Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. This sigma factor is required for normal cell wall integrity; it is recruited by RNA polymerase to transcribe genes with cell wall-related functions. It is also involved in the transcription of the dagA gene coding for an extracellular agar-degrading enzyme. By CseB, in response to cell envelope stress. Belongs to the sigma-70 factor family. ECF subfamily.