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Man Bock Gu – 1st expert on this subject based on the ideXlab platform
prescreening of natural products in drug discovery using recombinant Bioluminescent BacteriaBiotechnology and Bioprocess Engineering, 2019Co-Authors: Man Bock GuAbstract:
Strains of recombinant Bioluminescent Bacteria (RBB) which respond to toxic environments using various stress promoters are practical means of assessing toxicity. In previous research, RBB has proven useful for highthroughput screening in the drug development process. The goal of this research is to demonstrate that RBB can also be used for the toxicity screening of natural products. The RBB strains used were DPD2511, BBTSbmC, TV1061, and GC2, which were selected to respond to oxidative stress, DNA damage, protein damage, and cellular toxicity, respectively. The test drugs (paclitaxel, etoposide, and pentostatin) were carefully selected because these drugs needed to be natural products or their derivatives whose cellular toxicity had previously been reported from human cell line assays. After treating the RBB strains with various doses of the chosen drugs, their Bioluminescent signals were measured over time. The effectiveness of the RBB method was proven by comparing its results to existing toxicity data for the selected drugs. In addition, a similar test using podophyllotoxin, a precursor of etoposide, and a derivative of podophyllotoxin, teniposide, was conducted to prove that the RBB method is suitable for a comparative analysis of toxicity among chemicals with similar molecular structures. As a detection method, RBB Bacteria provide a much easier and more rapid culturing process compared to conventional human cell line assays. Because the implementation of the RBB method in the drug discovery process would enable efficient prescreening, a significant reduction in time, effort, and development costs are expected.
a dip stick type biosensor using Bioluminescent Bacteria encapsulated in color coded alginate microbeads for detection of water toxicityAnalyst, 2014Co-Authors: Insup Jung, Man Bock GuAbstract:
The use of genetically engineered Bioluminescent Bacteria, in which bioluminescence is induced by different modes of toxic action, represents an alternative to acute toxicity tests using living aquatic organisms (plants, vertebrates, or invertebrates) in an aqueous environment. A number of these Bacterial strains have been developed, but there have been no attempts to develop a hand-held type of biosensor for monitoring or identification of toxicity. We report a facile dip-stick type biosensor using genetically engineered Bioluminescent Bacteria as a new platform for classification and identification of toxicity in water environments. This dip-stick type biosensor is composed of eight different optically color-coded functional alginate beads that each encapsulates a different Bioluminescent Bacterial strain and its corresponding fluorescent microbead. These color-coded microbeads exhibit easy identification of encapsulated microbeads, since each microbead has a different color code depending on the Bioluminescent Bacterial strain contained and improved cell-stability compared to liquid culture. This dip-stick type biosensor can discriminate different modes of toxic actions (i.e. DNA damage, oxidative damage, cell-membrane damage, or protein damage) of sample water tested by simply dipping the stick into the water samples. It was found that each color-coded microbead emitted distinct bioluminescence, and each dip-stick type biosensor showed different bioluminescence patterns within 2 hours, depending on the toxic chemicals contained in LB medium, tap water, or river water samples. This dip-stick type biosensor can, therefore, be widely and practically used in checking toxicity of water in the environment primarily in situ, possibly indicating the status of biodiversity.
Fabrication of a bio-MEMS based cell-chip for toxicity monitoringBiosensors and Bioelectronics, 2007Co-Authors: Sung Keun Yoo, Jin-hyung Lee, Sung-sik Yun, Man Bock Gu, Jong Hyun LeeAbstract:
A bio-MEMS based cell-chip that can detect a specific toxicity was fabricated by patterning and immobilizing Bioluminescent Bacteria in a microfluidic chip. Since the emitted light intensity of Bioluminescent Bacteria changed in response to the presence of chemicals, the Bacteria were used as the toxicity indicator in this study. A pattern of immobilized cells was successfully generated by photolithography, utilizing a water-soluble and negatively photosensitive polymer, PVA-SbQ (polyvinyl alcohol-styrylpyridinium) as an immobilization material. Using the recombinant Escherichia coli (E. coli) strain, GC2, which is sensitive to general toxicity, the following were investigated for the immobilization: an acceptable dose of long-wavelength UV light, the biocompatibility of the polymer, and the effect of the chip-environment. We found that 10 min of UV light exposure, the toxicity of polymer (SPP-H-13-bio), and the other chip-environment did not inhibit cell metabolism significantly for making a micro-cell-chip. Detection of a specific toxicity was demonstrated by simply immobilizing the Bioluminescent Bacteria, DK1, which increased bioluminescence in the presence of oxidative damage in the cells. An injection of hydrogen peroxide of 0.88 mM induced 10-fold increase in Bioluminescent intensity confirming the capability of the chip for toxicity monitoring. © 2006 Elsevier B.V. All rights reserved.
Andre Ex Brown – 2nd expert on this subject based on the ideXlab platform
measuring caenorhabditis elegans spatial foraging and food intake using Bioluminescent BacteriaGenetics, 2020Co-Authors: Siyu Serena Ding, Andre Ex Brown, Maksym Romenskyy, Karen S SarkisyanAbstract:
For most animals, feeding includes two behaviors: foraging to find a food patch and food intake once a patch is found. The nematode Caenorhabditis elegans is a useful model for studying the genetics of both behaviors. However, most methods of measuring feeding in worms quantify either foraging behavior or food intake, but not both. Imaging the depletion of fluorescently labeled Bacteria provides information on both the distribution and amount of consumption, but even after patch exhaustion a prominent background signal remains, which complicates quantification. Here, we used a Bioluminescent Escherichia coli strain to quantify C. elegans feeding. With light emission tightly coupled to active metabolism, only living Bacteria are capable of bioluminescence, so the signal is lost upon ingestion. We quantified the loss of bioluminescence using N2 reference worms and eat-2 mutants, and found a nearly 100-fold increase in signal-to-background ratio and lower background compared to loss of fluorescence. We also quantified feeding using aggregating npr-1 mutant worms. We found that groups of npr-1 mutants first clear Bacteria from within the cluster before foraging collectively for more food; similarly, during large population swarming, only worms at the migrating front are in contact with Bacteria. These results demonstrate the usefulness of Bioluminescent Bacteria for quantifying feeding and generating insights into the spatial pattern of food consumption.
measuring c elegans spatial foraging and food intake using Bioluminescent BacteriabioRxiv, 2019Co-Authors: Siyu Serena Ding, Karen S Sarkisyan, Andre Ex BrownAbstract:
ABSTRACT For most animals, feeding includes two behaviours: foraging to find a food patch and food intake once a patch is found. The nematode Caenorhabditis elegans is a useful model for studying the genetics of both behaviours. However, most methods of measuring feeding in worms quantify either foraging behaviour or food intake but not both. Imaging the depletion of fluorescently labelled Bacteria provides information on both the distribution and amount of consumption, but even after patch exhaustion a prominent background signal remains, which complicates quantification. Here, we used a Bioluminescent Escherichia coli strain to quantify C. elegans feeding. With light emission tightly coupled to active metabolism, only living Bacteria are capable of bioluminescence so the signal is lost upon ingestion. We quantified the loss of bioluminescence using N2 reference worms and eat-2 mutants, and found a nearly 100-fold increase in signal-to-background ratio and lower background compared to loss of fluorescence. We also quantified feeding using aggregating npr-1 mutant worms. We found that groups of npr-1 mutants first clear Bacteria from each other before foraging collectively for more food; similarly, during high density swarming, only worms at the migrating front are in contact with Bacteria. These results demonstrate the usefulness of Bioluminescent Bacteria for quantifying feeding and suggest a hygiene hypothesis for the function of C. elegans aggregation and swarming.
Paul D Frymier – 3rd expert on this subject based on the ideXlab platform
Comparative Study of Two Bioassays for Applications in Influent Wastewater Toxicity MonitoringJournal of Environmental Engineering, 2003Co-Authors: Paul D FrymierAbstract:
Bioluminescent Bacteria-based assays can be used for influent wastewater toxicity monitoring for biological wastewater treatment systems. The most thoroughly studied Bioluminescent Bacteria-based test is the Microtox® assay. However, the response to toxicants of Photobacterium phosphoreum, the marine Bacterial strain used in this assay, is different from that of the activated sludge microorganisms. We developed a continuous influent wastewater monitoring system based on the Bioluminescent bacterium Shk1, a genetically modified Pseudomonad isolated from the activated sludge in an industrial wastewater treatment plant. The Shk1 toxicity data were correlated with the Microtox® toxicity data for 79 organic compounds and the two toxicity assays were compared. The Shk1 assay is less sensitive than the Microtox® assay and could therefore be more suitable for influent wastewater toxicity monitoring.
estimating the toxicities of organic chemicals to Bioluminescent Bacteria and activated sludgeWater Research, 2002Co-Authors: Paul D FrymierAbstract:
Abstract Toxicity assays based on Bioluminescent Bacteria have several advantages including a quick response and an easily measured signal. The Shk1 assay is a procedure for wastewater toxicity testing based on the Bioluminescent bacterium Shk1. Using the Shk1 assay, the toxicity of 98 organic chemicals were measured and EC 50 values were obtained. Quantitative structure–activity relationship (QSAR) models based on the logarithm of the octanol–water partition coefficient (log( K ow )) were developed for individual groups of organic chemicals with different functional groups. The correlation coefficients for different groups of organic compounds varied between 0.69 and 0.99. An overall QSAR model without discriminating the functional groups, which can be used for a quick estimate of the toxicities of organic chemicals, was also developed and model predictions were compared to experimental data. The model accuracy was found to be one order of magnitude from the observed values.