pC194Amy, a construct containing an amylase encoding gene, was introduced in Lactobacillus sanfrancisco CB1 by electroporation and the Amy gene was expressed. Amylase activity was extracellular and retained after 140 generations. The growth of the transformant with 10 g starch/L and 5 g maltose/L was similar to that of the wild type in 10 g maltose/L. L. sanfrancisco CB1 transformant harboured pC194Amy, a small DNA fragment and did not possess the native plasmid. The small DNA fragment was demonstrated to be a deletion product of pC194Amy containing the Amy sequence. L. sanfrancisco CB1 was also transformed with pGKV210, pNZ12 and pMG36e by electroporation.