To further assess the loss of BabA expression, the babA promoter region was sequenced for several isolates using primer IR (Table 1). The −10 core promoter element (TATAAT), the +1 transcriptional start site (A), and the ATG translational start codon are boxed. The poly-A tract upstream of the −10 region and the CT repeat region downstream of the translational start site are underlined. In comparison to USU101 (13 A’s, 8 CT’s) the output strains differ in the number of repeats in either one or both of these regions. The lengths of poly-A tracts range from 13 to 15 and the CT repeat lengths range from 8 to 10. The addition of CT repeats, seen in all of the isolates, occurs within the coding region of babA and results in the pre-mature truncation of the protein.