Definitions [6]
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.
Definition: Zymology
Zymology is the applied science that deals with the biochemical processes of fermentation and their practical uses.
Definition: Oenology
Oenology is the science and study of wine and winemaking.
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: Microorganisms (Microbes) and Microbiology
- Microbes are found everywhere - in soil, water, air, and inside the bodies of humans, animals, and plants.
- They survive extreme conditions - thermal vents (100°C), deep soil, thick snow layers, and highly acidic environments.
- Types of microbes - protozoa, bacteria, fungi, microscopic plants, viruses, viroids, and prions (proteinaceous infectious agents).
- Bacteria and fungi grow on nutritive media to form visible colonies, essential for studying microorganisms.
- Microbes cause diseases in humans, animals, and plants, but many are also beneficial to human welfare.
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 Industries
- Microbes are cultured in large industrial fermenters to produce highly valuable secondary metabolites during their stationary growth phase.
- Specific strains of yeast are widely utilised in the commercial fermentation process to manufacture various alcoholic beverages from cereals and fruit juices.
- Industrial enzymes secreted by microbes serve practical daily purposes, such as clarifying bottled fruit juices and removing stubborn stains in laundry.
- Microorganisms are the primary source of life-saving medical treatments, producing essential antibiotics and critical bioactive molecules like immunosuppressants.
- Advanced biological techniques rely on microbes to commercially synthesise essential human proteins, dietary vitamins, and plant growth hormones.
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 chambers remove sand & stones.
- Primary Treatment - The sedimentation tank settles suspended solids and reduces coliform bacteria. Removes ~50–70% solids.
- Secondary Treatment - Aerobic bacteria decompose organic matter in aeration tanks, lowering BOD by 70–80%.
- Tertiary Treatment - Anaerobic bacteria digest sludge in sludge digesters; disinfection improves water quality.
- Chlorination kills any remaining pathogenic bacteria before water is released.
- Disposal - Treated water → natural water bodies; digested sludge → proper disposal/manure.
Key Points: Microbes in Production of Biogas
- Biogas is predominantly methane (CH₄), produced by microbial activity, and used for cooking and lighting.
- Methanogens (e.g., Methanobacterium) grow anaerobically on cellulosic material, producing CH₄, CO₂, and H₂S.
- Methanogens are found in anaerobic sludge and the rumen of cattle, helping to digest cellulose.
- Cattle dung (gobar) is rich in methanogens and is used to generate biogas, called gobar gas.
- A biogas plant has 4 parts: a concrete tank (digester), a floating cover, two outlets, and a gas holder.
- One outlet supplies biogas for cooking/lighting; the other removes spent slurry, which is used as fertiliser.
- Biogas technology in India was developed by IARI and KVIC.
Key Points: Microbes as Biocontrol Agents
- Meaning: Biocontrol agents are microbes that control pests by causing disease, competing with them, or killing them, thereby reducing dependence on chemical pesticides.
- Biopesticides: Safer, eco-friendly alternative to chemical pesticides. Key agents: Bacillus thuringiensis (Bt) → caterpillars, beetles; Beauveria bassiana → aphids, mites, whiteflies; 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. The most widely used bacterial biocontrol agent.
- Trichoderma: a fungus that acts as a biocontrol agent 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 fertilisers, 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-solubilising bacteria and fungi convert insoluble phosphates into forms available to plants.
- Biofertilisers improve crop yield, reduce fertiliser requirements, and help in sustainable agriculture and soil conservation.
