Escherichia coli O157:H7 is a highly virulent pathogenic bacterium that naturally resides asymptomatically in the digestive tract of cattle. Contamination of foods and water via manure has resulted in multiple food-borne outbreaks. Pre-slaughter control strategies using probiotic E. coli strains capable of inhibiting pathogenic E. coli have previously been explored but their success is highly dependent on the colicinogenic bacteria's ability to colonize and produce the colicin in the gastrointestinal tract. A novel approach to circumvent these limitations is being investigated. A transgenic maize line that produces colicin (E7) was developed, the seed of which will be used as feed. Two constructs were designed and used for biolistic bombardment into HiII maize callus tissue. The first construct included the entire colicin E7 (1763 bp) gene driven by a constitutively expressing promoter (CaMV35), whereas the second construct included only the immunity E7 (263 bp) gene driven by the same promoter. The immunity E7 protein binds the colicin E7 protein to prevent nonspecific activity, thereby when the immunity E7 is expressed in conjunction with the colicin E7, higher levels of expression are expected. Therefore, two separate biolistic bombardments were performed; first with the colicin E7 construct and then the colicin E7 construct together with the immunity E7 construct. The transgenic HiII callus was transformed with both construct combinations and plants were regenerated. All plants were analyzed for transgene insertion (PCR analysis) and copy number (Southern Blotting). Expression of the mRNA of the inserted transgene was detected by RT-PCR and quantified by Northern analysis. Polyclonal colicin E7 specific antibodies as well as an inhibitory activity assays was used to detect protein production and effectiveness against the pathogenic E. coli O157:H7 strain.