Modifications to Bacterial Growth Conditions and Mini-Prep Procedure for Maximizing DNA Yield

Abstract

Plasmid DNA purification from Escherichia coli (E. coli) bacterial cells is a fundamental protocol in standard molecular biology laboratories, essential for experiments such as transfection, polymerase chain reactions, and restriction enzyme digests. To improve yield, we have modified the growth broth, the miniprep protocol precipitation and elution buffer to optimize DNA yield and purity. We hypothesized that cells under the condition of TB broth, ethanol, and double distilled water will generate the highest DNA yield and purity. Six conditions were used to test for growth differences between Terrific Broth (TB) and Lysogeny Broth (LB). The quality of DNA samples that were isolated using ethanol and HBC buffer, and the elution quality between Tris-EDTA (TE buffer) and double distilled water were analyzed. The DNA concentration and purity were measured, and E. coli cells grown in TB with no mini prep modifications had the highest DNA yield. This suggests that TB should be used in substitution of LB for transformed bacterial amplification when large quantities of plasmid elution are required.