The object of the invention is to provide an anaerobic enterobacterium having a higher therapeutic effect on an anaerobic site such as a solid tumor tissue and an ischemic disease site. A bacterium of the genus Bifidobacterium, which is transformed with a plasmid co-expressing two types of heterologous polypeptides and comprising two types of secretory expression cassettes each sequentially comprising a promoter DNA functioning in the bacterium of the genus Bifidobacterium a DNA encoding a secretory signal peptide a DNA encoding a heterologous polypeptide and a terminator DNA functioning in the bacterium of the genus Bifidobacterium, efficiently secretes the two types of heterologous peptides, i.e., two types of antibodies having anticancer effects, outside the bacterial cell.
