GMO antibiotic resistance has been found persistently in sewage sludge. Sewage sludge that is used for fertilizer and is mixed with soil to grow food plants can have a negative effect on human health. The key to understanding that genes for antibiotic resistance in genetically modified feed can cause pathogens with the same antibiotic resistance to occur in humans is that genes can be transferred from one bacterial species to another bacterial species.
Gene from feed such as e.g. GMO corn can be fed to poultry or pigs. GMO corn contains genes that code for antibiotic resistance. E.g. nptII gene which codes for the neomycin phosphotransferase enzyme, which gives the cell kanamycin resistance and which has been inserted into 17 different varieties of GMO maize, such as MON810, MON863 and MON87460. Antibiotic resistance from the nptII gene is also inserted into 27 varieties of GMO potato and many other GMO food and fodder plants.
Antibiotic resistance coding genes are used in GMO development to be able to develop bacterial strains that will transfer GMO DNA to plant cells to create GMO plant cells, which can then be cultivated until they become GMO plants. Selection for these occurs through the use of antibiotics that carry the bacteria with successfully inserted small circle of GMO DNA is resistant to. Subsequently, those plant cells infected with small circles of GMO DNA from bacteria will survive the use of kanamycin. GMO plants with antibiotic resistance to kanamycin will then grow.
It has been found in research that GMO genes such as the nptII gene for antibiotic resistance from eaten GMO feed can survive the digestive system and water treatment plants. This makes it possible for this GMO DNA to be taken up by other bacterial species and becomes part of their functioning DNA. Potential for bacterial transformation events where bacteria take up DNA in the environment is present. This loose DNA is called eDNA (environmental DNA) and is found outside the cells in water and soil. This means that the gene for kanamycin resistance can be transferred from GMO feed to fertilizer and from there be taken up by other bacteria that may be in or on the food plants such as lettuce.
Antibiotic resistance in bacteria is increasing globally, the concern is a world where infectious bacterial diseases are immune to treatments with antibiotics. All increases in antibiotic resistance are signs of the growing danger. Antibiotics fed to livestock such as chicken, pigs and cattle have led to increasing antibiotic resistance in manure. But also antibiotic resistance from genetically modified crops used as food and feed can lead to new antibiotic resistance that is transferred from GMO digestion to manure and from manure and soil to other bacteria and to the leaves of cultivated food plants such as lettuce.
Kanamycin belongs to the antibiotic family that includes streptomycin, gentamycin, tobramycin, all three are used in human medicine, and where cross-resistance has been demonstrated within this family against antibiotics. The GMO Ampicillin marker gene should confer resistance to ampicillin. However, it has been shown that the GMO Ampicillin marker gene has, after mutations, created a gene that forms resistance to several antibiotics, some of which were/are important antibiotics. Microbes with antibiotic resistance are generally undesirable. They can form infections and they can transfer their gene for antibiotic resistance to other infectious bacteria (pathogens). GMO crops with antibiotic resistance contribute to the uncertainty about GMOs as food and feed.
Smith SD, Colgan P, Yang F, Rieke EL, Soupir ML, Moorman TB, et al. (2019) Investigating the dispersal of antibiotic resistance associated genes from manure application to soil and drainage waters in simulated agricultural farmland systems. PLoS ONE 14(9): e0222470.