Bacillus cereus is an endospore-forming bacterium that can cause food poisoning. If food has been left at room temperature too long, the endospores can begin to replicate into normal bacteria.
Bacillus Cereus & Food Poisoning
Have you ever been to a party that served food? When you first arrive, everything is fresh and at the right temperature. But as the hours pass, and you’re enjoying a room-temperature mini-quiche, you can’t help but wonder if it’s still safe. You decide to risk it, eat the quiche, and wake up in the morning regretting your decision.Food that has been left out for too long can allow a bacterium called Bacillus cereus to grow. This is different from more well-known food-poisoning bacteria, such E.
coli, Listeria, or Salmonella, which can cause large outbreaks. Like other types of infectious bacteria, B. cereus produces toxins. As the name implies, toxins are not good for you; they are proteins that make you sick.There are two types of B. cereus food poisoning. One type causes diarrhea about 4 to 16 hours after exposure.
Many different types of food, like meats, vegetables, and dairy products, can harbor this type of B. cereus. The other, less common type causes nausea about 1 to 5 hours later. This type is normally associated with rice. The main underlying factor for both types of B.
cereus food poisoning is improperly stored food.
Bacillus Cereus Morphology
Morphology describes what shape bacteria have. The most common shapes are cocci, which are round balls; bacilli, which are rods; and spirochetes, which are corkscrews. B.
cereus is classified based on how it looks under a microscope, just like most other bacteria species. Bacillus refers to bacteria that have a rod-like shape; sort of like a rectangle with rounded edges.
Bacillus Cereus Endospores
The question remains, though, how does B.
cereus cause food poisoning? It’s already been mentioned that B. cereus is found in food that has been left out too long, but where does it come from? B. cereus is found in the environment – in soil, on vegetables, in dairy products. However, it’s not the normal form of happily replicating B. cereus found on these things. B. cereus, like other closely related species, can form endospores.
An endospore is like a strong fortress that protects the bacterium’s DNA when it’s in dangerous areas. When the environment is too risky for a normal, vulnerable cell, it can enclose its DNA in an endospore to wait out the storm. Endospores cannot replicate to make new bacteria, so when the conditions change to something safe, the endospore turns back into a regular bacterium.In the case of B.
cereus, the endospores hang out in the food. Because the endospores are so resistant to heat, UV radiation, dehydration, and other things that normally kill bacteria, the endospores remain alive, even after cooking the food. If contaminated food is left out too long, the endospores can turn back into regular B. cereus, which can quickly replicate and then cause disease.
Let’s review what we’ve learned;Food poisoning can be caused by many different kinds of bacteria within the food. On the news, you normally hear about E. coli contaminating different foods. Bacillus cereus, or B. cereus, is another common cause of food poisoning. We also learned about bacteria morphology, which describes what shape bacteria have. The most common shapes are cocci, which are round balls; bacilli, which are rods; and spirochetes, which are corkscrews.
Bacillus cereus typically are bacilli, as the similar name implies.When prepared foods have been stored improperly for too long, B. cereus endospores, which are an extra level of protection for a bacterium’s DNA that appears in hostile environments and conditions, can become regular bacterial cells and reproduce.
The bacteria then produce toxins, which are proteins that make you sick, which will cause vomiting or diarrhea in the patient. To prevent B. cereus food poisoning, it’s best to always store your food at the proper temperature, heating the food enough to kill any B. cereus bacteria that’s present, and tossing any food that’s been left at room temperature too long.