The article describes a rapid and efficient method for the detection and isolation of plasmids ranging from 2.6 to 350 megadaltons in various bacterial species, including *Agrobacterium*, *Rhizobium*, *Escherichia*, *Salmonella*, *Erwinia*, *Pseudomonas*, and *Xanthomonas*. The method involves using alkaline sodium dodecyl sulfate (pH 12.6) at elevated temperatures to denature chromosomal DNA while preserving plasmid DNA. Proteins and cell debris are removed by phenol-chloroform extraction, and the clarified extract is used for electrophoretic analysis. This procedure allows for the selective isolation of plasmid DNA suitable for further experiments such as nick translation, restriction endonuclease analysis, transformation, and DNA cloning. The method is applicable to both small broth cultures and single bacterial colonies, and it significantly reduces the time required for plasmid isolation compared to traditional methods. The authors also discuss the importance of heat treatment and phenol-chloroform extraction in eliminating chromosomal DNA and ensuring the purity of the plasmid DNA. The protocol has been successfully applied to various bacteria, including those with large plasmids, and has been shown to be effective for both screening and preparative isolation of plasmid DNA.The article describes a rapid and efficient method for the detection and isolation of plasmids ranging from 2.6 to 350 megadaltons in various bacterial species, including *Agrobacterium*, *Rhizobium*, *Escherichia*, *Salmonella*, *Erwinia*, *Pseudomonas*, and *Xanthomonas*. The method involves using alkaline sodium dodecyl sulfate (pH 12.6) at elevated temperatures to denature chromosomal DNA while preserving plasmid DNA. Proteins and cell debris are removed by phenol-chloroform extraction, and the clarified extract is used for electrophoretic analysis. This procedure allows for the selective isolation of plasmid DNA suitable for further experiments such as nick translation, restriction endonuclease analysis, transformation, and DNA cloning. The method is applicable to both small broth cultures and single bacterial colonies, and it significantly reduces the time required for plasmid isolation compared to traditional methods. The authors also discuss the importance of heat treatment and phenol-chloroform extraction in eliminating chromosomal DNA and ensuring the purity of the plasmid DNA. The protocol has been successfully applied to various bacteria, including those with large plasmids, and has been shown to be effective for both screening and preparative isolation of plasmid DNA.