미생물의 탈염소화 작용에 의한 남분해성 염화방향족 오염물질의 분해

채종찬,김치경 한국환경생물학회 1999 환경생물 : 환경생물학회지 Vol.17 No.2

난분해성 유기화합물의 일종인 염화 방향족화합물은 냉각제, 소화제, 페인트, 용매, 플라스틱류, 유압제, 제초제, 농약, 그리고 화학합성에 필요한 전구물질 등에 널리 사용된다. 이들은 친지질 특성을 가지므로 생물체의 세포막에 쉽게 흡착되며 먹이사슬에 의한 생물학적 농축과정을 통해 인간을 포함하는 각종 생물체에 축적된다. 그 결과 생물체의 세포막 구조가 변화되고 기능이 저해될 뿐더러 암과 돌연변이를 유발하고 「환경호르몬」으로서 생물체의 내분비게 기능을 교란하는 등 심각한 보건학적 그리고 환경생물학적 문제를 일으키고 있다. 염화 방향족화합물들은 벤젠고리 구조와 벤젠고리에 염소가 치환된 탄소-염소 결합을 공통적으로 가지고 있으며 벤젠고리에 치환된 염소의 수와 같은 수의 염소라도 붙어 있는 위치에 따라 난분해 특징이 결정된다. 염화 방향족화합물들의 분해를 위해서는 미생물에 의한 벤젠 구조의 개환과정과 함께 벤젠 고리구조로부터 염소 치환기를 제거하는 탈염소황 과정이 반드시 일어나야만 한다. 호기적 환경에서 미생물에 의한 탈염소화는 분해 초기단계에서 dehalogenase라는 효소에 의해 촉매되는 oxygenolytic, reductive, 그리고 hydrolytic catalysis에 의해 일어나거나, 분해 대사과정 중에 저절로 염소치환기가 떨어져 나가는 경우도 있다. 탈염소화 과정을 거쳐 분해하는 미생물들을 이용한 염솨 방향족 오염물질의 생물학적 분해방법은 이미 사용되고 있는 물리·화학적 방법보다 경제적이며 2차 오염의 부작용 없이 그 오염물질들을 매우 효과적으로 처리할 수 있다. 따라서 탈염소화 기작을 포함한 분해과정의 이해는 생물학적 분해의 기본적인 정보를 제공할 뿐더러 난분해성 환경 오염물질의 분해처리를 위하여 보다 집중적으로 연구해야 할 과제라고 할 것이다. Chlorinated aromatic compounds are one of the largest groups of environmental pollutants as a result of world-wide distribution by using them as herbicides, insecticides, fungicides, solvents, hydraulic and heat transfer fluids, plasticizers, and intermediates for chemical synthesis. Because of their toxicity, persistence, and bioaccumulation, the compounds contaminated ubiquitously in the biosphere has attracted public concerns in terms of serious influences to wild lives and a human being, such as carcinogenicity, mutagenicity, and disturbance in endocrine systems. The biological recalcitrance of the compounds is caused by the number, type, and position of the chlorine substituents as well as by their aromatic structures. In general, the carbon-halogen bonds increase the recalcitrance by increasing electronegativity of the substituent, so that the dechlorination of the compounds is focused as an important mechanism for biodegradation of chlorinated aromatics, along with the cleavage of aromatic rings. The removal of the chlorine substituents has been known as a key step for degradation of chlorinated aromatic compounds under aerobic condition. This can occur as an initial step via oxygenolytic, reductive, and hydrolytic mechanisms. The studies on the biochemistry and genetics about microbial dechlorination give use the potential informations for microbial degradation of xenobiotics contaminated in natural microcosms. Such investigations might provide biotechnological approaches to solve the environmental contamination, such as designing effective bioremediation systems using geneticallly engineered microorganisms.

Mean Field Annealing을 이용한 전문가 시스템의 구현

최채택,이종찬,이원돈 충남대학교 1990 忠南科學硏究誌 Vol.17 No.2

Mean Field Annealing(MFA), which is an analytic version of Stochastic Simulated Annealing(SSA), is explored with its application as well as its theoretical background. In this paper, we used MFA to optimize Harmonium, a two level Neural Network Model. We concluded that MFA is faster and more stationary than SSA.

솔잎혹파리 피해임지의 수세변동에 관한 연구

이찬용,채희문,김종국 강원대학교 삼림과학연구소 2000 Journal of Forest Science Vol.16 No.-

솔잎혹파리 피해임지의 특성에 따른 수세변동을 구명하였다. 솔잎혹파리 피해도(「심), 「중), 「경))별로 구분하여 수세를 조사한 결과 피해가 심한 지역의 수목은 수세가 현저하게 약화되었으며, 수목의 임분밀도(「밀), 「중),「소」)별로 구분한 경우는 피해도와 관계없이 임분밀도가 낮은 임분에서 수목의 수세가 강하게 나타났다. 수목의 외형적 인자중 수관폭과, 흉고직경이 작은 개체에 비하여 큰 개체의 수세가 모든 임분에서 강하게 나타났다. 각 임분에서 전기저항치와 수관면적과의 관계는 피해도 「심」 임분에서는 수관면적이 13.4m2, 「중」 임분에서는 10.9m2, 「경」 임분에서는 7.9m2로 피해가 심할수록 수관면적이 넓어야 임목이 생존할 가능성이 높은 전기저항치(15kΩ이하)가 나타나는 것으로 파악되었다. This study investigated tree vigor of damaged forest by Thecodiplosis japonensis Uchida et Inouye. In damaged forest by pine gall midge, the investigation result of damaged rate section(severe, moderate, light) indicated that severe stand showed higher value of electric resistance(kΩ) than that of light stand, the investigation result of tree density section(crowed, middle, little) indicated that crowed stand showed higher value of electric resistance than that of little stand(the value of electric resistance at which low reading show high vigor tree and high reading low vigor tree). The crown width and DBH(diameter of breast height) of external factors showed lower value of electric resistance than that of small size. The results of comparative between Crown area and value of electric resistance in each stand were 13.4m2 in severe stand, 10.9m2 in moderate stand and 7.9m2 in light stand. Therefore, the tree which have big crown showed low value of electric resistance(below 15kΩ)that has high possible of survial. Key word : Thecodiplosis japonensis, electric resistance, crown area

Cross Hole Type 비 연삭 밀링 인서트의 가공특성에 관한 연구

김택수,이상민,박휘근,채승수,이충석,손일복,김학규,이종찬 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

This paper reports some experimental results on the machining performance of non-ground cross hole type milling inserts. Six kinds of milling inserts were manufactured without using grinding process. Machining experiments were carried out to compare the machining performance of non-ground inserts with that of ground ones. The experimental results indicate that the cutting forces and surface roughnesses of machined surface of both ground and non-ground inserts are comparable.

Dechlorination of 4-Chlorobenzoate by Pseudomonas sp. DJ-12

Chae, Jong-Chan,Kim, Chi-Kyung The Microbiological Society of Korea 1997 The journal of microbiology Vol.35 No.4

4-Chlorobiphenyl-degrading Pseudomonas sp. DJ-12 was able to degrade 4-chlorobenzoate(4CBA), 4-iodobenzoate, and 4-bromobenzoate completely under aerobic conditions. During. the degradation of 4CBA by Pseudomonas sp. DJ-12, chloride ions were released by dechlorination and 4-hydroxybenzoate was produced as an intermediate metabolite. The NotI-KNA fragments of pKC157 containing dechlorination genes hybridized with the gene encoding 4CBA:CoA dehalogenase of Pseudomonas sp. CBS3 which is responsible for the hydrolytic dechlorination of 4CBA. These results imply that Pseudomonas sp. DJ-12 degrades 4CBA to 40hydroxybenzoate via dechlorination as the initial step of its degradativ pathway. The genes responsible for dechlorination of 4CBA were found to be blcated on the chromosomal DNA of Pseudomonas sp. DJ-12.

Cloning and Sequencing of the fcbB Gene Encoding 4-Chlorobenzoate-Coenzyme A Dehalogenase from Pseudimonas sp. DJ-12

Chae, Jong-Chan,Kim, Youngsoo,Min, Kyung-Hee,Kim, Young-Change,Kim, Chi-Kyung Korean Society of Molecular Biology 1999 Molecules and cells Vol.9 No.2

Catabolic Degradation of 4-Chlorobiphenyl by Pseudomonas sp. DJ-12 via Consecutive Reaction of meta-Cleavage and Hydrolytic Dechlorination

Chae, Jong-Chan,Kim, Eunheui,Park, Sang-Ho,Kim, Chi-Kyung The Korean Society for Biotechnology and Bioengine 2000 Biotechnology and Bioprocess Engineering Vol.5 No.6

Pseudomonas sp. strain DJ-12 is a bacterial isolate capable of degrading 4-chlorobiphenyl (4CBP) as a carbon and energy source. The catabolic degradation of 4CBP by the strain DJ-12 was studied along with the genetic organization of the genes responsible for the crucial steps of the catabolic degradation. The catabolic pathway was characterized as being conducted by consecutive reactions of the meta-cleavage of 4CBP, hydrolytic dechlorination of 4-chlorobenzoate (4CBA), hydroxylation of 4-hydroxybenzoate, and meta-cleavage of protocatechuate. The pcbC gene responsible for the meta-cleavage of 4CBP only showed a 30 to 40% homology in its deduced amino acid sequence compared to those of the corresponding genes from other strains. The amino acid sequence of 4CBA-CoA dechlorinase showed an 86% homology with that of Pseudomonas sp. CBS3, yet only a 50% homology with that of Arthrobacter spp. However, the fcb genes for the hydrolytic dechlorination of 4CBA in Pseudomonas sp. DJ-12 showed an uniquely different organization from those of CBS3 and other reported strains. Accordingly, these results indicate that strain DJ-12 can degrade 4CBA completely via meta-cleavage and hydrolytic dechlorination using enzymes that are uniquely different in their amino acid sequences from those of other bacterial strains with the same degradation activities.

Diversity of Bacteriophages Infecting Xanthomonas oryzae pv. oryzae in Paddy Fields and Its Potential to Control Bacterial Leaf Blight of Rice

( Jong Chan Chae ),( Nguyen Bao Hung ),( Sang Mi Yu ),( Ha Kyung Lee ),( Yong Hoon Lee ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.6

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

Hydrolytic Dechlorination of 4-Chlorobenzoate Specified by fcbABC of Pseudomonas sp. DJ-12

CHAE, JONG-CHAN,AHN, KYUNG-JOON,KIM, CHI-CYUNG 한국미생물 · 생명공학회 1998 Journal of microbiology and biotechnology Vol.8 No.6

Cloning of the Gene Responsible for Dechlorination of 4-Chlorobenzoate from Pseudomonas sp. DJ-12 [ Jour. Microbiol. March : 34-39 ]

Jong-chan Chae 충북대학교 약품자원개발연구소 1995 약학논문집 Vol.10 No.-