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Microscale Affairs  ZOOM
16/12/2020
Date: 2020/12/16
Microscale Affairs ZOOM

Hello everyone,

Microscale Affairs is back with another seminar! The next seminar will take place on Wednesday, December 16th at 11 AM on Zoom.



Droplet microfluidics to probe cells, chemical reactions and molecular permeation at high throughput
Petra DITTRICH,
Department Biosystems Science and Engineering, ETH Zurich, Switzerland

followed by a 15 min talk by

Optimized gene expression from bacterial chromosome by high-throughput integration and microfluidic screening
Tatyana SALESKI
Laboratory of Biochemistry, CBI, ESPCI Paris, France


ZOOM Link: https://espci.zoom.us/j/93652053743?pwd=RDZYWTJoemppTFpuVS9Ra1laWm5wUT09
Meeting ID: 936 5205 3743
Passcode: 573240

You can find the article and the abstract down below:
Droplet microfluidics to probe cells, chemical reactions and molecular permeation at high throughput:
Droplet microfluidics has emerged as a valuable tool for high-throughput screening of single cells and reactions. Small water droplets of defined and reproducible volumes in the range of pL and nL, immersed in a hydrophobic fluid (an oil), are created at high rates up to kHz and serve as reaction container for further analysis. Droplet microfluidics is easily adaptable to fluorescence microscopes. In consequence, however, the choice of assays is limited as an optical/fluorogenic readout is required. In recent years, we developed a versatile droplet-based microfluidic platform, where thousands of droplets are deposited on a high-density plate for further analysis by time-lapse fluorescence microscopy and matrix-assisted laser desorption/ionization-mass spectrometry allowing for multimodal analysis of reactions and cells including secreted compounds. In addition, the method was modified to investigate permeation across lipid membranes and droplet networks. Here, droplets with a lipid monolayer at the water-oil interphase are deposited close to each other, which immediately form a droplet interface bilayer at the contact area. Diffusion of compounds can be monitored to determine their permeability coefficients, again by fluorescence microscopy in case the molecular species is fluorescent, or by mass spectrometry.
Despite the obvious potential of droplet microfluidics, standard laboratory procedures such as fluid exchange or separation steps are still difficult to transfer. A solution is in-droplet electrophoresis, which is achieved by guiding droplets through an electric field generated by a parallel set of electrodes. In this lecture, this continuous separation method will be introduced and selected applications will be demonstrated.

Optimized gene expression from bacterial chromosome by high-throughput integration and microfluidic screening:
Microbial biosynthesis is a sustainable, high-specificity approach to achieving chemical conversions with the potential to produce a vast assortment of pharmaceutical, fuel, and commodity chemicals. At present, strain development campaigns generally rely on iterative rounds of library construction and testing and production phenotype evaluation is frequently a bottleneck. We have developed a high-throughput screening method, Syntrophic Co-culture Amplification of Production phenotype (SnoCAP), that utilizes a metabolic cross-feeding circuit to convert the production level of inconspicuous target molecules is into highly distinguishable growth phenotypes. When implemented in a droplet-based microfluidics format, this assay enables screening of up to 107 variants per experiment. We then developed a new approach for tuning pathway gene expression levels via integrations into random chromosomal positions followed by SnoCAP screening to identify those with optimal production levels. I will present our work demonstrating multiplexed pathway gene integration and optimization of expression levels for isobutanol production in Escherichia coli.



Looking forward to seeing you,

Reza, for the MsA team


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