Heparin-mediated transformation of Escherichia coli with Ustilago maydis DNA

The inhibiton of Escherichia coli transformation caused by simple preparations of Ustilago maydis plasmid and genomic DNA can be efficiently overcome by the use of the linear polyanion heparin. Techniques using heparin have been derived that should facilitate the production and isolation of plasmids passed through Ustilago maydis and may be of benefit in other systems where similar inhibitory phenomena or low transformability are observed.