Biology In Human Welfare Microbes In Human Welfare 1

Microbes#

Microbes are diverse–protozoa, bacteria, fungi and microscopic animal and plant viruses, viroids and also prions that are proteinacious infectious agents. Microbes are present everywhere – in soil, water, air, inside our bodies and that of other animals and plants. They are present even at sites where no other life-form could possibly exist–sites such as deep inside the geysers (thermal vents) where the temperature may be as high as 1000C, deep in the soil, under the layers of snow several metres thick, and in highly acidic environments. Microbes are diverse–protozoa, bacteria, fungi and microscopic animal and plant viruses, viroids and also prions that are proteinacious infectious agents.

Figure 1: Bacteria: (a) Rod-shaped, magnified 1500X; (b) Spherical shaped, magnified1500X; (c) A rodshaped bacterium showing flagella, magnified 50,000X

Viruses: (a) A bacteriophage; (b) Adenovirus which causes respiratory infections; (c) Rod-shaped Tobacco Mosaic Virus (TMV). Magnified about 1,00,000–1,50,000X

(a) Colonies of bacteria growing in a petri dish; (b) Fungal colony growing in a petri dish

Microbes in household products:#

1. Daily Use of Microbes:

• Microbes and their products are used in everyday life
• Common example: Production of curd from milk

2. Curd Production:

• Lactobacillus and lactic acid bacteria (LAB) convert milk to curd
• LAB produce acids that coagulate milk proteins
• Small amount of curd acts as starter/inoculum
• LAB multiply at suitable temperatures
• Improves nutritional quality by increasing vitamin B12
• LAB in stomach help check disease-causing microbes

3. Fermented Foods: a) Dosa and Idli:

• Dough fermented by bacteria
• CO2 production causes puffed-up appearance

b) Bread:

• Fermented using baker’s yeast (Saccharomyces cerevisiae)

4. Traditional Fermented Products:

• Toddy: Southern Indian drink from fermented palm sap
• Fermented fish
• Fermented soyabean
• Fermented bamboo shoots

5. Cheese Production:

• One of the oldest fermented food items
• Different varieties have unique characteristics:
  • Swiss cheese: Holes due to CO2 production by Propionibacterium sharmanii
  • Roquefort cheese: Ripened by specific fungi for distinct flavor

Microbes in industrial products:#

1. Fermented Beverages

• Yeasts (Saccharomyces cerevisiae) used to produce:
  • Wine
  • Beer
  • Whisky
  • Brandy
  • Rum
• Process varies based on:
  • Raw materials used
  • Processing method (with/without distillation)

2. Antibiotics

• First discovery: Penicillin by Alexander Fleming
• Discovered from Penicillium notatum mold
• Used extensively in World War II
• Nobel Prize (1945): Fleming, Chain, and Florey
• Treats diseases like:
  • Plague
  • Whooping cough
  • Diphtheria
  • Leprosy

3. Industrial Chemicals & Enzymes a) Organic Acids:

• Citric acid - Aspergillus niger
• Acetic acid - Acetobacter aceti
• Butyric acid - Clostridium butylicum
• Lactic acid - Lactobacillus

b) Enzymes:

• Lipases - Used in detergents
• Pectinases and proteases - Juice clarification
• Streptokinase - Blood clot removal

4. Bioactive Molecules:

• Cyclosporin A - Immunosuppressant (from Trichoderma polysporum)
• Statins - Cholesterol-lowering agent (from Monascus purpureus)

Microbes in sewage treatment:#

Introduction:

• Sewage is municipal waste-water containing human excreta
• Contains organic matter and pathogenic microbes
• Requires treatment before disposal into natural water bodies
• Treatment done by heterotrophic microbes naturally present in sewage

Treatment Stages:#

1. Primary Treatment:

• Physical removal of particles through filtration and sedimentation
• Removes floating debris through sequential filtration
• Grit (soil and pebbles) removed by sedimentation
• Forms primary sludge and effluent
• Effluent moves to secondary treatment

2. Secondary/Biological Treatment:

• Primary effluent passed into aeration tanks
• Mechanical agitation and air pumping
• Promotes growth of aerobic microbes (flocs)
• Microbes consume organic matter
• Reduces BOD (Biochemical Oxygen Demand)
• Bacterial flocs allowed to sediment
• Forms activated sludge

3. Further Processing:

• Part of activated sludge used as inoculum
• Remaining sludge goes to anaerobic digesters
• Anaerobic bacteria digest sludge
• Produces biogas (methane, hydrogen sulphide, CO2)
• Treated effluent released into natural water bodies

Current Challenges:

• Increasing urbanization producing more sewage
• Insufficient treatment plants
• Untreated sewage polluting rivers
• Government initiatives (Ganga/Yamuna Action Plans)
• Need for more treatment plants