DEVELOPMENT OF A GENETIC-TRANSFORMATION SYSTEM FOR AN ALGA-LYSING BACTERIUM

Four marine bacteria, Alteromonas sp, strains A27, A28, A29, and A30, that lyse the diatom Skeletonema costatum NIES-324 were isolated from coastal seawater samples. They were also able to lyse the diatoms Tala ssiosira sp, and Eucampia zodiacs and the raphidophycean flagellate Ch attonella antiqua, Cryptic indigenous plasmids, designated pAS28 and p AS29, were detected in Alteromonas sp, strains A28 and A29, respective ly. These plasmids appeared to be similar based on size and restrictio n site analysis, A shuttle vector that replicates in Escherichia coli and Alteromonas sp. strain A28 was constructed by fusing pAS28 and E. coli vector pCRIIc. The 16-kbp chimeric plasmid, designated pASS1, had the ability to transform strain A28 at a frequency of 10(6) transform ants per mu g of DNA. Deletion analysis of pASS1 showed that the 4.7-k b EcoRI-HindIII region of pAS28 was essential for plasmid maintenance in strain A28, This EcoRI-HindIII fragment contained an open reading f rame which appeared to encode a 708-amino-acid protein.