In 7002, pstSCAB is separated into two loci: the pstSCA operon and a separate pstB gene. We reintroduced a copy of pstB (sourced from Synechococcus elongatus UTEX 2973 to prevent recombination) as well as a high expression level optimized lac promoter cLac143, generating strain PST+ (Figure ). There is no native pit homolog in 7002, so we integrated a codon optimized E. coli pitA under cLac143 control into a previously characterized neutral site downstream of glpK, generating strain PIT+ (Figure ). Both mutants are maintained under gentamycin selection, and for accurate comparisons we constructed a control strain with gentamycin resistance marker integrated into the glpK neutral site (wild-type).