Authors

Abstract

Plasmid DNA extraction is a fundamental technique in molecular biology and biomedicine. While traditional methods based on Luria–Bertani (LB) medium are sufficient for routine laboratory applications, many advanced downstream uses—such as transfection, gene therapy, and DNA vaccination—require large quantities of plasmid DNA with high purity and structural integrity. In this study, we systematically evaluated Terrific Broth (TB) as an alternative culture medium to enhance plasmid yield and quality in Escherichia coli. Cultures grown in TB achieved significantly higher cell densities and produced markedly increased plasmid yields compared with LB-grown cultures. Agarose gel electrophoresis confirmed that plasmid DNA extracted from TB cultures was predominantly in the supercoiled form with minimal degradation. Furthermore, several practical protocol modifications— including direct inoculation from frozen stocks, controlled freezing–thawing of bacterial pellets, and optimized elution strategies—reduced processing time and overall cost while improving yield. Collectively, these results demonstrate that TB medium is a robust and efficient platform for producing high-quality plasmid DNA suitable for demanding molecular and biomedical applications.

Keywords

Plasmid Extraction, Escherichia coli, Terrific Broth; DNA yield; supercoiled plasmid.