The tailoring enzymes are required for althiomycin production.

<p><b>A</b>. Assay to assess antimicrobial activity of <i>S. marcescens</i> Db10 and the <i>alb4–5</i> mutant strain (SAN5) against <i>B. subtilis</i> 3610. <b>B.</b> Visualisation of proteins corresponding to the predicted size of Alb4 and Alb5. Total cellular protein from Db10 (wild type <i>S. marcescens</i> Db10), Δ<i>alb3</i> (SAN4) or Δ<i>alb4</i>–<i>5</i> (SAN5) mutants was isolated from cultures grown to stationary phase and separated by SDS-PAGE, followed by staining with Coomassie blue. <b>C–E.</b> Activity assays were performed using <i>Bacillus subtilis</i> NRS1473 as the indicator lawn. The producer strains used are indicated above as: Db10+VC (<i>S. marcescens</i> Db10 pSUPROM); Db10+<i>alb2</i> (<i>S. marcescens</i> Db10 pSAN2); Δ<i>alb2</i>+VC (SAN3 pSUPROM); Δ<i>alb2</i>+<i>alb2</i> (SAN3 pSAN2); Db10+<i>alb3</i> (<i>S. marcescens</i> Db10 pSAN3);Δ<i>alb3_51–262</i>+VC (SAN88 pSUPROM); Δ<i>alb3_51–262</i>+<i>alb3</i> (SAN88 pSAN3); Db10+<i>alb6</i> (<i>S. marcescens</i> Db10 pSAN38); Δ<i>alb6</i>+VC (SAN60 pSUPROM); Δ<i>alb6</i>+<i>alb6</i> (SAN60 pSAN38). ‘VC’ represents the empty vector control.