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ASSESSING THE RISKS INVOLVED IN THE RELEASE OF GENETICALLY MANIPULATED MICROORGANISMS

Objective

MICROORGANISMS DELIBERATELY RELEASED INTO THE ENVIRONMENT AFTER RIGOROUS TESTING ARE UNLIKELY TO PROVE A DIRECT THREAT (I.E. PATHOGENS), AND PREDICTION OF SUCH RISKS IS ALMOST IMPOSSIBLE. HOWEVER, THE MAIN RISK IS THE PROSPECT OF CREATING POTENTIALLY HAZARDOUS NEW ORGANISMS FOLLOWING THE TRANSFER OF MOBILE GENES TO NATIVE BACTERIA. MANY BACTERIA CAN EXCHANGE GENETIC MATERIAL, INCLUDING PLASMIDS AND TRANSPOSONS; THEREFORE THE PERSISTENCE AND SPREAD OF BOTH THE ORGANISMS AND GENES ARE BOTH IMPORTANT AND WOULD BE AFFECTED BY A VARIETY OF SELECTIVE PRESSURES.

THIS STUDY IS EXPECTED TO GIVE FURTHER IMPORTANT INFORMATION ABOUT THE GENETICS AND GENE TRANSFER MECHANISM OF THE MICROORGANISM RHIZOBIUM WHICH IS TO BE SELECTED, AFTER APPROPRIATE MODIFICATION OF ITS GENOME, FOR THE INOCULATION OF LEGUMINOUS PLANTS.

THE METHODOLOGY DEVELOPED IN ORDER TO FOLLOW THE PERSISTENCE OF SPECIFIC STRAIN IN THE SOIL WILL BE OF PARTICULAR INTEREST FOR EVALUATING THE SPREADING OF GENETICALLY ENGINEERED IN THE ENVIRONMENT.
To investigate survival of introduced strains and their genes and to develop and assess monitoring methods, genetically marked derivatives of 2 common soil bacteria were used: Rhizobium which fixes atmospheric nitrogen in the root nodules of legumes (and has a long history) of safe and effective use as an agricultural inoculant) was used in both field and laboratory experiments; Enterobacter agglomerans which fixes nitrogen in association with cereal roots was studied in the laboratory. Strains were marked with genes conferring antibiotic resistance, either by selecting naturally occurring chromosomal mutations, or by insertion of transposon Tn5 to conjugative plasmids. In addition, native Rhizobium populations were screened for circumstantial evidence that genetic exchange occurs (over a long period) in the environment.

The Tn5 marker enabled extensive monitoring of the Rhizobium inoculant, which showed significant variation in survival in field soils of the collaborating countries. The host plant was not required for its establishment. Spread from the site of application over short distances indicated migration along extending roots; over moderate distances it was associated with standing surface water; and over greater areas by bulk soil movement. In the field, no Tn5 transfer to other Rhizobium (isolated from nodules) was found, although populations were below the level at which transfer could be detected in the laboratory. In culture, the inoculant could transfer Tn5 to Escherichia coli and E agglomerans, in addition to a range of Rhizobium species (in contrast to E agglomerans which transferred its plasmid only to closely related strains). Field populations of Rhizobium showed considerable evidence that genetic exchange between soil bacteria must occur in the long term.
THIS RESEARCH AIMS AT STUDYING THE PERSISTENCE IN AGRICULTURAL SOIL OF GENETICALLY MODIFIED BACTERIA AND THE SPREADING OF GENES CARRIED BY THESE BACTERIA TO OTHER SOIL MICROORGANISMS. THE COLLABORATIVE EFFORT (COMPRISING TWO OTHER EUROPEAN LABORATORIES) WILL BE CENTERED ON THE UTILIZATION OF DIFFERENT RHIZOBIUM SPECIES, TO BE RELEASED INTO THE FIELD. R.LEGUMINOSARUM WILL BE CHOSEN IN THIS STUDY.
AIM OF THE PROJECT IS TO INOCULATE PEAS WITH RHIZOBIUM STRAINS HAVING MARKER GENES AND FOLLOW THEIR PERSISTENCE AFTER APPLYING SELECTIVE PRESSURE FOR LONG TIME PERIODS.

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Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Institut National de la Recherche Agronomique
EU contribution
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Address
Rue de Sully
21034 Dijon
France

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Last update: 23 January 1994

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Permalink: https://cordis.europa.eu/project/id/BAP*0108

European Union, 2024