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A Genetically Encoded Biosensor for the Detection of Levulinic Acid
Kim Tae Hyun,Woo Seung-Gyun,Kim Seong Keun,Yoo Byeong Hyeon,Shin Jonghyeok,Rha Eugene,Kim Soo Jung,Kwon Kil Koang,Lee Hyewon,Kim Haseong,Kim Hee-Taek,Sung Bong-Hyun,Lee Seung-Goo,Lee Dae-Hee 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.4
Levulinic acid (LA) is a valuable chemical used in fuel additives, fragrances, and polymers. In this study, we proposed possible biosynthetic pathways for LA production from lignin and poly(ethylene terephthalate). We also created a genetically encoded biosensor responsive to LA, which can be used for screening and evolving the LA biosynthesis pathway genes, by employing an LvaR transcriptional regulator of Pseudomonas putida KT2440 to express a fluorescent reporter gene. The LvaR regulator senses LA as a cognate ligand. The LA biosensor was first examined in an Escherichia coli strain and was found to be non-functional. When the host of the LA biosensor was switched from E. coli to P. putida KT2440, the LA biosensor showed a linear correlation between fluorescence intensity and LA concentration in the range of 0.156–10 mM LA. In addition, we determined that 0.156 mM LA was the limit of LA detection in P. putida KT2440 harboring an LA-responsive biosensor. The maximal fluorescence increase was 12.3-fold in the presence of 10 mM LA compared to that in the absence of LA. The individual cell responses to LA concentrations reflected the population-averaged responses, which enabled high-throughput screening of enzymes and metabolic pathways involved in LA biosynthesis and sustainable production of LA in engineered microbes.
권길광(Kil Koang Kwon),윤석민(Seok Min Yoon),최창호(Chang Ho Choi),정봉근(Bong Geun Jeong),이기원(Ki Won Lee),이동희(Dong Heui Yi),김형주(Hyung Joo Kim) 大韓環境工學會 2007 대한환경공학회지 Vol.29 No.6
본 연구에서는 개인용 컴퓨터(PC) 내부의 시료를 채취하여, 세균의 CFU와 곰팡이의 종류를 분석하였다. 시료는 대중 PC 이용시설(PC방), 대학실험실 및 대학 전산실습실의 PC 51대에서 채취하였다. CFU(colony forming unit)법을 이용한 세균수의 경우, 컴퓨터 총 작동시간이 증가할수록 PC 내부의 세균수는 증가하는 것으로 확인되었으며(r2 = 0.90), PC 내부 부품 중에서는 CPU 냉각 팬에서 가장 높은 수치로 확인되었다(평균 605 CFU/cm2). 곰팡이의 경우, 다수의 유해성을 지닌 곰팡이가 검출되었으며, 그 중 Aspergillus sp.와 Penicillium sp.가 가장 많은 비율로 존재함이 확인되었다. 또한 PC 내부에서 채취된 먼지에서는 mg 당 212 CFU의 세균이 발견되었다. 본 연구의 결과, PC 내부에는 여러 다양한 종류의 미생물이 존재한다는 것을 확인하였으며, 이 결과는 PC의 취급, 사용 및 정비 시 각종 미생물에 의한 감염의 가능성이 있다는 것을 나타내고 있다. Presence and distribution of bacteria and fungi in inner compartment of PCs(Personal Computers) were investigated. Samples for the analysis were collected from inside of PCs which had been used in various facilities including public computer facilities, laboratories and computer training rooms of a university. Total number of PC examined in this study was 51 each. When the total CFU(colony forming unit) of the inner compartment of the PCs was measured, the bacterial count was found to be dependent on the operation time(total running time) of PCs. When the distribution of bacteria in the inner compartment of PCs was estimated, CPU(Central Processing Unit) cooling fan area showed the highest bacterial concentration(average 605 CFU/cm2). In the case of the fungi, various opportunistic pathogens including Aspergillus sp. and Penicillium sp. were isolated and identified in the inner compartment of PCs. And the average of bacterial number in the dust collected from the PCs was 212 CFU/mg. These results indicated that handling of PC might have a risk of infection by the microorganism.
HIGH DENSITY LIPOPROTEIN SUBFRACTION IN DIABETES MELLITUS
Choi, Young Kil,Kim, Koang Won,Kim, Young Seoul 대한당뇨병학회 1981 Diabetes and Metabolism Journal Vol.6 No.1
Background: Peripheral insulin resistance, increased hepatic glucose production, and impatred insulin secre- tion are the three charaeteristic f.eatures that under1ying the deranged carbohydrate metabolism in type II diabetes. Islet amyloid palypeptide (IAPP, amylin) is a 37-aminoacid peptide that was isolated from pancreatic islet amyloid of type II diabetic and insulinoma patients. Recent interest has focused on the potenital role of amylin in the pathogenesis of type II diibetes. Method: We determined amylin and C-peptide response in plasma to oral glucose administration in 5 patients with type I diabetes (group 1), 8 patients with type II diabetes (Group 2), and 9 normal controls (Group 3), by specific amylin radioimmunoassay methods. In group I, II, III, ages (mean+SD) were 18+-6 years, 43+-14 years, 39+-15 years espectively. BMI (mean+SD) were 16.8+-2.1, 21.5+-2.3, 21.2+-3.8 respectively. Result: 1) Plasma C-peptide levels after oral administration of 75 g glucose wre significantly (p$lt;0.05) higher in patients with type II diabetes and normaI control groups than in patients with type I diabetes. 2) Plasma amylin conc0ntrations after oral adminis- tration of 75 g glucose showed no significant difference between in patients with type II diabetes and in normal control groups. But plasma amylin conentrations in patients with type lI diabetes and in normal control groupe were significant.ly (p$lt;0.05) higher than in patiente with type I diabet.es. 3) There were signifieant (p$lt; 0.01) correlations (r' =0. 47) between plasma amyliin and C-peptide concentration. Conclusion: These reaults suggest that amylin is cosecreted with insulin and C-peptide in response to a glucose load. But there are no differences in plasma amylin concentrations between type II diabetic and normal control subjects. Therefore, further studies will be required to determine whether amylin is a physiologi- cal regulator of carbohydrate metabolism in human.