Do GMOs Negatively Affect Microbes?
Altering Soil Microbe Populations with Genetic Engineering
Researchers are still looking into how genetically modified (GMO) crops affect good microbes in the soil and ecosystems nearby. The effects can differ depending on the type of GMO crop, the changed trait, and the environmental conditions. Here are some key considerations:
Root Exudates and Microbiome: Plants release substances known as root exudates into the soil, influencing the composition and activity of soil microbial communities. Some GMO crops, especially those engineered for herbicide tolerance or pest resistance, may have altered root exudates. These changes can indirectly affect the soil microbiome by promoting or inhibiting specific microbial populations' growth. (Mandal et al, 2020)
[Scientists] attribute the reduction in enzyme activities in the soil of transgenic cotton to decreased enzyme synthesis by microorganisms or to a competition between the Cry1Ac proteins and the CpTI enzymes for adsorption sites in soil. A subsequent field assessment showed a significant increase in the DHA activity in soil growing Bt cotton and its significant inhibition after residue incorporation in soil. Thus, similarly to its effects in the greenhouse, Bt cotton inhibited the growth and activities of soil microorganisms. (Lebedev et al, 2022)
Pesticide Use: It is claimed that GMO crops engineered for pest resistance often require fewer chemical pesticide applications. As we learned in our previous article about GMO crops, pesticide usage has actually increased over the past 20 years. Many pesticides kill off microbial populations (both good and bad microbes).
Herbicide-Tolerant Crops: GMO crops engineered for herbicide tolerance are designed to withstand herbicides like glyphosate (commonly used with glyphosate-resistant crops). In 2010, glyphosate was patented for its antibiotic effects. Thus, its increased use causes die-off in the soil and on the plants exposed to it. Glyphosate is used in almost all conventionally grown no-till operations as a “chemical mowing” program. It is also used to speed up the drying of crops for harvest. Lastly, the maker of glyphosate is in the middle of a major class-action lawsuit for various types of cancer.
Don Huber, Ph.D, has exposed glyphosate for many of its fraudulent claims as ‘'safe” and having a “short half-life,” documenting its long-lasting effects in the soil. Huber has documented the following:
Glyphosate increases disease in plants and animals
Glyphosate may be linked to many health problems
Glyphosate wipes out beneficial soil microbes, leaving the soil open to disease
Huber has received criticism and accusations of falsifying data from GMO proponents. He can still be found speaking at various organic and anti-GMO gatherings.
Crop Rotation and Biodiversity: The adoption of GMO crops may affect crop rotation patterns and overall farm biodiversity. Crop rotation can influence the diversity of beneficial soil microbes. For instance, continuous cultivation of a single GMO crop type might change soil microbial populations. This is the main reason for crop rotation, as pathogens in the soil could gather strength and lead to diseases in the soil and in plants. As Lebedev et al. discussed in the paper (cited below), different GMO crops secrete different exudates that affect enzyme production and phosphorus availability, which have residual effects in the soil.
Secondary Effects: Alterations in pest populations due to GMO crops can have secondary effects on soil ecosystems. Logic would tell us that if the number of pests in an area goes down because of Bt (Bacillus thuringiensis) insect-resistant crops, this could affect the animals that eat the pests and the organisms that break them down. Sure enough, “Bt corn can adversely affect non-target insects if they are closely related to the target pest, as is the case with Monarch butterflies.” (Peairs, 2013)
It's crucial to remember that GMO crops impact beneficial bacteria in a complicated and context-dependent way. Research in this area is still developing, and the results can differ based on particular crop varieties, agricultural techniques, and regional environmental factors. There could be more factors, but the research is lacking.
While GMO crops may affect beneficial bacteria directly or indirectly, the precise results are still being studied and may change depending on a number of variables. Only true organic practices will be the ideal farming practices that can help lessen the risk of adverse effects on the microbial communities in the soil. If you don’t want to support GMOs, it is getting more difficult to tell which foods you can purchase since labeling is not required. GMOs are not allowed in certified organic foods, but traces of glyphosate have been detected in many organic foods and in the air, groundwater, runoff, river basins, and soil in several states for over a decade. You are best off growing your own organic crops at home. Otherwise, know your farmer!
And we are only looking at the indigenous microbes in the field. It will be years before research is available on the genetically modified microbes being applied today. Yes, that is correct! GMO microbes are being applied to crops across the country. Time will tell what impact they have on soil microbe populations.
Sources
Lebedev V, Lebedeva T, Tikhonova E, Shestibratov K. Assessing Impacts of Transgenic Plants on Soil Using Functional Indicators: Twenty Years of Research and Perspectives. Plants. 2022; 11(18):2439. https://doi.org/10.3390/plants11182439
Mandal, A., Sarkar, B., Owens, G., Thakur, J., Manna, M., Niazi, N. K., Jayaraman, S., & Patra, A. K. (2020). Impact of genetically modified crops on rhizosphere microorganisms and processes: A review focusing on Bt cotton. Applied Soil Ecology, 148, 103492. https://doi.org/10.1016/j.apsoil.2019.103492
Peairs, F.B. Bt Corn: Health and the Environment – 0.707. Colorado State University Extension. 2013. https://extension.colostate.edu/topic-areas/agriculture/bt-corn-health-and-the-environment-0-707-2/#:~:text=Bt%20corn%20can%20adversely%20affect,the%20case%20with%20Monarch%20butterfly.