Toxins of One Bacterial Species Could Lead To the Genetic Diversity of Other Bacteria


Toxins produced by bacteria as a defense mechanism can mutate target bacteria and help them survive and contribute to antibiotic resistance.

According to a study published in eLife, competitive encounters between bacterial cells could profoundly affect bacterial populations’ evolution. The research found that when bacterial cells come into contact, they often produce toxins as a defense mechanism. 

Generating Antibiotic Resistance

Although it is known that the bacteria producing these toxins have a competitive advantage, exactly how the toxins affect the recipient cells is less clear. Lead author Marcos de Moraes, Postdoctoral Scholar at the University Of Washington School Of Medicine, Seattle, US, explains:

“Undergoing intoxication is not always detrimental for cells – there are scenarios in which encountering a toxin could provide a benefit, such as generating antibiotic resistance […] we wanted to study the effects of a toxin that alters DNA beyond that of cell death and see how it impacts the surviving recipient cells it targets.” 

The team began by studying a toxin called DddA (double-stranded deaminase A), found in a bacterial species called Burkholderia cenocepacia. DddA removes chemical groups called amines from DNA, causing a specific change in the genetic code.

Widespread Mutations

To understand how DddA kills bacterial cells, the team looked at how a large dose of the toxin affects chromosomes in Escherichia coli (E. coli). They found that DddA caused rapid disintegration of chromosomes and the breakdown of DNA replication. Additionally, when they sequenced the DNA before it had disintegrated, they found widespread mutations consistent with the types of chemical changes DddA can make.

Microbial toxins are toxins produced by microorganisms, including bacteria and fungi. Microbial toxins promote infection and disease by directly damaging host tissues and by disabling the immune system. Some bacterial toxins, such as Botulinum neurotoxins, are the most potent natural toxins known. However, microbial toxins also have important uses in medical science and research. 

Damage Tissues and Disable the Immune System

Currently, new methods of detecting bacterial toxins are being developed to isolate better and understand these toxins. Potential toxin research applications include combating microbial virulence, the development of novel anticancer drugs and other medicines, and the use of toxins as tools in neurobiology and cellular biology.

Bacterial toxins, which are produced by certain bacteria, are potent human poisons. Bacterial toxins damage tissues and disable the immune system, causing acute food poisoning symptoms (e.g., vomiting, nausea, diarrhea, lightheadedness). When bacterial toxins reach organs, such as the kidney or the liver, the central nervous system, or the peripheral nervous system, they can cause serious damage or even death.

Food workers in all sectors of the food industry (e.g., hospitality, food retail, transport and distribution, health and community, food processing) must be aware of bacterial toxins and the risk they pose to consumers. All Food Handlers must be adequately trained in food safety and safe food handling techniques to prevent food from becoming contaminated with harmful microorganisms like bacteria or their toxins. 

Understanding bacterial toxins in food

 Bacterial toxins are broadly classified as either exotoxins or endotoxins.

Exotoxins are generated and actively secreted, while endotoxins remain part of the bacteria. Usually, an endotoxin is part of the bacterial outer membrane. It is not released until the bacterium is killed by the immune system, which can cause severe inflammation and even lead to sepsis.

Exotoxins are highly potent and can cause significant damage to the host by destroying cells or disrupting normal cellular metabolism. Exotoxins may be secreted, or, like endotoxins, may be released when the bacterium cell is broken down in the body. These toxin-producing bacteria are more likely to cause severe symptoms of food poisoning, long-term health complications, and death.

Preventing Food Poisoning From Bacterial Toxins

Many bacterial toxins, including those produced by Staphylococcus aureus, are heat-stable or heat resistant, meaning the cooking process does not destroy them. Suppose food contaminated with toxin-producing bacteria is cooked. In that case, the bacteria are killed. Still, the food remains contaminated with toxins that can cause food poisoning or more severe conditions, such as pneumonia, urinary tract infection, or kidney failure.

This means the only way to protect against food poisoning from bacterial toxins is to control the conditions in which high-risk foods like meat, poultry, seafood, and dairy are handled. Like all bacteria, toxin-producing bacteria need certain things to live, such as nutrients and moisture. High-risk foods possess these in spades, which makes them targets for bacteria and other harmful microorganisms.


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