-M3 was greater in the wet soil (p < 0.05). The growth competition between ThzID1-M3 and F. solani to colonize plant debris suggests that the biocontrol fungus T. harzianum may reduce the potential of the plant pathogen, F. solani, to survive and proliferate on crops.

• Journal of Wetlands Research
• /
• v.9 no.1
• /
• pp.107-114
• /
• 2007

This study aimed to investigate the hexachlorobenzene (HCB) dechlorinating ability of sediment microbes collected from a natural canal receiving secondary effluents from an industrial estate and nearby factories. Nine sites along the stream and one in the estuary in the Gulf of Thailand into which the canal spills were specified and sampling for sediment and water. Preliminary analysis of the sediments showed that the first four sites nearest to the discharging location were contaminated by HCB within the range of 0.18 to 1.25 ppm. Apart from that, 1,3,5-trichlorobenzene which has never been commercially produced or used in any manufacturing processes except for the transformation from higher chlorinated benzene was also identified in the range of 0.16 to 0.24 ppm. This suggested a possibility of sporadically HCB contamination in this stream. Of more important, people in the community along this canal earn their living by coastal fishery; hence, posing a risk of spreading HCB and its less chlorinated congeners via food chain from caught marine creatures to human. As a result, there is an urgent need to understand the behavior of HCB dechlorination in this stream sediment which can lead to a clean-up action in the future. Serum bottles with sediment slurries (sediment to water ratio of 1:1 (v/v) and filtered to remove particles larger than 0.7 mm) from each site were inoculated with 2 mg/l of HCB, kept anaerobically in the dark at room temperature without any nourishment, and analyzed for HCB and its less-chlorinated congeners every 6 days. Total chemical oxygen demand, suspended solids, and volatile suspended solids were in the range of 21,492-73,584, 158,100-518,100 and 6,000-32,700 mg/l, respectively. It was found that all sediment slurries began to dechlorinate HCB in 12 to 30 days and the HCB was completely removed within 42 to 60 days or so. On the other hand, there was no HCB dechlorination occurred in the controlled set which was sterilized by autoclaving prior to the addition of HCB. This implies that the HCB transformation was solely due to microorganisms' activities. HCB was dechlorinated principally via pentachlolobenzene to 1,2,3,5-tetrachlorobenzene and terminated at 1,3,5-trichlorobenzene which is the major pathway as reported by many researchers. Dichlorobenzene has not been detected in any samples within the dechlorination period of 60 days. The results indicate that the microbial matrix in the sediment of this stream has an outstanding capability to dechlorinate HCB. Existing substrates and nutrients which mainly sorbed onto the solid phase and the typical temperature in Thailand were sufficient and suitable to promote the activities of these HCB-dechlorinating microbes.

• Korean Journal of Microbiology
• /
• v.48 no.2
• /
• pp.79-86
• /
• 2012

ErmSF is one of the Erm family proteins which catalyze S-adenosyl-$_L$-methionine dependent modification of a specific adenine residue (A2058, E. coli numbering) in bacterial 23S rRNA, thereby conferring resistance to clinically important macrolide, lincosamide and streptogramin B ($MLS_B$) antibiotics. $^{222}FXPXPXVXS^{230}$ (ErmSF numbering) sequence appears to be a consensus sequence among the Erm family. This sequence was supposed to be involved in direct interaction with the target adenine from the structural studies of Erm protein ErmC'. But in DNA methyltarnsferase M. Taq I, this interaction have been identified biochemically and from the complex structure with substrate. Arginine 223 and 227 in this sequence are not conserved among Erm proteins, but because of the basic nature of residues, it was expected to interact with RNA substrates. Two amino acid residues were replaced with Ala by site-directed mutagenesis. Two mutant proteins still maintained its activity in vivo and resistant to the antibiotic erythromycin. Compared to the wild-type ErmSF, R223A and R227A proteins retained about 50% and 88% of activity in vitro, respectively. Even though those arginine residues are not essential in the catalytic step, with their positive charge they may play an important role for RNA binding.

• Korean Journal of Ichthyology
• /
• v.8 no.1
• /
• pp.83-89
• /
• 1996

The early life history of Korean bullhead, Pseudobagrus fulvidraco was studied to obtain some information required in aquaculture and reinforcement of natural population. The fertilized eggs were almost spherical in shape and demersal. The egg membranes were transparent with minute folds on the surface, causing them to stick to other substrates. Yolk is yellowish without oil droplets. The eggs just after fertilization were measuring $1.4{\pm}0.03mm$(1.3~1.5mm, n=10) and expanded to $1.7{\pm}0.08mm$(1.6~1.8mm, n=10) in diameter in 1.5 hr. The blastodisc was formed in 30 min and cleavage started in 1 hr after fertilization, and the intervals of each stage of cleavage was about 30 min at $25.0^{\circ}C$. The yolk from 32-cell stage to gastrula stage partly depressed and the depressed part moved clockwise. Hatching occurred in 53 hr after fertilization and hatched embryos had 18~19+20~21(38~40) myomeres measuring 4.2~4.3mm in total length. At the age 7 d after hatching, 4 pairs of barbels were already formed ; 1 pair on the posterior part of the nostril, 1 pair on the upper jaw, and 2 pairs on the lower jaw. And the posterior margin of caudal fin changed into two folds. The lateral band and the form of all fins were completed in 3 weeks.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.43 no.6
• /
• pp.648-653
• /
• 2010

This study was performed to investigate the inhibitory activity of Sargassum thunbergii (ST) against ${\alpha}$-amylase and elucidate the availability of ST extract as a functional food agent. To test the inhibitory activity of ST against ${\alpha}$-amylase, porcine pancreatic ${\alpha}$-amylase and potato starch were used as substrates. It was revealed that ST crude ethanol extracts have high ${\alpha}$-amylase inhibitory activity. Subsequently, ST crude ethanol extract was separated into five partition layers by solvent extraction: n-hexane, chloroform, ethyl acetate, butanol, and water. Chloroform and n-hexane fractions showed higher inhibitory activities than did acarbose (positive control). To confirm the changes in enzyme inhibitory activity by physical treatments, ST crude ethanol extract was subjected to heat, pH, and ${\gamma}$-irradiation treatments. In all heat treatments with the exception of one ($121^{\circ}C$, 15 min), the inhibitory activity was increased compared with the untreated group. With regard to pH stability, ST extract showed no significant changes at pH 4.6, but somewhat decreased inhibitory activity was revealed at pH 2, 8, and 10. On the other hand, ST ethanol extract was stable under ${\gamma}$-irradiation under all conditions (3.20 kGy). In summary, ST ethanol extract can be used in the food industry as a natural ${\alpha}$-amylase inhibitor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.1
• /
• pp.101-112
• /
• 2015

II~VI compound semiconductors, $Zn_xCd_{1-x}S$ thin films have been synthesized onto indium-tin-oxide(ITO) coated glass substrates using thermal evaporation technique. The composition ratio x($0{\leq}x{\leq}1$) was varied to fabricate different kinds of $Zn_xCd_{1-x}S$ thin films including CdS(x=0) and ZnS(x=1) thin films. Then, the deposited thin films were thermally annealed at $400^{\circ}C$ to enhance their crystallinity. The chemical composition and electronic structure of films were investigated by using X-ray photoelectron spectroscopy(XPS). The optical energy gaps of the samples were determined by ultra violet-visible-near infrared(UV-Vis-NIR) spectroscopy and were found to vary in the range of 2.44 to 3.98 eV when x changes from 0 to 1. Finally, we measured the THz characteristics of the $Zn_xCd_{1-x}S$ thin films using THz-TDS(time domain spectroscopy) system to identify the capability for electronic and optical devices in THz region.