Single-cell screening of photosynthetic growth and lactate production by cyanobacteria

Petter Hammar, S. Andreas Angermayr, Staffan L. Sjostrom, Josefin van der Meer, Klaas J. Hellingwerf, Elton P. Hudson, Håkan Jönsson

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Background: Photosynthetic cyanobacteria are attractive for a range of biotechnological applications including biofuel production. However, due to slow growth, screening of mutant libraries using microtiter plates is not feasible.Results: We present a method for high-throughput, single-cell analysis and sorting of genetically engineered l-lactate-producing strains of Synechocystis sp. PCC6803. A microfluidic device is used to encapsulate single cells in picoliter droplets, assay the droplets for L-lactate production, and sort strains with high productivity. We demonstrate the separation of low- and high-producing reference strains, as well as enrichment of a more productive L-lactate-synthesizing population after UV-induced mutagenesis. The droplet platform also revealed population heterogeneity in photosynthetic growth and lactate production, as well as the presence of metabolically stalled cells.Conclusions: The workflow will facilitate metabolic engineering and directed evolution studies and will be useful in studies of cyanobacteria biochemistry and physiology.
Original languageEnglish
JournalBiotechnology for Biofuels
Issue number1
Number of pages8
Publication statusPublished - 2015

Bibliographical note

© 2015 Hammar et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.


  • Cyanobacteria
  • Single cell
  • Droplet microfluidics
  • High-throughput screening
  • Lactate dehydrogenase

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