The present invention addresses the problem of providing anaerobic enterobacteria that have a greater therapeutic effect at anaerobic sites such as solid tumor tissue and ischemic disease sites. Two heterologous polypeptides such as antibodies having an anti-cancer activity are effectively secreted, extracellularly, by a bifidobacterium transformed with a plasmid according to the present invention that coexpresses two heterologous polypeptides and contains two types of secretory expression cassettes, each containing, in order, promoter DNA that functions in bifidobacteria, DNA that codes for a secretory signal peptide, DNA that codes for a heterologous polypeptide, and terminator DNA that functions in bifidobacteria.
