MICROBES IN HUMAN WELFARE class 12 biology

1. Industrial Use of Microbes

• Microbes are used to produce many commercially valuable products.
• Major industrial products include:
  • Fermented beverages
  • Antibiotics
• Industrial-scale production is carried out in large vessels called fermentors (bioreactors).

---

2. Fermented Beverages

Microorganism Used

• Yeast: Saccharomyces cerevisiae
• Also called Brewer’s yeast.

Raw Materials

• Malted cereals
• Fruit juices

Main Product

• Ethanol (Alcohol)

Metabolic Pathway

• Alcoholic fermentation (Anaerobic respiration)

Alcohol Produced

Beverage	Distillation
Wine	❌ No
Beer	❌ No
Whisky	✅ Yes
Brandy	✅ Yes
Rum	✅ Yes

Important Points

• Yeast converts sugars into:
  • Ethanol
  • CO₂
• Type of alcoholic beverage depends on:
  • Raw material used
  • Distillation process

---

3. Antibiotics

Definition

• Antibiotics are chemical substances produced by certain microbes.
• They kill or inhibit the growth of disease-causing microorganisms.

Meaning

• Anti = Against
• Bio = Life
• Together means “Against life” (against disease-causing microbes).

Importance

• One of the greatest discoveries of the 20th century.
• Revolutionized the treatment of bacterial diseases.

---

4. Penicillin

First Antibiotic

• Penicillin was the first antibiotic discovered.

Discovery

• Discovered accidentally (chance discovery).

Discovered By

• Alexander Fleming

Year of Nobel Prize

• 1945

Source Organism

• Penicillium notatum (mould)

Discovery Story

• Fleming observed that a mould was growing on an unwashed culture plate containing Staphylococci.
• Around the mould, bacteria failed to grow.
• The mould produced a chemical called Penicillin.

Full Potential Established By

• Ernest Chain
• Howard Florey

Major Use

• Widely used to treat American soldiers during World War II.

Nobel Prize (1945)

Awarded jointly to:

• Alexander Fleming
• Ernest Chain
• Howard Florey

---

5. Diseases Controlled by Antibiotics

Antibiotics have greatly reduced deaths due to:

• Plague
• Whooping cough (Pertussis)
• Diphtheria
• Leprosy

---

NEET Important Table

Product	Microorganism	Product Obtained
Bread	Saccharomyces cerevisiae	CO₂
Beer/Wine	Saccharomyces cerevisiae	Ethanol
Penicillin	Penicillium notatum	Penicillin
Swiss Cheese	Propionibacterium sharmanii	CO₂ (holes)
Curd	Lactobacillus	Lactic acid

---

Scientists to Remember

Scientist	Contribution
Alexander Fleming	Discovered penicillin
Ernest Chain	Developed penicillin for medical use
Howard Florey	Developed penicillin for medical use

---

NEET One-Liners

• Industrial production of microbes is carried out in fermentors.
• Brewer’s yeast = Saccharomyces cerevisiae.
• Yeast converts sugars into ethanol and CO₂.
• Wine and beer are produced without distillation.
• Whisky, brandy, and rum are produced after distillation.
• Penicillin is the first antibiotic discovered.
• Source of penicillin: Penicillium notatum.
• Penicillin was discovered accidentally by Alexander Fleming.
• Chain and Florey established its therapeutic use.
• Fleming, Chain, and Florey received the Nobel Prize in 1945.
• Antibiotics kill or inhibit the growth of disease-causing microorganisms.

🎯 Most Important NCERT Facts for NEET

• Fermentor = Large vessel used for industrial-scale microbial growth.
• Brewer’s yeast = Saccharomyces cerevisiae.
• Metabolic pathway for alcohol production = Alcoholic fermentation (anaerobic respiration).
• First antibiotic = Penicillin.
• Source = Penicillium notatum.
• Discovered by = Alexander Fleming.
• Nobel Prize = 1945 (Fleming, Chain, and Florey).