title: A novel locus for mycelial aggregation forms a gateway to improved Streptomyces cell factories.
abstract: BACKGROUND
  Streptomycetes produce a plethora of natural products including antibiotics and anticancer drugs, as well as many industrial enzymes. Their mycelial life style is a major bottleneck for industrial exploitation and over decades strain improvement programs have selected production strains with better growth properties. Uncovering the nature of the underlying mutations should allow the ready transfer of desirable traits to other production hosts.
  
  
  RESULTS
  Here we report that the mat gene cluster, which was identified through reverse engineering of a non-pelleting mutant selected in a chemostat, is key to pellet formation of Streptomyces lividans. Deletion of matA or matB, which encode putative polysaccharide synthases, effects mycelial metamorphosis, with very small and open mycelia. Growth rate and productivity of the matAB null mutant were increased by over 60% as compared to the wild-type strain.
  
  
  CONCLUSIONS
  Here, we present a way to counteract pellet formation by streptomycetes, which is one of the major bottlenecks in their industrial application. The mat locus is an ideal target for rational strain design approaches aimed at improving streptomycetes as industrial production hosts.
authors.affiliation: Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA, Leiden, The Netherlands. dinovandissel@gmail.com.
authors.forename: Dino
authors.initials: D
authors.lastname: van Dissel
authors.affiliation: Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA, Leiden, The Netherlands. d.claessen@biology.leidenuniv.nl.
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.affiliation: Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Adolf-Reichwein-Str. 23, 07745, Jena, Germany. martin.roth@hki-jena.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Roth
authors.affiliation: Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA, Leiden, The Netherlands. g.wezel@biology.leidenuniv.nl.
authors.forename: Gilles P
authors.initials: GP
authors.lastname: van Wezel
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001431:Bacteriological Techniques / Q000295:instrumentation / Q000379:methods*; D018533:Biomass; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D007218:Industrial Microbiology / Q000295:instrumentation / Q000379:methods; D005810:Multigene Family; D009154:Mutation; D020641:Polymorphism, Single Nucleotide; D015203:Reproducibility of Results; D048170:Streptomyces lividans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005964:Glucosyltransferases; D000581:Amidohydrolases; C022427:polysaccharide deacetylase