4.3. Safety aspects specific to GMMs
The recombinant DNA techniques used for modification of plants are similar to those used for design of genetically modified microorganisms. As it was already mentioned above distinct genetic characteristics of microorganisms are implicated and should be taken into account for safety reasons. Microorganisms applicable for food production are Gram + and Gram – bacteria, yeasts and filamentous fungi. Their genome and recombinant genetic technologies have differences, although some common techniques exist as well.
Use of homologous recombination in bacteria has a major advantage, because an integration site can be applied by design and undesirable DNA can be easily removed. Thus, a homologous genes system for the selection and maintenance of introduced DNA can be designed together with development of appropriate selection methods, compatible with safe food use. These features facilitate good control over genetic modification procedures.
Recently the safety evaluation of GMMs is enhanced by availability of genome sequence data of some bacteria and yeast. This acquisition of the complete genome sequence for particular microorganism is a realistic scientific base for evaluation and assessment of a particular gene technology. Development of post-genome analytical methodology and technical devices give reliable opportunity for analysis of gene expression at the level of the entire genome. Success of micro array DNA technology allowed investigation of all genes of the genome by means of nucleic acid probes. Thus, the presence of individual genes and gene expression in different strains and environments can be demonstrated. Advance in proteomics allows proteins isolated from the whole cells to be separated by two-dimensional gel electrophoresis and to be analyzed. In this way a comparison could be made between strains from different environments. Using mass spectrometry, an individual protein could also be identified and so facilitate the relating of separated protein spots to specific genes. Microorganisms used in food processing could be found viable in the end product and could be introduced into the consumer. That is why a potential for interaction (direct or indirect) between organisms and consumer actually exists. For this reason it is very important to prove with certainty that the microorganisms used in food processing are not pathogenic, toxigenic or allergenic and the genetic modification do not alter their safe status. In this respect the fate of GMMs consumed and their impact on gastrointestinal tract and gut microflora has to be taken into account. Here it is important to note that effect of GMMs should be considered also on the level of the animal health, having in mind the influence on humans through nutrition. One of the most general concerns that have been expressed is the possibility for transfer of modified gene sequences to gut microorganisms or host cells. Rare acquisition of diet-derived DNA fragments can not be ruled out and the possible impact of genes not normally present in ruminant diets should be considered.
