Transformed Sf9 cell line expressing antibacterial protein was constructed by using Autographa californica nuclear polyhedrosis virus (AcNPV) immediate early gene (ie1). The cell line was resistant to neomycin and expressed antibacterial protein under the control of Drosophila heat shock protein promoter. The genomic organization and expression at the transcriptional level of nuecin in the transformed cells were characterized. Nuecin was successfully expressed in the transformed cells and secreted into the media. Antibacterial activity of nuecin from the transformed cells was assayed against Escherichia coli. It indicates that nuecin secreted from the transformed cells is possible, at least in permissible concentration, to recover the cultures that have been contaminated.