The invention provides DNA, heterologous host cells capable of transcribing, translating or expressing said DNA and methods employing such host cells and cultures thereof for an improved in vivo production of acylated cephalosporins with higher yield. According to the invention, a host cell is provided comprising an enzyme having expandase activity which is predominantly localized in the cytosol (as opposed to localized mainly in or with the peroxisomes or microbodies) of the host cell.