To find some antibacterial peptides responsible for bacterial resistance, we performed differential hybridization with total cDNA probes which synthesized from normal and immunized larvae. Thirteen individual cDNA transcripts were expressed differentially in a total 1,862 random cDNA clones. One of upregulated genes is a novel member of the insect defensin-like peptide(Coprisin), a family of antibacterial peptide. Northern blot analysis showed that Coprisin was up-regulated at 4h and reached the highest point level at 16h after injection of E.coli. The deduced amino acid sequence of Coprisin was composed of 80 amino acids with predicted molecular weight of 8.6 kDa and PI of 8.72. Comparison of the deduced amino acid mature portion of Coprisin with defensin-like peptide of other insect indicated that it has 79.1% and 67.4% identity with Anomala cuprea and Allomyrina dichotoma, respectively. To find antibacterial active region of Coprisin, we synthesized four peptides corresponding to amino acid residues 1V-43N-NH2(CopN1), 5-16(CopN2), 19-30(CopN3) and 31-43(CopN4) of coprisin having amidated amino acid residues at their Cterminal. A 12-mer amidated at its C-terminus, ACALHCIALRKK-NH2 (Ala19-Lys30-NH2) was synthesized based on the deduced amino acid sequence, assumed to be an active site sequence. This peptides showed antibacterial activity against E.coli, Staphylococcus aureus, MRSA, Psedomonas syringae, and Pectobacterium carotovorium. Modified 9-mer peptide, LRCIALRKK-NH2, showed strong antibacterial activity than mellitin peptide used as a positive control against gram-negative and gram-positive bacteria. This peptide showed no haemolytic activity and quite stable at 100℃ for several hours of incubation and in a wide pH range(pH2-12). Therefore, this peptide may be a good candidate for the development of new drug with potent antibacterial activity without cytotoxicity.

Bioaerosols become a more noticed and important problem in indoor air quality (IAQ) control. In this study, we investigated antibacterial effects of silver nano-particles on Escherichia coli, the common Gram negative bacteria and Staphylococcus aureus, the well-mown Gram positive bacteria under aerosol conditions. The bioaerosols containing each bacterial culture were contacted with silver nano-particles sprayed in a closed chamber. Experimental results showed that the silver nano-particles had strong antibacterial activity against E. coli and S. aureus, respectively. As anticipated, high antibacterial activity was found at a high silver concentration and a long the contact time. It was also found that the bactericidal rate decreased with time due to the aggregation of silver nano-particles. Overall, the experimental finding suggested that silver nano-particles could be successfully applied to improve indoor air quality.

The purpose of this study was to investigate the antibacterial effect of films on shelf-life and microbiological Safety of pork meat. Effects of antimicrobial films against total aerobic bacteria, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus in pork meat were evaluated during storage of 14 days at 5℃, 10℃ and 15℃. Antimicrobial films were developed with addition of a natural substance, wasabi extracts (Wasabia japonica). At 5℃ storage, growth of total aerobic bacteria, E. coli O157:H7, L. monocytogenes were inhibited higher than at 10 and 15℃. Especially, the numbers of S. Typhimurium and S. aureus were increased gradually at 5℃ even in the control sample, and it takes more than 14 days to increase in every sample upto 6 log10 cfu/g. The higher antimicrobial effects of the films were observed at storage of 5℃ than at 10oC and 15℃. There was a limit of a single treatment of antimicrobial film to prolong shelf-life of pork meat. The synergistic effect of antimicrobial film were observed with addition of refrigeration at 5℃.

The insect baculovirus expression vector system (BEVS) is useful for the production of biologically active recombinant proteins. However, the overexpression of foreign proteins in this system often results in misfolded proteins and the formation of protein aggregates. To overcome this limitation, we have developed a versatile baculovirus expression and secretion system using the Bombyx mori protein disulfide isomerase (bPDI) as a fusion partner. bPDI gene fusion improved the secretion and antibacterial activity of recombinant nuecin proteins. Thus, bPDI gene fusion is a useful addition to the BEVS for the large-scale production of bioactive recombinant proteins.

새로운 항균물질의 탐색이 활발하다. 선행연구에서 새로운 항균활성물질을 생산하는 세균이 한국토양에서 분리되어 Paenibacillus polymyxa DY1으로 동정 및 명명되었으며, 다제내성 장내세균들에 대한 항균활성 특성이 규명되어 새로운 항생물질로서 잠재력을 보여주었다. 본 연구에서 배지의 탄소원, 무기질소원, 유기질소원, 아미노산, 무기염류 등의 영양 조성물과 물리화학적 생장조건이 P. polymyxa DY1 균체의 생장과 항균활성 생산에 미치는

동결 건조된 죽력을 물 또는 50% ethanol에 각각 용해시킨 시료(1 mg eq./disc)에 대하여 항세균 활성을 측정한 결과, 물에 용해시킨 죽력은 gram 양성균의 경우 L. monocytogenes이 15 mm의 저해환으로 가장 활성이 강하였고 B. subtilis는 활성이 전혀 나타나지 않았으며 Gram 음성균의 경우는 S. dysenteriae가 저해환이 22 mm로 가장 강한 활성을 보였다. 50% ethanol에 용해시킨 죽력은 gram 양성균의 경우 L. monocytodenes, 가 가장 강한 활성을 보였으나 B. subtilis는 활성이 전혀 없던 물에 용해시킨 경우에 비하여 활성이 크게 나타났다. Gram 음성균의 경우, S. dysenteriae가 23 mm저해 환으로 가장 강한 활성을 보였고 V. parahaemolyticus, V. vulnificus, E. coli O157:H7는 16 mm로 상대적으로 약한 활성을 보였다. 젖산균 2종의 경우는 물 또는 50% ethanol에 용해시킨 경우 모두 전혀 활성을 나타내지 않았다. 최소저해농도는 L. monocytogenes는 50% ethanol에 녹인 경우 MIC가 0.6 mg/disc로 가장 낮았고 물에 용해시킨 죽력의 경우 S. epidermides, S. dysenteriae, L. monocytogenes, Sal. typhimurium, V. parahaemolyticus가 각각 0.8 mg/disc의 MIC값을 나타내 50% ethanol에 용해시킨 경우에 비하여 MIC값이 높은 경향을 보였으며 다른 세균들은 1.0 mg/disc의 거의 유사한 MIC값을 보였다. Model food system에서의 저해활성은 물에 용해시킨 죽력 보다 50%, ethanol에 용해시킨 죽력이 대조구에 비하여 생육을 강하게 저해하였고 MIC가 낮은 이들 4가지 공시균주들이 모두 model food system상에서 상당히 강한 저해활성을 나타내 50% ethanol에 용해시킨 죽력은 적절한 농도에서 부패세균들의 생육 억제제로 사용 가능할 것으로 사료되었다.

Antibacterial behaviors of PAN-based activated carbon fibers (ACFs) containing silver metal were investigated. The effects of surface and pore structures of the ACFs were studied by N2/77 K adsorption and D-R plot as a function of silver loading content. The antibacterial activities were investigated by a dilution test against Staphylococcus aureus (S. aureus; gram positive) and Klebsiella pnemoniae (K. pnumoniae; gram negative). As experimental results, the ACFs showed some decreases in specific surface areas, micropore volumes, and total pore volume with an increase of silver content. However, the antibacterial activities of the ACFs were strongly increased against S. aureus as well as K. pnumoniae, which could be attributed to the presence of antibacterial metal in the ACFs system.

For the austenitic stainless steel (304L) manufactured by metal injection molding(MIM), the effects of copper content and sintering temperature on the mechanical properties, antibacterial activities, corrosion resistance, and electric resistances were investigated. The specimens were prepared by injection molding of the premixed powders of water-atomized 304 L and Cu with poly-acetyl binders. The green compacts were prepared with various copper contents from 0 to 10 wt.% Cu, which were debound thermally at 873 K for 7.2 ks in gas atmosphere and subsequently sintered at various temperatures from 1323 K to 1623 K for 7.2 ks in Ar gas atmosphere. The relative density and tensile strength of the sintered compacts showed the minimum values at 5 and 8 wt.% Cu, respectively. Both the relative density and the tensile strength of the specimen with 10 wt.% Cu sintered at 1373 K showed the highest values, higher than those of copper-free specimen. Antibacterial activities investigated by the plastic film contact printing method for bacilli and the quantitative analysis of copper ion dissolved in water increased as the increase of the copper content to stainless steels. It was also verified by the measurement of pitting potential that the copper addition in 304 L could improve the corrosion resistance. Furthermore the electric conductivity increased with the increase of copper content.

Antibacterial activities in each part of watercress(Oenanthe javanica D.C.) grown under different culture conditions were measured to determine the possibility to use watercress as a resource to develop the antibacterial substance. The leaves of watercress were extracted with methanol and the methanol extract was further fractionated with various organic solvents. Antibacterial activities against Shigella dysenteriae ATCC 9361 in all fractions were determined according to the agar diffusion method using paper disc. Methanol extract of watercress leaves was more effectively inhibited the growth of the tested bacteria than the extracts of roots or stems at the concentration of 0.5 g eq./disc, and the extract of watercress from Hwasoon was the most effective one as compared to others. Phenolic and neutral fractions fractionated from methanol extract of watercress had a considerable inhibiting activity on the growth of the bacteria, but acidic and basic fractions did not show any inhibitory effect. Minimum inhibitory concentrations of phenolic and neutral fractions against Shigella dysenteriae ATCC 9361 were 400 μg/disc and 550 μg/disc, respectively.

Agar, one of the most abundant marine products has not been utilized extensively because of low level of processing technology in Korea. This research was carried out to improve the utilization of agar and consequent increase in profit. Antibacterial activity of agarooligosaccharides were evaluated against bacteria causing putrefaction and food poisoning. Addition of 0.4% agarooligosaccharides showed antibacterial activity toward Staphylococcus aureus and Escherichia coli O157:H7; furthermore, autoclave treatment of agarooligosaccharides solution enhanced the antibacterial activity. Agarooligosaccharides showed high stability against the pH change. Addition of amino acid(alanine, lysine, glycine, phenylalanine) in agarooligosaccharides solution enhanced antibacterial activity in E. coli O157:H7, Streptococcus mutans and Staphylococcus aureus.