In situ survival of genetically engineered microorganisms in a tropical aquatic environment

Abstract

In this study, the survival of genetically engineered microorganisms (GEMs) and their interactions with the environmental microbiota of a tropical river was investigated. Diffusion chambers were used for the in situ survival experiments with a nonplasmid containing Escherichia coli DH1 strain and two model GEMs, E. coli JM103 containing a 2.6 kilobase plasmid (pUC9) and E. coli DH1 with a 4.8 kb plasmid (pWTAla5′). Pure culture survival studies indicated that after a week in the environment a 1.0 log10 decrease in bacterial numbers occurred for both E. coli DH1, while a 3.0 log10 reduction was observed for E. coli JM103. However, a reduction of 4.0 log10 was observed for the E. coli DH1 (pWTAla5′) when placed in a chamber conjointly with the resident microbiota. The data suggest that the presence of a plasmid makes no difference on the survival time of GEMs, whereas the presence of competing bacteria is ultimately what limits the survival time of GEMs in the environment. © 1996 by John Wiley & Sons, Inc.