title: Novel methods for genetic transformation of natural Bacillus subtilis isolates used to study the regulation of the mycosubtilin and surfactin synthetases.
abstract: Natural isolates of Bacillus subtilis are often difficult to transform due to their low genetic competence levels. Here we describe two methods that stimulate natural transformation. The first method uses plasmid pGSP12, which expresses the competence transcription factor ComK and stimulates competence development about 100-fold. The second method stimulates Campbell-type recombination of DNA ligation mixtures in B. subtilis by the addition of polyethylene glycol. We employed these novel methods to study the regulation of the synthetases for the lipopeptide antibiotics mycosubtilin (myc) and surfactin (srfA) in B. subtilis strain ATCC 6633. By means of lacZ reporter fusions, it was shown that the expression of srfA is >100 times lower in strain ATCC 6633 than in the laboratory strain B. subtilis 168. Expression of the myc operon was highest in rich medium, whereas srfA expression reached maximal levels in minimal medium. Further genetic analyses showed that the srfA operon is mainly regulated by the response regulator ComA, while the myc operon is primarily regulated by the transition-state regulator AbrB. Although there is in vitro evidence for a synergistic activity of mycosubtilin and surfactin, the expression of both lipopeptide antibiotics is clearly not coordinated.
authors.affiliation: Department of Genetics, University of Groningen, The Netherlands.
authors.forename: Erwin H
authors.initials: EH
authors.lastname: Duitman
authors.forename: Dobek
authors.initials: D
authors.lastname: Wyczawski
authors.forename: Ludolf G
authors.initials: LG
authors.lastname: Boven
authors.forename: Gerard
authors.initials: G
authors.lastname: Venema
authors.forename: Oscar P
authors.initials: OP
authors.lastname: Kuipers
authors.forename: Leendert W
authors.initials: LW
authors.lastname: Hamoen
mesh_terms: D019677:Artificial Gene Fusion; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000235:genetics; D008074:Lipoproteins / Q000096:biosynthesis / Q000235:genetics; D009876:Operon / Q000235:genetics; D010453:Peptide Synthases / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011092:Polyethylene Glycols; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014169:Transformation, Bacterial; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: C060762:AbrB protein, Bacillus subtilis; D001426:Bacterial Proteins; C061262:ComA protein, Bacteria; D004268:DNA-Binding Proteins; D008074:Lipoproteins; D014157:Transcription Factors; C012448:mycosubtiline; C087449:comK protein, Bacillus subtilis; D011092:Polyethylene Glycols; D001616:beta-Galactosidase; D010453:Peptide Synthases; C069542:surfactin synthetase