Participates in both the initiation and recycling phases of transcription. In the presence of the delta subunit, RNAP displays an increased specificity of transcription, a decreased affinity for nucleic acids, and an increased efficiency of RNA synthesis because of enhanced recycling. May function in sigma factor switching. It displaces RNA bound to RNA polymerase in a binary complex. RNAP is composed of a core of 2 alpha, a beta and a beta' subunit. The core is associated with a delta subunit, and at least one of epsilon or omega (PubMed:6802805, PubMed:18289874, PubMed:21710567). When a sigma factor is associated with the core the holoenzyme is formed, which can initiate transcription (PubMed:18289874). No visible phenotype; grows as well as wild-type at 25-49 degrees Celsius, no apparent impairment in sporulation or phage SP01 growth. Belongs to the RpoE family.