Question

What can you tell about the microbiota of the large intestine? It is made of

1. aerotolerant anaerobes
2. strict aerobes
3. alkaliphiles
4. acidophiles
5. microaerobes

Answer 1

Answer is A) aerotolerant anaerobe

Microbe level in large intestine is about 1012/ g dryweight, that include about 400 bacterial species. Most of them are anaerobes. Aerotolerant anaerobes are microbes which are exclusively anaerobis but are not harmed by oxygen (insensitive to presence of oxygen). eg- lactobacillus,enterobacteriaceae. The microflora has an important metabolic role, such as the synthesis of vitamins such as vitamin K. Also the microbes in intestine have a protective role preventing exogenous microbial growth.

Strict aerobes can live only in the presence of oxygen (eg-mycobacterium tuberculosis)

Acidophiles are microbes that grow at an optimum pH ie below 7 (Bacillus acidocaldarius)

Alkaliphiles grow their best under alkaline pH above 7 (eg-nitrobacter)

Microaerobes require a reduced oxygen concentration (5-10%) for their growth (eg-Helicobacter pylori)