Question

The bacterium (Clostridium botulinum) that causes botulism is a/an

(A) Obligate aerobe

(B) Facultative aerobe

(C) Facultative anaerobe

(D) Obligate anaerobe

Answer 1

Hint: Clostridium botulinum is an organism that can survive in the presence of oxygen, can use oxygen or perform aerobic respiration, but can also survive without oxygen via fermentation or anaerobic respiration.

Complete answer:

The bacterium (Clostridium botulinum) that causes botulism is an obligate anaerobe. Clostridium botulinum is a Gram-positive, rod-shaped, spore-forming bacterium. It is an anaerobe, which means that oxygen is poisonous to the bacterial cells. However, C. botulinum tolerates traces of oxygen thanks to the enzyme SOD (Super Oxide Dismutase), which is a crucial antioxidant defense in nearly all cells exposed to oxygen that is why it is considered as obligate anaerobe. C. botulinum is merely ready to produce the neurotoxin during sporulation, which may only happen in an anaerobic environment. During an unfavorable growth environment, other bacterial species produce spores to preserve the organism's viability and permit survival in a dormant state until the spores are exposed to favorable conditions.

The neurotoxin can cause a severe flaccid paralytic disease in humans and other animals also and is the most potent toxin known to humankind, natural or synthetic, with a lethal dose of 1.3–2.1 ng/kg in humans.

C. botulinum is a diverse group of pathogenic bacteria initially grouped by their ability to produce botulinum toxin and now known as four distinct groups, C. botulinum groups I–IV, also as some strains of Clostridium butyricum and Clostridium baratii, are the bacteria liable for producing neurotoxin.

So, the correct answer is, 'Obligate anaerobe' that is option D.

 

Note:

- C. botulinum was first recognized and isolated in 1895 by Emile van Ermengem from home- cured ham implicated during a botulism outbreak.

-  ̣Botulism poisoning can occur thanks to preserved or home- canned, low-acid food that wasn't processed using correct preservation times or pressure.