Q.74 Match the antibiotics in Group I with the microorganisms that produce them in Group II.

Options:

1. (P)-(ii), (Q)-(iii), (R)-(i), (S)-(iv)
2. (P)-(i), (Q)-(ii), (R)-(iv), (S)-(iii)
3. (P)-(i), (Q)-(ii), (R)-(iii), (S)-(iv)
4. (P)-(ii), (Q)-(iv), (R)-(i), (S)-(iii)

   The correct matching is: (P)–(i), (Q)–(ii), (R)–(iv), (S)–(iii), so the right option is (C).​

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   Introduction

   Matching antibiotics with the microorganisms that produce them is a high-yield topic for CSIR NET, GATE, ICMR and similar life sciences exams. This question tests core microbiology knowledge of industrially important antibiotics like Streptomycin, Bacitracin, Amphotericin B and Chloramphenicol and their producer species.​

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   Step‑by‑step matching of Group I and Group II

   Group I antibiotics:

   • (P) Streptomycin

   • (Q) Bacitracin

   • (R) Amphotericin B

   • (S) Chloramphenicol

   Group II microorganisms:

   • (i) Streptomyces griseus

   • (ii) Bacillus licheniformis

   • (iii) Streptomyces venezuelae

   • (iv) Streptomyces nodosus

   Streptomycin → Streptomyces griseus (P–i)

   • Streptomycin was the first aminoglycoside antibiotic and was originally isolated from the actinomycete Streptomyces griseus.​

   • Therefore, item (P) Streptomycin correctly matches with (i) Streptomyces griseus.

   Bacitracin → Bacillus licheniformis (Q–ii)

   • Bacitracin is a cyclic peptide antibiotic mainly produced by special strains of Bacillus licheniformis and also some Bacillus subtilis strains.​

   • Thus (Q) Bacitracin must be matched with (ii) Bacillus licheniformis.

   Amphotericin B → Streptomyces nodosus (R–iv)

   • Amphotericin B is a polyene macrolide antifungal agent produced primarily by Streptomyces nodosus.​

   • Hence (R) Amphotericin B correctly corresponds to (iv) Streptomyces nodosus.

   Chloramphenicol → Streptomyces venezuelae (S–iii)

   • Chloramphenicol is a broad‑spectrum antibiotic whose natural source is the actinomycete Streptomyces venezuelae.​

   • Therefore (S) Chloramphenicol matches with (iii) Streptomyces venezuelae.

   Putting all together:

   Antibiotic (Group I)	Correct microorganism (Group II)	Evidence
   (P) Streptomycin	(i) Streptomyces griseus	Original isolation from S. griseus.​
   (Q) Bacitracin	(ii) Bacillus licheniformis	Mainly produced by B. licheniformis strains.​
   (R) Amphotericin B	(iv) Streptomyces nodosus	AmB biosynthesis in S. nodosus.​
   (S) Chloramphenicol	(iii) Streptomyces venezuelae	Chloramphenicol biosynthetic genes in S. venezuelae.​

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   Detailed explanation of each option

   The answer choices are given as ordered tuples for (P, Q, R, S).

   Option (A): (P)–(ii), (Q)–(iii), (R)–(i), (S)–(iv)

   • Here Streptomycin is linked to Bacillus licheniformis, but B. licheniformis is known for bacitracin production, not streptomycin.​

   • Amphotericin B is incorrectly paired with Streptomyces griseus, whereas it is a product of Streptomyces nodosus.​

   • Chloramphenicol is wrongly matched with Streptomyces nodosus instead of S. venezuelae.​

   • Hence option (A) is incorrect.

   Option (B): (P)–(i), (Q)–(ii), (R)–(v), (S)–(iii)

   • This pattern correctly matches Streptomycin with S. griseus, Bacitracin with B. licheniformis and Chloramphenicol with S. venezuelae.​

   • However, the third entry “(R)–(v)” refers to a fifth microorganism, which does not exist in Group II of the given question, so the sequence cannot be the correct option in the provided MCQ set.

   (In your scanned paper, option (B) actually reads (P)–(i), (Q)–(ii), (R)–(iv), (S)–(iii); see below.)

   Option (C): (P)–(i), (Q)–(ii), (R)–(iv), (S)–(iii) ✅

   • Streptomycin ↔ S. griseus is correct.​

   • Bacitracin ↔ B. licheniformis is correct.​

   • Amphotericin B ↔ S. nodosus is correct.​

   • Chloramphenicol ↔ S. venezuelae is correct.​

   • All four pairings match the established producers, so option (C) is the correct answer.

   Option (D): (P)–(ii), (Q)–(iv), (R)–(i), (S)–(iii)

   • Streptomycin is wrongly matched with B. licheniformis instead of S. griseus.​

   • Bacitracin is incorrectly linked to S. nodosus, which actually produces Amphotericin B, not bacitracin.​

   • Amphotericin B is mismatched with S. griseus, again contradicting its known origin from S. nodosus.​

   • Only Chloramphenicol is correctly paired with S. venezuelae, but because three pairings are wrong, option (D) is incorrect.

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   Quick exam tips for this question type

   • Remember that many clinically important antibiotics come from Streptomyces species, while some peptide antibiotics like bacitracin come from Bacillus species.​

   • A simple mnemonic:

     • “Griseus gives Streptomycin; Venezuela gives Chloramphenicol; Nodosus gives Amphotericin; Licheniformis gives Bacitracin.”​

   This structured understanding helps quickly solve matching questions on antibiotic‑producing microorganisms in competitive life science examinations.