• Food Science and Biotechnology
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• 제14권1호
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• pp.32-38
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• 2005

Effects of acid and ${\alpha}$-amylase on resistant starches including retrograded RS3 and cross-linked RS4 prepared from normal maize starch were investigated. Acid and ${\alpha}$-amylase hydrolytic patterns of RS3 were similar, while those of native starch and RS4 differed. Acid hydrolysis rate of RS3 was markedly higher at initial stage, then slowly decreased up to 20 days, whereas that of RS4 increased continuously. The sizes of acid- and ${\alpha}$-amylase-treated RS3 residues decreased, but those of RS4 remained unchanged. X-ray patterns of all treated residues did not change; however, the peak intensities increased. Swelling power of RS3 increased to 150% at $95^{\circ}C$, whereas that of RS4 differed depending on the treatment condition. Swelling power of acid-treated RS4 residue increased markedly, but that of ${\alpha}$-amylase-treated one remained constant. Gel filtration chromatography profiles of untreated RS3 and RS4 residues were similar, whereas that of acid-treated RS4 residue was different from them. RS showed different hydrolytic behavior by acid and ${\alpha}$-amylase depending on the type, and susceptibility of RS3 was higher than that of RS4.

• 멤브레인
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• 제16권3호
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• pp.230-234
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• 2006

본 연구는 산저항성을 가진 새로운 폴리비닐알콜계 투과증발막을 이용한 불화에탄올(TFEA)과 메타크릴산(MA)의 에스테르화 반응에 관한 연구이다. TFEA와 MA의 에스테르화 에스텔화반응에 사용된 폴리비닐알콜계 막은 PVA와 EGDE의 열 가교반응을 통하여 제조되었다. 에스텔화 반응의 반응조건 - 반응온도, 산 촉매의 양, 초기 몰비(불화에탄올/메탄크릴산)- 등을 달리하여 에스텔화 반응에 미치는 영향을 조사하였다. 실험 결과, TFEMA 전환율은 반응온도 촉매의 양, 초기몰비가 증가함에 따라 향상되었다. TFEMA 전환율이 90% 이상을 위한 경제적인 반응조건은 $90^{\circ}C$의 반응온도, 2.5 wt%의 촉매 양, 그리고 1.7의 초기 반응 몰비였다.

• 미생물학회지
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• 제48권3호
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• pp.212-215
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• 2012

Ursolic acid (UA)와 oleanolic acid (OA)들의 메티실린 저항성 Staphylococcus aureus (MRSA)에 대한 항균 활성에는 상반된 의견들이 있다. 본 연구는 한국인으로부터 분리된 19개의 MRSA에 대한 UA와 OA의 항균 활성을 최소성장억제농도 및 최소살균농도를 측정하여 조사하였다. 연구 결과, 메티실린 감수성 균주인 S. aureus KCTC $1621^T$가 MRSA 균주들보다 UA와 OA에 대한 저항성이 컸다. UA와 OA 각각의 MRSA 19 균주에 대한 최소살균농도는 4-32 ${\mu}g/ml$와 16->256 ${\mu}g/ml$로 넓은 범위를 보였다. UA와 OA에 대한 균주에 따른 항균 작용의 차이는 UA와 OA의 항균 기전이 밝혀져 있지 않기 때문에 이해하기 힘들다. 이러한 결과들은 MRSA에 대한 UA와 OA의 항균 효과는 균주들 간의 UA와 OA에 대한 저항 능력에 의한 것임을 시사한다.

• 미생물학회지
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• 제50권3호
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• pp.185-190
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• 2014

원유시료에서 분리한 대장균의 quinolone 항생제 내성비율과 그 내성 결정인자를 분석하였다. 원유시료에서 대장균을 분리하고 quinolone 항생제인 nalidixic acid와 ciprofloxacin에 대한 MIC값을 결정하였으며 내성균을 대상으로 염색체상에 있는 quinolone 내성 결정부위(quinolone resistant determining region, QRDR)인 gyrA, gyrB, parC, pareE의 염기서열 분석, 플라스미드상에 존재하는 내성유전자(plasmid mediated quinolone resistant, PMQR) qnrA, qnrB, qnrS, aac(6')-lb-cr, qepA의 분석 및 약물 유출펌프 유전자인 acrB의 발현을 비교 분석하였다. 그 결과 총 487개의 대장균군 세균중 9개의 균이 nalidixic acid에 내성임을 확인하였으며($MIC{\geq}64{\mu}g/ml$) 이중 6개 균주가 ciprofloxacin에도 내성임을 확인하였다(MIC $4-16{\mu}g/ml$)). 9개의 내성 균주 모두 QRDR의 gyrA 영역 codon 83에 변이(S83L)를 갖고 있었으며 그 중 2균주는 codon 83과 87 (S83L and D87N)에 이중 돌연변이를 갖고 있었다. 한편 9균주 중 3개의 균주에서 parC 영역 codon 80 (S80I)에 변이를 갖고 있었다. 플라스미드 상에 존재하는 내성유전자인 qnrA, qnrB, qnrS, aac(6')-lb-cr 및 qepA 유전자는 존재하지 않았으며 AcrAB-TolC efflux pump 유전자인 acrB 유전자가 대조균인 E. coli ATCC 25922와 비교하여 ciprofloxacin 내성 균주 6균주 중 4균주에서 유의적으로 과발현(2.15-5.74배) 되고 있음을 확인하였다.

• The Plant Pathology Journal
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• 제38권1호
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• pp.25-32
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• 2022

Plant pathogens pose major threats on agriculture and horticulture, causing significant economic loss worldwide. Due to the continuous and excessive use of synthetic pesticides, emergence of pesticide resistant pathogens has become more frequent. Thus, there is a growing needs for environmentally-friendly and selective antimicrobial agents with a novel mode of action, which may be used in combination with conventional pesticides to delay development of pesticide resistance. In this study, we evaluated the potentials of lichen substances as novel biopesticides against eight bacterial and twelve fungal plant pathogens that have historically caused significant phytopathological problems in South Korea. Eight lichen substances of diverse chemical origins were extracted from axenic culture or dried specimen, and further purified for comparative analysis of their antimicrobial properties. Usnic acid and vulpinic acid exhibited strong antibacterial activities against Clavibacter michiganensis subsp. michiganensis. In addition, usnic acid and vulpinic acid were highly effective in the growth inhibition of fungal pathogens, such as Diaporthe eres, D. actinidiae, and Sclerotinia sclerotiorum. Intriguingly, the growth of Rhizoctonia solani was specifically inhibited by lecanoric acid, indicating that lichen substances exhibit some degrees of selectivity to plant pathogens. These results suggested that lichen substance can be used as a selective biopesticide for controlling plant disease of agricultural and horticultural significance, minimizing possible emergence of pesticide resistant pathogens in fields.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.11-12
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• 2015

This study analyzed sulfate resistance of strongly acid-resistant inorganic binder based on industrial byproducts. According to the study experiment, compared to OPC mixture, the mixture of high acid-resistant inorganic binder had excellent chemical resistance against 10% H₂SO₄ solution. In the case of ordinary portland cement, its sample with 28 days of immersion had severe corrosion on its mortar erosion part, and thus external appearance was damaged greatly, and compression strength decreased by around 57% and more.

• 약학회지
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• 제39권6호
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• pp.676-680
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• 1995

The nucleotide sequence of Xbal-Mbol fragment of pKH7, a chloramphenicol-resistant($Cm^{r}$) plasmid isolated from multidrug-resistant S. aureus SA2, has been determined. Xbal-Mbol fragment of pKH7 was found to contain two ORFs. One ORF encoded Rap and the other encoded CAT protein. The deduced amino acid sequences of Rep and CAT of pKH7 were compared to those of pUB112 and pC221. Comparisons revealed that there was one amino acid difference in CAT between pKH7 and pUB112. CAT of pKH7 exhibited 98.6% amino acid identity to that of pC221. In case of Rep proteins, a slightly lower homology of 96.4% and 86.7% in amino acid sequences was observed between pKH7 and pUB112 and between pKH7 and pC221, respectively.

• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.104-110
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• 2006

We investigated why aspen extractives are more resistant in kraft pulping than pine extractives. Residual extractives content in aspen kraft pulps were 0.5~1.1% compared with 0.1~0.2% in pine pulps. This different response arises from the different composition of extractives in wood chips. Resin acids in pine were almost completely removed in kraft pulping but those are not existence in aspen. Slower saponification of aspen steryl esters resulted from different chemical structure of aspen steryl esters. Main sterols in aspen steryl esters were 24-methyl cyclolanostenol which was highly resistant to alkaline hydrolysis with its characteristic steric hindrance. Sterols in aspen were not well removed in kraft pulping. The relative composition of sterol in aspen kraft pulps was increased with increasing pulping time. The presence of fatty acids in aspen kraft pulps is considered to unusual. Fatty acids in alkaline are supposed to be well ionized and removed well in the washing stage. Nevertheless, there were significant amount of fatty acids remaining in aspen kraft pulps.

• 한국작물학회지
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• 제68권3호
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• pp.175-187
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• 2023

Peanuts, also known as groundnuts (Arachis hypogaea L.), are globally recognized as a vital oilseed crop. Peanuts are rich in proteins (e.g., arginine), oils (e.g., oleic acid and linoleic acid), fiber, vitamins (e.g., niacin and tocopherol), and carbohydrates and are consumed worldwide. However, the presence of aflatoxin (AF) has garnered substantial attention since its initial discovery as the causative agent of Tukey's X disease in the United Kingdom in 1960. Among the 18 aflatoxins identified, aflatoxin B₁ (AFB₁) has the highest toxic activity and causes hepatocellular carcinoma. It is classified as Group I by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). The present study was conducted to evaluate aflatoxin B₁ resistance of 102 peanut accessions and select putative aflatoxin B₁-resistant peanut accessions to aflatoxin B₁. One hundred and one Korean germplasms harvested in 2020 were inoculated with A. flavus to identify aflatoxin-resistant cultivars, and the aflatoxin B₁ concentration was measured using an ultra-performance liquid chromatography-photodiode array detector. Twenty-six accessions with aflatoxin B₁ concentrations lower than those of the check plant 55-437 were chosen for the development of aflatoxin-resistant varieties in Korea. As Korean aflatoxin-resistant varieties have not yet been developed, the findings of the present study are expected to provide useful information for the development of aflatoxin-resistant cultivars.

• 한국미생물·생명공학회지
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• 제30권2호
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• pp.129-134
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• 2002

토종닭 소장으로부터 가축 소화기 병원성 유해세균의 분리를 위하여 무작위 선별법과 중층-도말법을 사용하여 총130주의 유산균을 1차 분리하였다. 1차 분리한 130주를 paper disc법을 사용하여 최종적으로 살모넬라 균, 포도상구균, 대장균에 대하여 저해능이 우수한 7주를 분리하였다. 분리 균주의 동정을 위하여 1차로 API CHL kit를 사용하였고, 동정의 정확성을 높이기 위하여 2차로 16S rRNA sequencing 방법을 사용하였다. 그 결과 BD14 균주는 Pediococcus pentosaceus로 동정되었으며 나머지 6주는 Lactobacillus sp.로 동정되어 모두 안전성 있는 유산균임을 확인하였다. 여러 병원균에 가장 항균력이 큰 유산균은 L. pentosus K34이었으며, 이 유산균은 염산과 담즙산에 대한 내성에서도 가장 우수한 균주로 나타났다. 10종의 항생제에 대한 감수성을 조사한 결과 ciprofloxacin에 대하여 모든 균주가 내성을 보였고, BL 균주를 제외하고 모든 균주가 colistin, streptomycin에 대하여 내성을 보였다. 또한 BD14, BD16, K34 균주가 gentamicin에 대한 내성을 보였다.