JUL 21, 2017 12:14 PM PDT

No link between biopesticide and food poisoning

WRITTEN BY: Kerry Evans

Researchers at the University of Exeter published an impassioned defense of the biopesticide Bacillus thuringiensis, refuting a report by the European Food Safety Authority (EFSA) that the bacterium caused a bout of food poisoning in 2012.

The EFSA report concluded that B. thuringiensis was essentially equivalent to B. cereus, a bacterium that does indeed cause food poisoning.

B. thuringiensis is a popular biopesticide

Image: Alchetron

Can biopesticidal strains of B. thuringiensis (Bt) make humans sick? The study authors report that it takes over 108 spores to potentially make a small mammal sick - the human equivalent is about 1011. Get this - human volunteers who consumed 1 gram of a Bt-based pesticide for 5 days suffered no ill effects. The fact is, humans don’t ever encounter this many spores in their everyday life.

Can any strain of Bt make people sick? Maybe, but it’s not likely. There are only a handful of reports of infections with environmental isolates of Bt. Bt was found in infected burn wounds and in a soldier who was injured by a landmine, for example. However, these specific Bt strains were most closely related to the anthracis clade (which contains the pathogen B. anthracis).

But doesn’t Bt make an enterotoxin? This is true, but the authors note that most serious cases of food poisoning cause vomiting, the result of cereulide toxin. This toxin is made by B. cereus, not Bt. If the Bt enterotoxin were to make you sick, the bacteria would have to survive being digested by stomach acids, which it typically doesn’t. With this in mind, the researchers insist that it is phylogeny, not the ability to make enterotoxin, that best predicts whether a strain will cause food poisoning.

By phylogeny, they mean how closely related a Bt strain is to pathogens in the B. cereus group. For example, safety tests indicate that B. anthracis is over one million times more hazardous to vertebrates that biopesticidal Bt. It’s no surprise, then, that Bt strains closely related to anthracis are associated with infections in vertebrates.  

The take-home message is this - don’t jump to conclusions without critically considering the facts. According to the authors, “microbial biopesticides based on Bt are widely recognised as being among the safest and least environmentally damaging insecticidal products available. No strain produced to kill insects has been shown to cause infections or pose risks to humans."

Sources: FEMS Microbiology Ecology and Science Daily


About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
OCT 16, 2018
OCT 16, 2018
Simple Test Rapidly Diagnoses Antibiotic-resistant Infections
If we get a bacterial infection, doctors use antibiotics to treat it. But sometimes people are infected by pathogens that are resistant to drugs....
OCT 30, 2018
Drug Discovery
OCT 30, 2018
Combination of Drugs Extends Lifespan of C. elegans
In a study published in the journal Developmental Cell, a cocktail of pharmaceutical drugs were recently found to extend the life of the microscopic worm,...
NOV 25, 2018
NOV 25, 2018
Ongoing Ebola Outbreak in DRC Becomes Country's Worst Ever
On August 1, 2018, an Ebola outbreak was declared in the Democratic Republic of the Congo, which is still ongoing....
NOV 26, 2018
Health & Medicine
NOV 26, 2018
The Role of Clinical Lab Scientists
The clinical laboratory is the heart of any hospital or healthcare system. It is responsible for greater than 70% of medical diagnoses and decisions made b...
NOV 25, 2018
Drug Discovery
NOV 25, 2018
Advancing Drug Therapies for an Increasing Case of a Parasitic infection Among Displaced Syrians
Cases of Cutaneous leishmaniasis (CL), a parasitic disease, has increased dramatically in Syria and neighboring countries as a result of the conflict-relat...
DEC 08, 2018
DEC 08, 2018
Atrial Fibrillation, Explained
Atrial fibrillation (A-Fib) is a term you've likely heard before. You may have even been told you live with A-Fib. What exactly is this common type of...
Loading Comments...