Q.Write short notes on microbes in medicine.

Microbes serve medicine as antibiotic producers, as engineered factories for human proteins and vaccines, and as sources of vitamins, therapeutic enzymes, and probiotics.

Microbes (bacteria, fungi, and yeasts) have several well-established roles in medicine:

1. Production of antibiotics: Many antibiotics are natural or semi-synthetic products of microorganisms.

   • Penicillin, the first antibiotic discovered (Alexander Fleming), is produced by the mold Penicillium notatum/chrysogenum and is effective against Gram-positive bacterial infections.
   • Streptomycin is produced by the actinomycete Streptomyces griseus and is used against tuberculosis and other infections.
   • Other examples include tetracycline and erythromycin, also of Streptomyces origin.

2. Production of therapeutic proteins through genetic engineering: A human gene coding for a useful protein is inserted into a microbial host (commonly the bacterium Escherichia coli or yeast), which then manufactures the protein in bulk.

   • Human insulin (marketed as Humulin) was the first such recombinant pharmaceutical product, produced by E. coli carrying the human insulin gene, and is used to treat diabetes mellitus, replacing insulin earlier extracted from animal pancreas.
   • Human growth hormone (somatotropin) is similarly produced for treating growth-hormone deficiency (dwarfism).
   • Other recombinant products include interferons (antiviral/anticancer proteins) and blood-clotting factor VIII for hemophilia.

3. Recombinant vaccines: Genetically engineered yeast cells are used to produce the surface antigen of the hepatitis B virus, which is purified and used as the hepatitis B vaccine, avoiding the need to grow the actual pathogenic virus.

4. Therapeutic enzymes: Microbially produced enzymes such as streptokinase (from Streptococcus) are used clinically as clot-dissolving (clot-buster) agents in the treatment of heart attacks.

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