Eliminating effects of particle adsorption to the air/water interface in single-particle cryo-electron microscopy: Bacterial RNA polymerase and CHAPSO

•Cryo-EM of bacterial transcription complexes is hampered by particle orientation bias.•Adsorption to air/water interfaces causes particle orientation.•CHAPSO at its CMC eliminates air/water interface adsorption and orientation bias.•CHAPSO aids cryo-EM structure determination of bacterial transcription complexes.