title: Single-cell screening of photosynthetic growth and lactate production by cyanobacteria.
abstract: 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.
authors.affiliation: Science for Life Laboratory, Division of Proteomics and Nanobiotechnology, KTH Royal Institute of Technology, Stockholm, Sweden ; Novo Nordisk Foundation Center for Biosustainability, KTH Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Petter
authors.initials: P
authors.lastname: Hammar
authors.affiliation: Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands ; Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria.
authors.forename: S Andreas
authors.initials: SA
authors.lastname: Angermayr
authors.affiliation: Science for Life Laboratory, Division of Proteomics and Nanobiotechnology, KTH Royal Institute of Technology, Stockholm, Sweden ; Novo Nordisk Foundation Center for Biosustainability, KTH Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Staffan L
authors.initials: SL
authors.lastname: Sjostrom
authors.affiliation: Science for Life Laboratory, Division of Proteomics and Nanobiotechnology, KTH Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Josefin
authors.initials: J
authors.lastname: van der Meer
authors.affiliation: Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: Hellingwerf
authors.affiliation: Science for Life Laboratory, Division of Proteomics and Nanobiotechnology, KTH Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Elton P
authors.initials: EP
authors.lastname: Hudson
authors.affiliation: Science for Life Laboratory, Division of Proteomics and Nanobiotechnology, KTH Royal Institute of Technology, Stockholm, Sweden ; Novo Nordisk Foundation Center for Biosustainability, KTH Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Haakan N
authors.initials: HN
authors.lastname: Joensson
keywords: Cyanobacteria; Droplet microfluidics; High-throughput screening; Lactate dehydrogenase; Single cell