“…During the course of expressing the disorazol gene cluster, B. thailandensis E264 showed better performance than the wellstudied host DSM 7029 (Bian et al, 2017;Yan et al, 2018;Liu J. et al, 2021) in terms of growth rate and production. To facilitate genetic manipulation, three efflux pumps in strain E264, AmrAB-OprA (abbreviated as A), BpeAB-OprB (B), and BpeEF-OprC (C) (Biot et al, 2011(Biot et al, , 2013, were inactivated by homologous recombination combined with pheS counterselection mediated seamless gene deletions (Barrett et al, 2008), and mutants with one, two, or three pump knockouts were obtained.…”