[Microbiology] Phe Auxotrophic E. Coli BL21(DE3)

[jflood from chem.utoronto.ca]

Hello, I'm looking for a Phe auxotrophic strain of E Coli that can be  
used with plasmids with T7 promoter. Preferably BL21 (DE3). Can  
anybody direct me to a bank, lab or were to buy it? Thnxs