#antibiotic production

Aptitude and Reasoning - Part 2

In a fed batch process for the production of an antibiotic, the dissolved oxygen (DO) level was found to be falling belo

The principle of quantitative reasoning explains that ratio, percentage and series logic determine correct calculation. Hence decrease the feed rate fits best because it meets mathematical and logical criteria, as documented in authoritative sources on aptitude and reasoning.

Ref: Agrawal, Quantitative Aptitude for Competitive Examinations, Chapter 5, Logical Reasoning and Probability, covers ratios, percentages, series completion, time-distance and analytical reasoning explaining problem-solving strategies for competitive assessments.

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Basic Applied Biology

Maximum antibiotic producers belong to genus:

Genus Streptomyces, order Actinomycetales comprising filamentous Gram-positive bacteria with high GC content around 72 percent, represents most prolific source of bioactive natural products, accounting for more than two-thirds of clinically relevant antibiotics including streptomycin discovered by Waksman 1943, tetracycline, erythromycin, chloramphenicol, rifamycin and avermectin precursor of ivermectin. Large linear chromosome 8 to 10 Mb encodes 20 to 40 cryptic biosynthetic gene clusters per strain encompassing type I modular and type II iterative polyketide synthases, non-ribosomal peptide

Ref: Berdy J Antibiotics 2005; Watson Molecular Biology of the Gene 7th ed. Actinomycete secondary metabolism; NIH actinobacteria review.

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Basic Applied Biology

Antibiotic production by Streptomyces occurs mainly during:

Streptomycetes exhibit biphasic growth kinetics clearly separating primary trophophase from secondary idiophase, a regulatory hallmark crucial for industrial antibiotic production. During logarithmic growth phase when carbon, nitrogen and especially phosphate are abundant, global regulators like DasR respond to N-acetylglucosamine, PhoP to phosphate, and GlnR to nitrogen repressing biosynthetic gene clusters encoding polyketide synthases PKS and non-ribosomal peptide synthetases NRPS to prioritize biomass accumulation, DNA replication and protein synthesis. As nutrients become limiting at onse

Ref: Berdy J Antibiotics 2005 Streptomyces secondary metabolites; Alberts Molecular Biology of the Cell 6th ed. Ch secondary metabolism.

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Microbial Classification

Most antibiotics are produced by members of

Order Actinomycetales within phylum Actinobacteria dominates natural antibiotic discovery because of extensive secondary metabolism encoded by large modular polyketide synthase and nonribosomal peptide synthetase gene clusters. Genus Streptomyces isolated from soil produces approximately two-thirds of clinically used antibiotics including streptomycin, tetracycline, chloramphenicol, and erythromycin. Competitive soil environment drives chemical warfare through antimicrobial secretion. While Bacillus and Pseudomonas produce some antimicrobials, actinobacterial fermentation screening historicall

Ref: Campbell Biology 12th ed., Chapter 27 Actinobacteria antibiotics Streptomyces; Brock Biology Microorganisms 15th ed., antibiotic producers secondary metabolites

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