Question

Chloromycetin is obtained from
a. Streptomyces griseus
b. Streptomyces venezuelae
c. Bacillus subtilis
d. Saccharomyces cerevisiae

Answer 1

Hint: Chloromycetin is also called chloramphenicol which is used as an antibiotic, and it useful for the treatment of various bacterial infections, and is also used to treat meningitis, plaque, cholera, Typhoid fever and it is also used as an ointment for conjunctivitis.

Complete answer:
- Chloromycetin was discovered when it was isolated from streptococcus Venezuelae.
- It was discovered in the year 1947.
- After identifying it’s structure, it was artificially made or synthetic antibiotics made in the year 1949.
- So as it is artificially made after the extraction, it is called a man-made antibiotic.
- It mainly acts by slowing down the synthesis of proteins by bacteria, which helps the bacteria for their survival.
- This antibiotic is important against some bacteria which include Salmonella typhi, influenza, E Coli, Neisseria and some species of staphylococcus and streptococcus species.
- Chloramphenicol obtained its FDA approval in the year 1950.
- It is obtained in many various forms, it is available as 0.5% sterile ointment and it is obtained as 1% eye drops.

Mechanism of action.
- The Chloramphenicol diffuses the bacterial cell wall and it is reversible bound to the 50s ribosome unit.
- The binding of chloramphenicol interferes with an enzyme activity called peptidyl transferase.
- Therefore this action prevents the transfer of amino acids, which in turn stop the growing peptide chains which result in the blocking of peptide bond formation.
- As a result, bacterial protein synthesis is blocked and impedes bacterial cell proliferation.

Hence, the correct answer is option (B).

Note: Chloramphenicol or chloromycetin belong to the organic compound Nitrobenzene, it contains, nitrobenzene moiety and consists of a benzene ring with a carbon-bearing nitro group, it exists as solid and it is insoluble in water.