Export of extracellular polysaccharides modulates adherence of the Cyanobacterium synechocystis

PLoS One. 2013 Sep 10;8(9):e74514. doi: 10.1371/journal.pone.0074514. eCollection 2013.


The field of cyanobacterial biofuel production is advancing rapidly, yet we know little of the basic biology of these organisms outside of their photosynthetic pathways. We aimed to gain a greater understanding of how the cyanobacterium Synechocystis PCC 6803 (Synechocystis, hereafter) modulates its cell surface. Such understanding will allow for the creation of mutants that autoflocculate in a regulated way, thus avoiding energy intensive centrifugation in the creation of biofuels. We constructed mutant strains lacking genes predicted to function in carbohydrate transport or synthesis. Strains with gene deletions of slr0977 (predicted to encode a permease component of an ABC transporter), slr0982 (predicted to encode an ATP binding component of an ABC transporter) and slr1610 (predicted to encode a methyltransferase) demonstrated flocculent phenotypes and increased adherence to glass. Upon bioinformatic inspection, the gene products of slr0977, slr0982, and slr1610 appear to function in O-antigen (OAg) transport and synthesis. However, the analysis provided here demonstrated no differences between OAg purified from wild-type and mutants. However, exopolysaccharides (EPS) purified from mutants were altered in composition when compared to wild-type. Our data suggest that there are multiple means to modulate the cell surface of Synechocystis by disrupting different combinations of ABC transporters and/or glycosyl transferases. Further understanding of these mechanisms may allow for the development of industrially and ecologically useful strains of cyanobacteria. Additionally, these data imply that many cyanobacterial gene products may possess as-yet undiscovered functions, and are meritorious of further study.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / deficiency
  • ATP-Binding Cassette Transporters / genetics
  • Bacterial Adhesion
  • Biofuels
  • Biological Transport
  • Gene Expression Regulation, Bacterial*
  • Genes, Bacterial*
  • Glass
  • Industrial Microbiology*
  • Metabolic Engineering*
  • Methyltransferases / deficiency
  • Methyltransferases / genetics
  • Multigene Family
  • O Antigens / genetics*
  • O Antigens / metabolism
  • Synechocystis / genetics*
  • Synechocystis / metabolism


  • ATP-Binding Cassette Transporters
  • Biofuels
  • O Antigens
  • Methyltransferases

Grant support

MLF, RA, and YL were supported by US Department of Energy Advanced Research Projects Agency–Energy Grant (DE-AR00000011). MLF and RA recieved additional funding from ASU Lightworks, (http://asulightworks.com/). Carbohydrate analysis was funded in part by the Department of Energy grant number DE-FG02-93ER-20097. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.