title: Highly efficient protoplast transformation system for Streptococcus faecalis and a new Escherichia coli-S. faecalis shuttle vector.
abstract: A highly efficient protoplast transformation system for Streptococcus faecalis has been developed by systematically optimizing different parameters. Up to 10(6) transformants per micrograms of DNA were consistently obtained within 3 days, and cell wall regeneration of protoplasts was virtually 100%. A systematic search for useful vectors showed that the broad-host-range plasmid pIP501 could transform S. faecalis at a high frequency (6.3 X 10(4) transformants per microgram). By combining a high-copy-number derivative of pIP501, designated pGB354, with the Escherichia coli vector pACYC184, we constructed a new E. coli-S. faecalis shuttle vector (pAM401) having nine unique restriction sites. In a shotgun cloning experiment, we ligated a tetracycline resistance determinant from Streptococcus sanguis chromosomal DNA into pAM401 by direct transformation of S. faecalis, establishing the utility of the protoplast transformation system and of the new shuttle vector.
mesh_terms: D003001:Cloning, Molecular; D003470:Culture Media; D004262:DNA Restriction Enzymes; D004352:Drug Resistance, Microbial; D013293:Enterococcus faecalis / Q000235:genetics* / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics*; D005822:Genetic Vectors; D010957:Plasmids; D011092:Polyethylene Glycols; D011523:Protoplasts; D013298:Streptococcus sanguis / Q000187:drug effects / Q000235:genetics; D013752:Tetracycline / Q000494:pharmacology; D014169:Transformation, Bacterial
chemical_list: D003470:Culture Media; D011092:Polyethylene Glycols; D004262:DNA Restriction Enzymes; D013752:Tetracycline