• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.281-286
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• 2010

A Pseudomonas fluorescens strain was isolated and found to show antagonistic activity against phytopathogenic fungi and to possess a gene responsible for production of antibiotic 2,4-diacetylphloroglucinol. For the extension of biocontrol range, a gene for an Androetonus australis Hector insect toxin 1 (AaHIT1), one of the most known toxic insect-selective peptides, was designed and synthesized according to the preferred codon usage of Pseudomonas fluorescens, cloned, and transformed into the strain by pSUP106 vector, a broad-host-range plasmid. Bioassays indicated that the engineered strain was able to produce AaHIT1 with insecticidal activity, and at the same time retain the activity against plant pathogen. The experiments for nonplanted soil and rhizosphere colonization showed that, similar to the population of the wild-type strain, that of the engineered strain remained relatively constant in the first 10 days, and the subsequent 50 days, suggesting that AaHIT1 expression in the bacterial cell does not substantially impair its long-term colonization. It is first reported that a Pseudomonas fluorescens strain expressing an active scorpion neurotoxin has dual activity against phytopathogenic fungi and insects, making at attractive for agronomic applications.

• Ocean and Polar Research
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• v.41 no.4
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• pp.289-309
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• 2019

Marine microalgae have long been used as food additives and feeds for juvenile fish and invertebrates as their nutritional content is beneficial for humans and marine aquaculture species. Recently, they have also been recognized as a promising source for cosmeceutical, nutraceutical, and pharmaceutical products as well as biofuels. Marine microalgae of various species are rich in multiple anti-oxidant phytochemicals and their bioactive components have been employed in cosmetics and dietary supplements. Oil contents in certain groups of marine microalgae are extraordinarily rich and abundant and therefore have been commercialized as omega-3 and omega-6 fatty acid supplements and mass production of microalgae-based biodiesels has been demonstrated by diverse research groups. Numerous natural products from marine microalgae with significant biological activities are reported yearly and this is attributed to their unique adaptive abilities to the great diversity of marine habitats and harsh conditions of marine environments. Previously unknown toxin compounds from red tide-forming dinoflagellates have also been identified which opens up potential applications in the blue biotechnology sector. This review paper provides a brief overview of the biotechnological potentials of Korean marine microalgae. We hope that this review will provide guidance for future marine biotechnology R&D strategies and the various marine microalgae-based industries in Korea.

• Journal of Dairy Science and Biotechnology
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• v.33 no.1
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• pp.59-67
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• 2015

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is well-characterized as an important food-borne pathogen worldwide and causes human diseases such as diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS) by producing shiga-like toxin (Stx). It has been reported that a number of dairy foods, including cheese, can act as the source of EHEC O157:H7 infections. In addition to the toxicity of Stx, recently it has been indicated that EHEC O157:H7 possesses virulence factors related to attachment, quorum sensing, and biofilms. Moreover, these novel virulence factors might become critical points to be considered in the future production of food derived from animals. Here, we review the evidences that support these insights on new virulence factors and discuss the potential mechanisms mediating the pathogenesis of EHEC O157:H7 in the dairy food industry.

• Molecular & Cellular Toxicology
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• v.5 no.3
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• pp.230-236
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• 2009

Acrolein, a known toxin in cigarette smoke, is the most abundant electrophilic $\alpha$, $\beta$-unsaturated aldehyde to which humans are exposed in a variety of environmental pollutants, and is also product of lipid peroxidation. Increased unsaturated aldehyde levels and reduced antioxidant status plays a major role in the pathogenesis of various diseases such as diabetes, Alzheimer's and atherosclerosis. The findings reported here show that low concentrations of acrolein induce heme oxygenase-1 (HO-1) expression in RAW 264.7 macrophages. HO-1 induction by acrolein and signal pathways was measured using reverse transcription-polymerase chain reaction, Western blot and immunofluorescence staining analyses. Inhibition of extracellular signal-regulated kinase activity significantly attenuated the induction of HO-1 protein by acrolein, while suppression of Jun N-terminal kinase and p38 activity did not affect induction of HO-1 expression. Moreover, rottlerin, an inhibitor of protein kinase $\delta$, suppressed the upregulation of HO-1 protein production, possibly involving the interaction of NF-E2-related factor 2 (Nrf2), which has a key role as a HO-1 transcription factor. Acrolein elevated the nuclear translocation of Nrf2 in nuclear extraction. The results suggest that RAW 264.7 may protect against acrolein-mediated cellular damage via the upregulation of HO-1, which is an adaptive response to oxidative stress.

• Korean Journal of Veterinary Research
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• v.39 no.5
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• pp.995-1005
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• 1999

Staphylococcus aureus is one of most prevalent intramammary pathogens and have characteristics which are not easily eradicated. Recently, to understand the sources and transmission of S aureus, many studies have focused on the subtyping of field isolate. This study was preformed to investigate the distribution pattern and characteristics of the isolates using phenotyping and genotyping. Samples were collected from milk of each udder, cow bodies (perianal region, vagina, tail, udder skin, sole) and environment (floor, liner, milker's hands, water, towel, insect) from 6 herds located in Kyung-gi province. Forty five strains of S aureus were isolated from 3 dairy herds (A, B, C) and were typed by hemolytic pattern, antibiotic resistant pattern, enterotoxin typing and PCR-based DNA fingerprinting. Slime productivity was also compared by each subtype to examine potential infectiousness. Of 45 strains, 41 were isolated from milk samples and 4 were isolated from liners. No strains isolated in the bodies and environment. Forty five strains isolated were classified as 18 subtypes by phenotyping and genotyping. There was common subtype between A and B herd, but the subtype of C herd showed different pattern. Among predominant subtypes, 60% of S aureus strain isolated from A and B herd showed subtype I and 50% of S aureus strain isolated from C herd belonged to subtype VI and X II. Neither somatic cell count (SCC) nor slime production was significantly different between predominant and minor subtypes. In summary, the study revealed that liners play more important roles in the mode of transmission than environmental sources. Several subtypes can be found in a herd, only a few subtype, however, was largely associated with the majority of infection.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.1
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• pp.127-130
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• 2004

Lathyrus sativus, locally known as Khesari, is a leguminous pulse crop grown in many parts of the world for food (used by poor people) and animal feed/fodder. Its seeds are rich in protein and energy but contains anti-nutritional factors prominent among which is ${\beta}$-N-Oxalylamino-L-Alanine (BOAA), a neurotoxin causing lathyrism in humans due to prolong consumption. Keeping in view the chemical characteristics of this toxin and literary facts on L. sativus feeding in terrestrial animals, it was hypothesized that aquatic species may better utilise this ingredient in mixed extruded diets. Diets were prepared with varying levels (0, 10, 18, 26 and 34%) of L. sativus seeds and fed for 60 days to study growth, body composition and digestibility of nutrients. Final body weight, specific growth rate and feed and protein conversion ratio did not differ (p>0.05) between treatments. Crude protein digestibility was reduced (p<0.01) beyond 26% inclusion level of L. sativus. Final carcass composition with regard to protein, lipid and ash did not differ (p>0.05) among the treatments. Comparable craniosomatic, viscerosomatic, renosomatic and hepatic indices and no mortality implies no apparent adverse effect on the vital organs and fish health. It was concluded that L. sativus can be a promising feed ingredient that can be used up to 34% or possibly higher level in fingerlings diet. To our knowledge, it appears to be the first report of its kind under laboratory conditions.

• Korean Journal of Microbiology
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• v.46 no.4
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• pp.389-396
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• 2010

Insecticidal crystalline toxin producing Bacillus thuringiensis BT17 strain was isolated and identified as B. thuringiensis serovar colmeri by 16S rRNA analysis. BT17 strain produced crystalline ${\delta}$-endotoxin against to Lepidopteran larvae effectively on the culture broth of soybean meal and skim milk, $30^{\circ}C$ and 36 h shaking culture of 280 rpm. The maximum colony forming unit achieved when the culture was continued for 24 h, but the number of crystals increased until 36 h in the 200 L fermentor. Liquid type of biological insecticide product was made, and after 3 months storage in $20^{\circ}C$ the number of crystals was increased up to twice than beginning. Biocontrol effect of BT17 insecticide product was better in Plutella xylostella than in Spodoptera exigua, and the toxicity to animals was negligible.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.108-114
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• 2015

Curvularia lunata is an important maize foliar fungal pathogen that distributes widely in maize growing area in China, and several key pathogenic factors have been isolated. An yeast two-hybrid (Y2H) library is a very useful platform to further unravel novel pathogenic factors in C. lunata. To construct a high-quality full length-expression cDNA library from the C. lunata for application to pathogenesis-related protein-protein interaction screening, total RNA was extracted. The SMART (Switching Mechanism At 5' end of the RNA Transcript) technique was used for cDNA synthesis. Double-stranded cDNA was ligated into the pGADT7-Rec vector with Herring Testes Carrier DNA using homologous recombination method. The ligation mixture was transformed into competent yeast AH109 cells to construct the primary cDNA library. Eventually, a high qualitative library was successfully established according to an evaluation on quality. The transformation efficiency was about $6.39{\times}10^5$ transformants/$3{\mu}g$ pGADT7-Rec. The titer of the primary cDNA library was $2.5{\times}10^8cfu/mL$. The numbers for the cDNA library was $2.46{\times}10^5$. Randomly picked clones show that the recombination rate was 88.24%. Gel electrophoresis results indicated that the fragments ranged from 0.4 kb to 3.0 kb. Melanin synthesis protein Brn1 (1,3,8-hydroxynaphthalene reductase) was used as a "bait" to test the sufficiency of the Y2H library. As a result, a cDNA clone encoding VelB protein that was known to be involved in the regulation of diverse cellular processes, including control of secondary metabolism containing melanin and toxin production in many filamentous fungi was identified. Further study on the exact role of the VelB gene is underway.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.251-257
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• 2004

This study was designed to determine optimal condition for expression of cloned Shigatoxin2e(Stx2e) gene from transformed E. coli PED18, to compare the cytotoxicity titer between cloned Stx2e and Stx2e from original strain, and to confirm of receptor binding affinity of Stx2e for use of development of receptor binding ELISA to detect of Stx2e. The optimum composition of medium for expression of Stx2e gene in E.coli host-vector system was definded as the medium containing 0.5% glucose and 0.5 mM IPTG. The cytotoxicity titer of expressed Stx2e for Vero cell was 1000 fold higher than that of Stx2e from original strain AY93258. The binding affinity of Stx2e to receptor globotetraosyl ceramide($Gb_4$) was confirmed by immunobloting.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.16-28
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• 2018

Although physiological and ecological characteristics of cyanobacteria have been studied extensively for decades, unknown areas still remain greater than the already known. Recently, the development of omics techniques based on molecular biology has made it possible to view the ecosystem from a new and holistic perspective. The molecular mechanism of toxin production is being widely investigated, by comparative genomics and the transcriptomic studies. Biological interaction between bacteria and cyanobacteria is also explored: how their interactions and genetic biodiversity change depending on seasons and environmental factors, and how these interactions finally affect each component of ecosystem. Bioinformatics techniques have combined with ecoinformatics and omics data, enabling us to understand the underlying complex mechanisms of ecosystems. Particularly omics started to provide a whole picture of biological responses, occurring from all layers of hierarchical processes from DNA to metabolites. The expectation is growing further that algal blooms could be controlled more effectively in the near future. And an important insight for the successful bloom control would come from a novel blueprint drawn by omics studies.