Q.4 Which of the following bacterial component contains “dipicolinic acid”?
(A) Endospore
(B) Capsule
(C) Flagella
(D) Pili
Dipicolinic acid is a key molecule found exclusively in bacterial endospores, contributing to their remarkable heat resistance. The correct answer to the query is (A) Endospore.
Correct Answer
Endospore (A) is the bacterial component that contains dipicolinic acid, comprising 5-15% of its dry weight. This compound, often complexed with calcium ions, dehydrates the spore core and stabilizes DNA, enabling survival under extreme heat and other stresses in genera like Bacillus and Clostridium.
Option Explanations
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Endospore (A): Dormant, resistant structures formed by certain bacteria; dipicolinic acid (DPA) binds water and protects genetic material, making spores viable for years.
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Capsule (B): Polysaccharide layer outside the cell wall for protection against phagocytosis and desiccation; no dipicolinic acid involvement.
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Flagella (C): Protein filaments (flagellin) for motility toward nutrients; unrelated to dipicolinic acid or resistance mechanisms.
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Pili (D): Hair-like structures for adhesion or DNA transfer (conjugation); composed of pilin protein, lacking dipicolinic acid.
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Biological Role of Dipicolinic Acid
Dipicolinic acid enhances endospore resilience by reducing core water content and preventing DNA damage from heat or UV. Mutants without DPA show reduced heat tolerance, confirming its critical function beyond other factors like small acid-soluble proteins.
