Abstract
An integrative cloning vector was constructed using a randomly cloned HindⅢ digested chromosomal fragment from Lactobacillus acidophilus inserted into an Escherichia coli vector, pBluescript Ⅱ SK+. We found a restriction site BglⅡ in this chromosomal fragment. The sizes of the chromosomal fragment, approximately 2kb,was sufficient to allow the double cross-over to take place. The chromosomal fragment allowed the integration of the USP45 and human insulin gene into the host chromosomal via homologous recombination.