Methods of isolating clinical-grade plasmid DNA from manufacturing processes, including large-scale fermentation regimes, are disclosed which encompass alternatives to two core unit operations common to plasmid DNA purification processes. The novel upstream and downstream purification processes disclosed herein provide for reduced production costs and increase process robustness. Either or both of the purification processes disclosed herein may be used in combination with additional purification steps known in the art that are associated with DNA plasmid purification technology.