Klebsiella oxytoca P2(pC46), an ethanol-producing recombinant, has been evaluated in fermentation of maltose and starch. The maximum ethanol produced by P2(pC46) was 0.34 g ethanol/g maltose and 0.38, 0.40, or 0.36 g ethanol/g starch in fermentation of 1, 2, or 4% starch, representing 68, 71, and 64% the theoretical yield.:The pC46 plasmid transformed to cells of K. oxytoca P2 reduced the ethanol production from maltose and starch. In fermentation of starch after its digestion at 60 degrees C for 24-h, in two-step fermentation, the time for maximum ethanol production was reduced to 12-24 h and the theoretical yield was around 90%. The increase in starch concentration resulted in lower alpha-amylase activity but in higher pullulanase activity. The high activity and thermostability of the amylolytic enzymes from this transformant suggest that it has a potential for amylolytic enzymes source.