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Populations of Escherichia coli Z905/pPHL7, a transgenic microorganism, were heterogenic in the expression of plasmid genes when adapting to the conditions of water microcosms of various mineralization levels and structure of microbial community. This TM has formed two subpopulations (ampicillin-resistant and ampicillin-sensitive) in every microcosm. Irrespective of mineralization level of a microcosm, when E. coli Z905/pPHL7 alone was introduced, the ampicillin-resistant subpopulation prevailed, while introduction of the TM together with indigenous bacteria led to the dominance of the ampicillin-sensitive subpopulation. A high level of lux gene expression maintained longer in the freshwater microcosms than in sterile saline lake water microcosms. A horizontal gene transfer has been revealed between the jointly introduced TM and Micrococcus sp. 9/pSH1 in microcosms with the Lake Shira sterile water., (c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.)

The role of key environmental factors in adaptation of spore-forming and non-spore-forming transgenic microorganisms (TM) have been studied in model ecosystems. Model TM Escherichia coli Z905 (bearing plasmid genes of bacterial luminescence Ap (r) Lux+) has been found to have a higher adaptation potential than TM Bacillus subtilis 2335/105 (bearing genes of human alpha 2-interferon Km (r) Inf+), planned for employment as a living vaccine under varying environmental conditions. Effects of abiotic factors on migration of natural and recombinant plasmids between microorganisms under model ecosystem conditions has been estimated. The transgenic microorganisms with low copy number survived better under introduction conditions in the microcosms studied. This trend has been shown to be independent of the microcosm type and its complexity. Grant numbers: 99-04-96017, 25, 00-07-9011., (c 2001. COSPAR. Published by Elsevier Science Ltd. All rights reserved.)

We have studied the kinetic characteristics of several isolates of Escherichia coli Z905 recombinant strain after introduction of the strain into model aquatic ecosystems. Most E. coli Z905 isolates grown as batch cultures under selective conditions (0.5 microgram/ml ampicillin) showed better kinetic characteristics of growth than did related species of native microflora, which originally populated laboratory microcosms.

An experimental approach for investigation of genetically modified microorganisms (GMMO) introduced into model ecosystems to evaluate potential risk of propagation of recombinant plasmids in surrounding medium has been developed. The object of modeling was Escherichia coli Z905 strain with a recombinant plasmid with bacterial luminescence genes, which was introduced into water microcosms of different structure. The approach involves comprehensive investigation of GMMO at four hierarchical levels: molecular (retaining the structure of the plasmid and expression of cloned genes); cellular (variation of metabolic activity); population (competitive power and metabolic interactions of GMMO with indigenous microflora, migration of recombinant and natural plasmids); ecosystem (effect of GMMO and cloned genes on ecosystem parameters). The experimental evidence and theoretical estimates are intended to form grounds to develop a basic version of an ecological certificate for different GMMO variants.