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 DH7 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 log,, decrease in bacterial numbers occurred for both E. coli DH1, while a 3.0 log,, reduction was observed for E. coli JM103. However, a reduction of 4.0 log,, 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. 0 7996 by John Wiley & Sons, Inc.

FITNESS OF GENETICALLY MODIFIED MICROORGANISMS In situ (RIVER WATER)

“…3.17X10 11 1.99X10 10 2.31X10 5 1.69X10 4 2.3X10 3 ‫ــــ‬ ‫ـــــ‬ ‫ـــــ‬ MAM2A 7.28X10 14 3.9X10 10 2.81X10 5 9.68X10 4 3.7X10 3 1. Alvarez et al (1996) suggested that the presence of competing bacteria may limit the survival time of GMMs in the environment. Similar results have been described previously, McClure et al, (1991) found that the level of the introduced strain declined rapidly from 1.8x10 8 to 4.7x10 5 after 6 days, the population of the introduced strain then remained stable for the next 10 days.…”

“…Kargatova et al (2001) noted a decrease in cfu/ml to 10 2 with in a week. Alvarez et al, (1996) found differences in survival rates between GEMs and suggested that some GEMs are less resilient in the environment. Hong et al, (1996) found that number of 2.4-D-degrading bacteria were declined in natural river water.…”

“…One should not try to predict survival times of a genetically engineered microorganism based on experiments conducted with another. Thus GEMs must be evaluated on an individual basis prior to their release into the environment (Alvarez et al, 1996).…”

“…In contrast, Kluepfel et al (1991)were not able to detecte transfer of Tn7:: LacZY to microbial member of the rhizosphere. Prosser (1994) don't found evidence for transfer of the chromosomally encoded marker gene to the indigenous microflora, Alvarez et al (1996) noted that no transfer of genetic information from GEMs.…”

“…An accidental or deliberate release of genetically engineered microorganisms into the environment can be a possible source of biological contamination of ground or surface waters. Although there seem to be many promising applications of GMMs in agriculture, industry, and medicine, their use has been limited so far by environmental concerns (Alvarez, et al, 1996). Fundamental concerns regarding GMMs in the environment include the ability of these organisms to survive, to compete with the indigenous microbiota, and the possible transfer of their manipulated DNA to other microorganisms (Demirtas, et al, 2006).…”