Jump to main content
Jump to site search

Issue 13, 2014
Previous Article Next Article

CotA laccase: high-throughput manipulation and analysis of recombinant enzyme libraries expressed in E. coli using droplet-based microfluidics

Author affiliations

Abstract

We present a high-throughput droplet-based microfluidic analysis/screening platform for directed evolution of CotA laccase: droplet-based microfluidic modules were combined to develop an efficient system that allows cell detection and sorting based on the enzymatic activity. This platform was run on two different operating modes: the “analysis” mode allowing the analysis of the enzymatic activity in droplets at very high rates (>1000 Hz) and the “screening” mode allowing sorting of active droplets at 400 Hz. The screening mode was validated for the directed evolution of the cytoplasmic CotA laccase from B. subtilis, a potential interesting thermophilic cathodic catalyst for biofuel cells. Single E. coli cells expressing either the active CotA laccase (E. coli CotA) or an inactive frameshifted variant (E. coli ΔCotA) were compartmentalized in aqueous droplets containing expression medium. After cell growth and protein expression within the droplets, a fluorogenic substrate was “picoinjected” in each droplet. Fluorescence-activated droplet sorting was then used to sort the droplets containing the desired activity and the corresponding cells were then recultivated and identified using colorimetric assays. We demonstrated that E. coli CotA cells were enriched 191-fold from a 1 : 9 initial ratio of E. coli CotA to E. coli ΔCotA cells (or 437-fold from a 1 : 99 initial ratio) using a sorting rate of 400 droplets per s. This system allows screening of 106 cells in only 4 h, compared to 11 days for screening using microtitre plate-based systems. Besides this low error rate sorting mode, the system can also be used at higher throughputs in “enrichment” screening mode to make an initial purification of a library before further steps of selection. Analysis mode, without sorting, was used to rapidly quantify the activity of a CotA library constructed using error-prone PCR. This mode allows analysis of 106 cells in only 1.5 h.

Graphical abstract: CotA laccase: high-throughput manipulation and analysis of recombinant enzyme libraries expressed in E. coli using droplet-based microfluidics

Back to tab navigation

Supplementary files

Publication details

The article was received on 30 Jan 2014, accepted on 11 Mar 2014 and first published on 11 Mar 2014


Article type: Paper
DOI: 10.1039/C4AN00228H
Citation: Analyst, 2014,139, 3314-3323
  • Open access: Creative Commons BY-NC license
  •   Request permissions

    CotA laccase: high-throughput manipulation and analysis of recombinant enzyme libraries expressed in E. coli using droplet-based microfluidics

    T. Beneyton, F. Coldren, J. Baret, A. D. Griffiths and V. Taly, Analyst, 2014, 139, 3314
    DOI: 10.1039/C4AN00228H

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements