Plasmid maps of the non-conditional control plasmid pMTL83251-lacI-T (A) and conditional plasmid pMTL83251-lacI (B). Key: CD0164 terminator, a transcriptional terminator isolated from downstream of the Clostridium difficile strain 630 CD0164 gene; lacI, the E. coli gene encoding LacI repressor; Pptb, the promoter of the C. beijerinckii gene encoding phosphotransbutyrylase; Pfac, the promoter of the C. pasteurianum ferredoxin gene derivatised to include an E. coli lac operator; repH, replication region of the Clostridium butyricum plasmid pCB102; ermB, the macrolide-lincosamide-streptogramin B antibiotic resistance gene of plasmid pAMß1; ColE1, the replication origin of plasmid ColE1, and; traJ, transfer function of the RP4 oriT region. Cpa fdx terminator, transcriptional terminator of the ferredoxin gene of C. pasteurianum (this feature is underlined due to its existence only in A: pMTL83251-lacI-T, but not in B: pMTL83251-lacI). C and D: the ability to replicate of pMTL83251-lacI-T and pMTL83251-lacI in of C. acetobutylicum (C) and C. sporogenes (D) in the absence (CFU account in black) and presence (CFU account in grey) of IPTG.