Definitions [4]
Define the following term
Zymology
Zymology is an applied science which deals with the biochemical process of fermentation and its practical uses.
Define the following term
Antibiotics
Antibiotics are chemical substances produced by microorganisms which can kill or retard the growth of other disease causing microbes even in low concentration. Antibiotic means “against life”.
Define the following terms
Superbug
"Superbug" is a term used to describe strains of bacteria that are resistant to the majority of antibiotics commonly used today.
Define bioherbicides.
Bioherbicides are living creatures such as microbes, fungi, insects, or other pathogens that are employed to restrict the population of undesired plants in agricultural fields, ponds, lakes, and so on.
Key Points
Key Points: Microbes in Household Products
| Product | Micro-organisms Used | Function |
|---|---|---|
| Curd | Lactobacillus (LAB) | Converts milk into curd, increases vitamin B₁₂ |
| Butter | Streptococcus cremoris, Leuconostoc dextranicum | Gives flavour and aroma |
| Yogurt | Lactobacillus bulgaricus, Streptococcus thermophilus | Ferments milk at 40°C |
| Cheese | Streptococcus lactis, Leuconostoc, fungi | Curdling and ripening of cheese |
| Swiss Cheese | Propionibacterium shermanii | Produces CO₂, forms holes |
| Roquefort Cheese | Penicillium roqueforti | Ripening and flavour |
| Camembert Cheese | Penicillium camemberti | Soft texture and taste |
Key Points: Microbes in Food Production
| Food Item | Micro-organism Used | Role |
|---|---|---|
| Dosa / Idli | Bacteria | Fermentation produces CO₂, dough rises |
| Bread | Saccharomyces cerevisiae | CO₂ production, leavening |
| Sausages | Lactic acid bacteria | Meat fermentation |
| Sauerkraut | Enterobacter, Leuconostoc, Lactobacillus | Cabbage fermentation |
| Soy sauce | Aspergillus oryzae | Fermentation of soybeans |
| Tempeh | Rhizopus species | Fermented soybean food |
| Tofu / Sofu | Mucor species | Cheese-like product |
| Toddy | Yeast | Fermentation of palm sap |
Key Points: Microbes in Industries
- Bio-active Compounds — Streptokinase (Streptococcus) = clot buster; Statins (Monascus purpureus) = lowers blood cholesterol.
- Antibiotics — Penicillin (Penicillium chrysogenum), Streptomycin (S. griseus), Erythromycin (S. erythreus), Oxytetracycline (S. aurifaciens), Bacitracin (Bacillus licheniformis).
- Alcoholic Beverages — Yeast (Saccharomyces cerevisiae) ferments cereals/fruit juices. Distilled = Whisky, Brandy, Rum; Non-distilled = Wine, Beer. Fenny = Goa's cashew wine.
- Organic Acids — Citric & Gluconic acid (Aspergillus niger), Acetic acid/vinegar (Acetobacter aceti), Fumaric acid (Rhizopus arrhizus).
- Vitamins — B₂ (Neurospora gossypii), B₁₂ (Pseudomonas denitrificans), Vitamin C (Aspergillus niger).
- Industrial Enzymes — Invertase (S. cerevisiae), Lipase (Candida lipolytica), Cellulase (Trichoderma konigii), Pectinase (Aspergillus niger).
- Gibberellins — Isolated from fungus Gibberella fujikuroi; ~15 types; used for parthenocarpy, seed dormancy breaking, flowering induction & enlarging grape fruits.
Key Points: Microbes in Sewage Treatment
- Sewage = 99.5–99.9% water + 0.1–0.5% organic/inorganic matter + microbes (bacteria, viruses, fungi, algae, etc.)
- Preliminary Treatment — Bar screens remove large solids; Grit Chamber removes sand & stones.
- Primary Treatment — Sedimentation tank settles suspended solids; reduces coliform bacteria. Removes ~50–70% solids.
- Secondary Treatment — Aerobic bacteria decompose organic matter in aeration tanks; lowers BOD by 70–80%.
- Tertiary Treatment — Anaerobic bacteria digest sludge in sludge digesters; disinfection improves water quality.
- Chlorination — Kills remaining pathogenic bacteria before water release.
- Disposal — Treated water → natural water bodies; digested sludge → proper disposal/manure.
Key Points: Microbes in Sewage Treatment
- Sewage treatment is carried out in two stages: primary treatment and secondary (biological) treatment.
- Primary treatment involves physical removal of floating debris by filtration and heavy particles by sedimentation, forming primary sludge and effluent.
- In secondary treatment, the effluent is aerated in large tanks to promote growth of aerobic microbes that consume organic matter.
- Microbial activity reduces the BOD (Biochemical Oxygen Demand), thereby decreasing the polluting potential of sewage.
- The settled activated sludge is digested anaerobically to produce biogas, and the treated effluent is released into natural water bodies.
Key Points: Ganga and Yamuna River Pollution Control Initiatives
| Aspect | Ganga Action Plan | Yamuna Action Plan |
|---|---|---|
| Reason | To control pollution due to untreated sewage and waste | To reduce pollution caused by sewage discharge |
| River | River Ganga | River Yamuna |
| Length / Area | About 2,500 km (Gangotri to Bay of Bengal) | States of U.P., Delhi, and Haryana |
| Launched | 1986 | April 1993 |
| Launched by | Late Prime Minister Rajiv Gandhi | Government of India |
| Main Objective | Improve water quality of river Ganga | Control pollution of river Yamuna |
| Key Measures | Sewage interception, diversion, treatment plants | Construction of sewage treatment plants |
| Recent Initiative | Namami Gange Project | Continued under Yamuna Action Plan |
Key Points: Microbes in Energy Generation
- Meaning — Biogas is a renewable energy source obtained through microbial fermentation. Key microbes: Archaebacteria and Bacillus.
- Composition — Mixture of CH₄, CO₂, H₂S, H₂, and N₂. Methane is the main combustible gas.
- Substrate & Plant — Cattle dung is the common raw material. Plant has Digester and Gas Holder. Developed by KVIC and IARI in India.
- Stage I – Solubilisation — Hydrolytic bacteria break down proteins, fats, and cellulose into simpler soluble compounds.
- Stage II – Acidogenesis — Fermentative bacteria convert monomers into organic acids (e.g., acetic acid), H₂ and CO₂.
- Stage III – Methanogenesis — Methanosarcina, Methanobacterium convert acetate + H₂ + CO₂ into methane (biogas).
Key Points: Types of Biocontrol Agents
| Category | Biocontrol Agent | Target / Use |
|---|---|---|
| Insects | Ladybird beetle | Controls aphids |
| Insects | Dragonfly | Controls mosquitoes |
| Viruses | Baculoviruses (NPV) | Control insect pests like bollworm |
| Bacteria | Bacillus thuringiensis | Controls insect pests and mosquito larvae |
| Bacteria | Agrobacterium radiobacter (K-84) | Controls crown gall disease |
| Bacteria | Pseudomonas sp. | Controls fungal disease (damping off) |
| Fungi | Trichoderma sp. | Controls many plant diseases |
| Fungi | Beauveria, Metarhizium, Verticillium | Control insect pests |
| Fungi | Aschersonia aleyrodis | Controls whiteflies |
Key Points: Microbes as Biocontrol Agents
- Meaning — Biocontrol agents are microbes that control pests by causing disease, competing with, or killing them, reducing dependence on chemical pesticides.
- Biopesticides — Safer, eco-friendly alternative to chemical pesticides. Key agents: Bacillus thuringiensis (Bt) → caterpillars, beetles; Beauveria bassiana → aphids, mites, white flies; Nosema locustae (protozoa) → grasshoppers, crickets; NPV & Granulovirus → gypsy moths, ants, wasps.
- Bacillus thuringiensis (Bt) — Dried spores mixed with water and sprayed on plants to kill butterfly caterpillars. Most widely used bacterial biocontrol agent.
- Trichoderma — A fungus that acts as a biocontrol agent specifically against soil-borne fungal plant pathogens.
- Microbial Herbicides — Phytophthora palmivora → milkweed; Alternaria crassa → water hyacinth; Fusarium spp. → most weeds; Pseudomonas, Xanthomonas, Agrobacterium → several weeds.
- Insects as Herbicides — Tyria moth controls Senecio jacobeae weed; Cactoblastis cactorum controls cacti weeds.
Key Points: Microbes as Biofertilizers
- Biofertilizers are living micro-organisms that improve soil fertility by increasing the availability of nutrients to plants.
- They are eco-friendly alternatives to chemical fertilizers, which degrade soil quality and reduce microbial life.
- Nitrogen-fixing microbes such as Rhizobium, Azotobacter, Azospirillum, and Frankia convert atmospheric nitrogen into usable forms.
- Legume–Rhizobium symbiosis forms root nodules that fix large amounts of nitrogen and enrich the soil for subsequent crops.
- Azolla–Anabaena symbiosis and cyanobacteria are widely used in paddy fields and significantly increase rice yield.
- Mycorrhiza (fungus–root association) enhances absorption of phosphorus and other minerals and protects plants from pathogens.
- Phosphate-solubilizing bacteria and fungi convert insoluble phosphates into forms available to plants.
- Biofertilizers improve crop yield, reduce fertilizer requirement, and help in sustainable agriculture and soil conservation.
Important Questions [10]
- Home-made fruit juices are turbid, while the bottled ,fruit juices purchased from the market are clear. Give a reason for this difference.
- Give the biological name of the following: The microbe used to produce Swiss cheese.
- Give the biological name of the following: A symbiotic nitrogen-fixing bacterium found in root nodules.
- Which one of the following factors is responsible for activation of protoxin into active Bt toxin of Bacillus thuringiensis?
- Expand DDT
- Give the biological name of the following: The mould from which penicillin is obtained.
- Give the biological name of the following: The microbe used to control insect larvae growing on cotton.
- Give the biological name of the following: The fungus that is being developed as a bio-control agent.
- Give Reasons for the Following: Nitrogenous Fertilizers Are Not Applied in Fields Where Leguminous Crops Grow.
- Why are the spores of Bacillus thuringiensis used as bioinsecticide?
