The influence of GMO feed on ecosystem stability of the gastrointestinal tract in different species - a review

Research on the human gut microbiota has been rapidly developing in recent years. Microbiota composition is now well recognized as linked to non-communicable chronic diseases and other health problems. However, science has not reached the point of understanding, how specific changes in microbiota composition affect health and what represents a "healthy" microbiota. Transgenic plants are plants that have been genetically modified (GM) using recombinant DNA technology. These plants are mainly used as feedstuff. An important issue is connected with the persistence of recombinant DNA and 'novel' protein in the digestive tract and tissues of food-producing animals. The fate of DNA in the gastrointestinal tract of the animals has not been extensively investigated, probably due to the generally held dogma that food DNA could not resist low stomach pH and degradation by pancreatic nucleases and brush-border nucleosidases. The majority of DNA is really degraded within the animal's digestive system; however, this process is incomplete and some remaining small fragments of DNA can appear throughout the gastrointestinal tract. Fragments of DNA were detected in the contents of the small intestine, the cecum, the large intestine, or the feces of mice, also in muscle, liver, spleen, and kidney tissue in chickens. However, there were too small to transfer genetic information. There is a relatively limited chance that transgenes will be transferred from GM plants to other Eukaryotes. However, with regard to microorganisms, it is theoretically possible. It is well established that bacteria possess sophisticated mechanisms for the acquisition and rearrangement of genetic material and thus the quantitative and qualitative composition of microbiota in different segments of the digestive tract is changing. Another issue is the horizontal gene transfer with a particular focus on antibiotic resistance genes. Safety of incorporating antibiotic-resistance markers into GM plants has been a matter of public debate. In the past antibiotics were used in genetic modification as markers for the selection of successfully transformed organisms; however, these genes are not currently used.