A rhodococcal indole oxygenase gene (ido) catalyzing the biosynthesis
of indigo pigment was cloned into S. thermophilus ST128. Expression ve
ctors containing an S. thermophilus plasmid replicon (pER8) and promot
ers (sP1 and STP2201) were used as the cloning vehicles. Northern blot
analysis confirmed the transcriptional expression of the ido gene int
o its mRNA in the ST transformants.