IN-SITU SURVIVAL OF GENETICALLY-ENGINEERED MICROORGANISMS IN A TROPICAL AQUATIC ENVIRONMENT

In this study, the survival of genetically engineered microorganisms ( GEMs) and their interactions with the environmental microbiota of a tr opical river was investigated. Diffusion chambers were used for the in situ survival experiments with a nonplasmid containing Escherichia co li DH1 strain and two model GEMs, E. coli JM103 containing a 2.6 kilob ase plasmid (pUCS) and E. coli DH1 with a 4.8 kb plasmid (pWTAla5'). P ure culture survival studies indicated that after a week in the enviro nment a 1.0 log(10) decrease in bacterial numbers occurred for both E. coli DH1, while a 3.0 log(10) reduction was observed for E. coli JM10 3. However, a reduction of 4.0 log(10) was observed for the E. coli DH 1 (pWTAla5') when placed in a chamber conjointly with the resident mic robiota. The data suggest that the presence of a plasmid makes no diff erence on the survival time of GEMs, whereas the presence of competing bacteria is ultimately what limits the survival time of GEMs in the e nvironment. (C) 1996 by John Wiley & Sons, Inc.