Hofmeister series salts enhance purification of plasmid DNA by non-ionic detergents

Ion‐exchange chromatography is the standard technique used for plasmid DNA purification, an essential molecular biology procedure. Non‐ionic detergents (NIDs) have been used for plasmid DNA purification, but it is unclear whether Hofmeister series salts (HSS) change the solubility and phase separation properties of specific NIDs, enhancing plasmid DNA purification. After scaling‐up NID‐mediated plasmid DNA isolation, we established that NIDs in HSS solutions minimize plasmid DNA contamination with protein. In addition, large‐scale NID/HSS solutions eliminated lipopolysaccharides (LPS) contamination of plasmid DNA more effectively than Qiagen ion‐exchange columns. Large‐scale NID isolation/NID purification generated increased yields of high‐quality DNA compared to alkali isolation/column purification. This work characterizes how HSS enhance NID‐mediated plasmid DNA purification, and demonstrates that NID phase transition is not necessary for LPS removal from plasmid DNA. Specific NIDs such as IGEPAL CA‐520 can be utilized for rapid, inexpensive, and efficient laboratory‐based large‐scale plasmid DNA purification, outperforming Qiagen‐based column procedures. Biotechnol. Bioeng. 2011; 108:1872–1882. © 2011 Wiley Periodicals, Inc.