ABSTRACTIn our previous study,Bacillus subtilisstrain BSK3S, containing a polymyxin biosynthetic gene cluster fromPaenibacillus polymyxa, could produce polymyxin only in the presence of exogenously addedl-2,4-diaminobutyric acid (Dab). The dependence of polymyxin production on exogenous Dab was removed by introducing anectBgene encoding the diaminobutyrate synthase ofP. polymyxainto BSK3S (resulting in strain BSK4). We found, by observing the complete inhibition of polymyxin synthesis when thespo0Agene was knocked out (strain BSK4-0A), that Spo0A is indispensable for the production of polymyxin. Interestingly, theabrB-spo0Adouble-knockout mutant, BSK4-0A-rB, and the singleabrBmutant, BSK4-rB, showed 1.7- and 2.3-fold increases, respectively, in polymyxin production over that of BSK4. These results coincided with the transcription levels ofpmxAin the strains observed by quantitative real-time PCR (qRT-PCR). The AbrB protein was shown to bind directly to the upstream region ofpmxA, indicating that AbrB directly inhibits the transcription of polymyxin biosynthetic genes. The BSK4-rB strain, producing high levels of polymyxin, will be useful for the development and production of novel polymyxin derivatives.
Highly efficient production of Clostridium cellulolyticum H10 d-psicose 3-epimerase in Bacillus subtilis and use of these cells to produce d-psicose
