Provided herein are processes for producing an improved culture of cells comprising an engineered butanol biosynthetic pathway. The processes comprise (a) providing a cell culture of recombinant microorganisms comprising an engineered butanol biosynthetic pathway, wherein the engineered butanol biosynthetic pathway is minimal or not activated; and (b) growing the culture of recombinant microorganisms under adaptive conditions whereby pathway activation is increased to produce an improved cell culture and whereby the improved cell culture is capable of continuing to grow in fermentation.