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Characterization of gltA::luxCDABE Fusion in Escherichia coli as a Toxicity Biosensor
구만복,안주명,Byoung Chan Kim 한국생물공학회 2006 Biotechnology and Bioprocess Engineering Vol.11 No.6
The use of gltA gene, as a new biomarker for environmental stress biomonitoring, was investigated because of its key position as the first enzyme of the tricarboxylic acid (TCA) cycle. A recombinant bioluminescent Escherichia coli strain, EBJM2, was constructed using a plasmid carrying the citrate synthase (gltA) promoter transcribing the Photorhabdus luminescens luxCDABE genes (gltA::luxCDABE). The responses from this strain were studied with five different classes of toxicants: DNA damage chemicals, phenolics, oxidative-stress chemicals, PAHs, and organic solvents. EBJM2 responded strongly to DNA damage chemicals, such as mitomycin C (MMC) and methyl-nitro-nitrosoguanidine (MNNG) and nalidixic acid with the strongest responses. In contrast, tests with several compounds from the other four classes of toxicants gave no significant response. Therefore, EBJM2 was found to be sensitive to DNA damage chemicals.
Response of Bioluminescent Bacteria to Sixteen Azo Dyes
구만복,Hwa Young Lee,Sue Hyung Choi 한국생물공학회 2003 Biotechnology and Bioprocess Engineering Vol.8 No.2
Recombinant bioluminescent bacteria were used to monitor and classify the toxicity of azo dyes. Two constitutive bioluminescent bacteria, Photobacterium phosphoreum and Escherichia coli, E. coli GC2 (lac::luxCDABE), were used to detect the cellular toxicity of the azo dyes. In addition, four stress-inducible bioluminescent E. coli; DPD2794 (recA::luxCDABE), a DNA damage sensitive strain; DPD2540 (fabA::luxCDABE), a membrane damage sensitive strain; DPD2511 (katG::luxCDABE), an oxidative damage sensitive strain; and TV1061 (grpE::luxCDABE), a protein damage sensitive strain, were used to provide information about the type of toxicity caused by crystal violet, the most toxic dye of the 16 azo dyes tested. These results suggest that azo dyes result in serious cellular toxicity in bacteria, and that toxicity monitoring and classification of some azo dyes, in the field, may be possible using these recombinant bioluminescent bacteria.
Specific Detection of DNA Using Quantum Dots and Magnetic Beads for Large Volume Samples
구만복,김연석,Byoung Chan Kim,Jin Hyung Lee,Jungbae Kim 한국생물공학회 2006 Biotechnology and Bioprocess Engineering Vol.11 No.5
Here we present a sensitive DNA detection protocol using quantum dots (QDs) and magnetic beads (MBs) for large volume samples. In this study, QDs, conjugated with streptavidin, were used to produce fluorescent signals while magnetic beads (MBs) were used to isolate and concentrate the signals. The presence of target DNAs leads to the sandwich hybridization between the functionalized QDs, the target DNAs and the MBs. In fact, the QDs-MBs complex, which is bound using the target DNA, can be isolated and then concentrated. The binding of the QDs to the surface of the MBs was confirmed by confocal microscopy and Cd elemental analysis. It was found that the fluorescent intensity was proportional to concentration of the target DNA, while the presence of non-complementary DNA produced no significant fluorescent signal. In addition, the presence of low copies of target DNAs such as 0.5 pM in large volume samples up to 40 mL was successfully detected by using a magnet-assisted concentration protocol which consequently results in the enhancement of the sensitivity more than 100-fold.
지상인자(地上因子)에 의한 순간단위도(瞬間單位圖) 유도(誘導)와 유출량(流出量) 예측(豫測)
천만복 ( Chun Man Bog ),서승덕 ( Suh Seung Duk ) 한국농공학회 1990 韓國農工學會誌 : 전원과 자원 Vol.32 No.3
The purpose of this study is to estimate the flood discharge and runoff volume at a stream by using geomorphologic parameters obtained from the topographic maps following the law of stream classification and ordering by Horton and Strahier. The present model is modified from Cheng's model which derives the geomorphologic instantaneous unit hydrograph. The present model uses the results of Laplace transformation and convolution intergral of probability density function of the travel time at each state. The stream flow velocity parameters are determined as a function of the rainfall intensity, and the effective rainfall is calculated by the SCS method. The total direct runoff volume until the time to peak is estimated by assuming a triangular hydrograph. The model is used to estimate the time to peak, the flood discharge, and the direct runoff at Andong, Imha. Geomchon, and Sunsan basin in the Nakdong River system. The results of the model application are as follows : 1. For each basin, as the rainfall intensity doubles form 1 mm/h to 2 mm/h with the same rainfall duration of 1 hour, the hydrographs show that the runoff volume doubles while the duration of the base flow and the time to peak are the same. This aggrees with the theory of the unit hydrograph. 2. Comparisions of the model predicted and observed values show that small relative errors of 0.44-7.4% of the flood discharge, and 1 hour difference in time to peak except the Geomchon basin which shows 10.32% and 2 hours respectively. 3. When the rainfall intensity is small, the error of flood discharge estimated by using this model is relatively large. The reason of this might be because of introducing the flood velocity concept in the stream flow velocity. 4. Total direct runoff volume until the time to peak estimated by using this model has small relative error comparing with the observed data. 5. The sensitivity analysis of velocity parameters to flood discharge shows that the flood discharge is sensitive to the velocity coefficient while it is insensitive to the ratio of arrival time of moving portion to that of storage portion of a stream and to the ratio of arrival time of stream to that of overland flow.