The plasmid pAL205 encodes an alginate lyase gene of Pseudomonas sp. OS-ALG-9, fused in frame to the beta-galactosidase alpha-peptide gene. The alginate lyase (Aly) expressed in Escherichia coli (pAL205) was significantly secreted into the medium by the addition of glycine. The extracellular enzyme isolated from the culture of E. coli JM109 (pAL205) was purified over 15,000-fold by successive chromatography and subjected to amino acid sequence analysis. The sequence determined was identical to that of the intracellular protein. Since the activity and molecular size of the extracellular Aly is identical to the intracellular protein and to the Aly isolated from Pseudomonas, the glycine does not affect or modify the Aly during its leakage into the medium.