Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. This sigma factor is responsible for the expression of sporulation specific genes (PubMed:8759874). Interaction with SpoIIAB inhibits sigma-F activity throughout the cell before the formation of the asymmetric septum; after septation the interaction is confined to the mother cell, and sigma F activity is released in the prespore. Responsible for expression of csfB (the anti-sigma-G factor Gin) (PubMed:8759874). Associates with the RNAP core only in stationary phase cells (PubMed:21710567). Interaction with SpoIIAB inhibits sigma-F activity throughout the cell before the formation of the asymmetric septum; after septation the interaction is confined to the mother cell, and sigma-F activity is released in the prespore (PubMed:8358793). Fin, a second, forespore-specific anti-sigma factor is induced in 2 successive waves by sigma-F and sigma-G, by antagonizing sigma-F it allows the switch to sigma-G factor and progression to the late sporulation development stages (PubMed:21037003). Interacts transiently with the RNAP core. Produced in the predivisional sporangium, but does not become active in directing gene expression until after septum formation when its activity is restricted to the forespore (at protein level). Association with RNAP core increases during sporulation but not tested stresses (at protein level). In spo-63 (loss of residues 27-255); no spores develop, no induction of sporulation-associated enzymes. Belongs to the sigma-70 factor family.