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October 24, 2020

Science Cast

Bridging the gap between Scientists and the Public

Potential impact of GM plants to Our digestive system

5 min read
A recent study, showed that some beneficial microbes are more susceptible to pesticides as compared to harmful bacteria. The death of these microbes could upset the critical balance of the microbial community leading to disease. Some scientists argue that, glyphosate causes low toxicity, both acute, chronic and reproductive, showing its safety for use in weed control. Contrary to that, some studies also conclude even low doses of glyphosate over time can have deleterious effects in the body.

Credit: The Conversation

We all have microscopic organisms in our gut such as bacteria, fungi, archae and viruses. The have an important role in nutrients’ absorption, immune system and production of vitamins B and K. Once the balance of these micro-organisms is distrupted, cancer , inflammatory bowel diseases and other abnormalities are given room to occur.

Our gut microbes interact directly with the food we consume. Be it vegan, carbohydrate-rich or a probiotic diet like yoghurt, it changes our gut’s micro-organism composition. Why would we have things like bacteria inside us? There are ‘good’ (e.g Lactobacillus species,) and ‘bad’ bacteria (Helicobacter pylori) in our gut that need to be balanced through regulation. It is important therefore to know the impact of the agricultural (plants and animals) products we consume.

Genetically modified plants (GM plants) are plants that have been engineered to have traits that the wild (normal) type lacks. This could be drought resistance, pest resistance, fungal resistance, nutritional content or even increased chances of survival in the market e.g. tomatoes.

Climate change has turned from being a theory to a reality. Emission of greenhouse gases results in global warming with consequences such as intense drought, melting of glaciers leading to increase in water levels in water bodies, that can result in flooding and many more deleterious effects.

With such conditions, crops that can withstand these extreme conditions will become more of a necessity than an option. Therefore, in Kenya, the ban on GM crop cultivation and importation will not be up for too long, as the environmental impacts of global warming are being felt now more than ever. In due time, drought resistant, pest resistant and fungal resistant crops will be needed. This calls for more discussions not on whether the GM plants should be authorized for cultivation, but on how to manage the impact this engineered plants will have on the environment and on human health.

There is an on-going GMO versus non-GMO debate on whether genetically modified crops can have a negative impact on human health and the environment. This discussion will focus on the possible impact on the gut microbiome. Medical experts argue that the use of glyphosate-based herbicides (round-up) to control the growth of weeds during cultivation of these GM crops could have a negative effect on the gut microbiome. Some weeds have grown to be resistant to herbicides. It is true to say that most farmers have resorted to applying more rounds of round up in order to control these weeds. This happens for both GM and non-GM crops. This raises a concern on the increased use of round-up.

Glyphosate is a broad-spectrum herbicide that inhibits the enzyme 5- enolpyruvylshikimate-3-phosphate. This enzyme is involved in the shikimate pathway which is responsible for the formation of essential aromatic amino acids in bacteria, fungi, algae, archaea, some plants and protozoans. These amino acids are building blocks for important proteins in these plants and organisms, lack of which results in death of the organism.

The irony is that most of these GM crops are made herbicide resistant, however the use of round up to control weeds may result in direct exposure to these herbicides and increased dietary consumption of the herbicide residues on agricultural products. In a study, medical experts argue that increase intake of glyphosate-based herbicides in food has effects such as oxidative stress, cancer which is one of the main concerns and the inhibition of the shikimate pathway in gut microbes.

A recent study showed that some beneficial microbes are more susceptible to pesticides as compared to harmful bacteria. The death of these microbes could upset the critical balance of the microbial community leading to disease. Some scientists argue that glyphosate causes low toxicity, both acute, chronic and reproductive, showing its safety for use in weed control. Contrary to that, some studies also conclude even low doses of glyphosate over time can have deleterious effects in the body.

Another concern is on the method used to select the transformed plant cells. Introduction of the gene of interest into the plant can be done through direct delivery of DNA using a gene gun or by using a recombinant plasmid from a soil bacterium known as Agrobacterium tumefaciens. Along the way, there is introduction of antibiotics to help show if the gene has been taken up or not. This raises the question of, is there a possibility of gene transfer between these GM crops and microorganisms?

Studies reveal that even though most free transgenic DNA from GM plants are degraded by gastric, pancreatic, bile and intestinal enzymes, some free transgenic DNA can persist long enough to reach the colon where most of the gut bacteria reside. The colon is favorable for free DNA in that its less easily degraded there and can be available for uptake by microorganisms read more.

Antibiotic resistance has been a public health concern in countries that don’t plant or import GM crops and and those that do. This is when antibiotics that help treat bacterial infections are no longer effective. This is due to a lot of misuse of the antibiotics by us. It can be use of antibiotics when its not a bacterial infection, not finishing the dose, jumping doses etc. Scientists have turned to be preachers trying to educate on when to use them. -Editors Note

E. coli has been demonstrated to be easily changed by GM plants.

In an instance where clinically pathogenic bacteria such as Escherichia coli, Salmonella typhi, Bacillus subtilis acquire antibiotic resistant characteristics from horizontal gene transfer between the microbe and GM plant transgenic DNA, it will make it hard to control their growth and multiplication thus creating a public health problem.

The probability of these bacteria acquiring antibiotic resistance might be minimal due to the nuclease and proteinases present in the gut, however it is significant enough to be a point of concern because when it comes to genetics, anything and everything is possible. Researches are being encouraged to use selectable markers that encode enzymes that degrade sugars such as galactose and mannose.

On the bright side, such antibiotics like kanamycin and neomycin are of minimal clinical relevance as development of bacterial resistance diminished their antibacterial activity. The use of different antibiotics in genetic engineering from the ones used in our daily lives will remove the risk of antibiotic resistance.

In conclusion, it is clear that medics and scientists have different point of views and concerns on the consumption of genetically modified organisms or their products. Extensive and safe clinical trials on the safety of genetically modified organisms can help to clarify on whether GM crops are safe to both humans and the environment.

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