Chapter 7 – Introduction to Microbiology
1. Rewrite the following statements using the correct of the options and explain the completed statements.
(gluconic acid, coagulation, amino acid, acetic acid, clostridium, lactobacilli)
a. Process of ______ of milk proteins occurs due to lactic acid.
Ans: coagulation
b. Harmful bacteria in like ______ in the intestine are destroyed due to probiotics.
Ans: clostridium
c. Chemically, vinegar is ______.
Ans: acetic acid
d. Salts which can be used as supplement of calcium and iron are obtained from ______ acid.
Ans: gluconic acid
2. Match the pairs
| ‘A’ group | ‘B’ group |
|---|---|
a. Xylitol | 1. Pigment |
b. Citric acid | 2. To impart sweetness |
c. Lycopene | 3. Microbial restrictor |
d. Nycin | 4. Protein binding emulsifier |
5. To impart acidity |
Ans:
| ‘A’ group | ‘B’ group |
|---|---|
a. Xylitol | 2. To impart sweetness |
b. Citric acid | 5. To impart acidity |
c. Lycopene | 1. Pigment |
d. Nycin | 3. Microbial restrictor |
3. Answer the following.
a. Which fuels can be obtained by microbial processes? Why is it necessary to increase the use of such fuels?
Ans:
(i) Various fuels like methane, ethanol, hydrogen gas, etc. are fuels obtained by microbial processes.
(ii) It is necessary to increase the usage of such fuels so as to reduce exhaustion of fossil fuel resources.
(iii) Most of these fuels can be obtained by anaerobic decomposition of waste products such as domestic waste, agricultural waste, etc. Hence, their cost of production is relatively very high.
(iv) When methane is burned, comparatively lower amounts of smog forming pollutants, toxic air and gases are generated.
(v) Ethanol is a clean fuel. It is obtained during fermentation of molasses by Saccharomyces.
(vi) Hydrogen gas is considered as the fuel of the future since it does not emit any harmful substances on burning and is produced by bio-photolysis of water.
(vii) As a result, it is necessary to increase the use of fuels obtained by microbial processes.
Types:
(i) Ethanol-biologically produced alcohols, most commonly ethanol and less commonly propanol and butanol are produced by the action of microorganisms and enzymes through the fermentation of sugar or starch cellulose.
(ii) Bibutanol, also called biogasoline, is often claimed to provide a direct replacement for gasoline. Biogas is methane produced by the process of anaerobic digestion of organic material by anaerobes.
b. How can the oil spills of rivers and oceans be cleaned?
Ans:
(i) Bacteria like Pseudomonas spp. and Alcanivorax borkumensis have the ability to destroy the pyridines and other chemicals.
(ii) Hence, these bacteria are used to clear the oil spills.
(iii) These are called Hydrocarbonoclastic bacteria (HCB).
(iv) HCB decomposes the hydrocarbons and brings about the reaction of carbon with oxygen. CO₂ and water is formed in the process.
c. How can the soil polluted by acid rain be made fertile again?
Ans:
(i) Sulphuric acid is present in the acid rain and in materials coming out of mines.
(ii) Erosion of bridges, metal statues, occurs due to acid rain.
(iii) Sulphuric acid is the source of energy for some species of bacteria like Acidophilum spp. and Acidobacillus ferrooxidans.
(iv) Hence, these bacteria can control the soil pollution occurring due to acid rain, and the soil can be made fertile again.
d. Explain the importance of bio-pesticides in organic farming.
Ans:
(i) Fluoroacetamide-like chemicals are mixed with soil due to use of chemical pesticides in agriculture.
(ii) These prove to be harmful to other plants and animals as well as cause skin disease to humans. Therefore biopesticides are used nowadays.
(iii) Bacterial and fungal toxins which can destroy pests and pathogens can be directly integrated into plants with the help of biotechnology.
(iv) Being toxic to insects, plants are saved from them.
(v) Spinosad, is a biopesticide. It is a by-product of fermentation.
e. Which are the reasons for increasing the popularity of probiotic products?
Ans:
(i) Probiotics are milk products containing active bacteria.
(ii) These microbes maintain the balance of intestinal organisms.
(iii) These products form the colonies of useful microbes in the alimentary canal and control other microbes and their metabolic activities, improve resistance and lower the effects of harmful substances formed during metabolic activities.
(iv) Useful microbes become inactive due to antibiotics, probiotics make them active again.
(v) Nowadays, probiotics are used for treatment of diarrhoea and treatment of poultry also.
f. How the bread and other products produced using baker’s yeast are nutritious?
Ans:
(i) Compressed yeast is used in the commercial bakery industry.
(ii) It is available in dry, granular form for domestic use.
(iii) Yeast produced for commercial use contains various useful contents like carbohydrates, fats, proteins, various vitamins and minerals.
(iv) Due to this, bread and other products produced with the help of yeast become nutritive.
g. Which precautions are necessary for proper decomposition of domestic waste?
Ans:
(i) Segregation of waste – waste has to be segregated into dry and wet and accordingly headed for disposal.
(ii) Dry wastes need to be sent for recycling.
(iii) Wet wastes need to be sent to land-filling sites for composting.
h. Why is it necessary to ban the use of plastic bags?
Ans:
(i) Plastic bags pollute our land and water resources.
(ii) Plastic bags do not degrade easily.
(iii) Plastic bags are harmful to wildlife, marine and human health.
(iv) Hence, plastic bags should be banned.
4. Complete the following conceptual picture.
Ans:
5. Give scientific reasons.
a. Use of mutant strains has been increased in industrial microbiology.
Ans:
(i) Use of microbes to obtain a product which is cheaper is now a trend in industrial Microbiology. Mutant strains are genetically improved strains which give higher yields and therefore decrease the cost of the products.
(ii) Mutant strains are formed by alterations of nucleotides in the DNA of microorganisms to suit the needs of the industry.
(iii) Mutant strains are used for producing virus resistant bacterial strains are used in Dairy industry (milk products) so as to avoid the unwanted bacteria and viruses attacking and out membering the original ones.
(iv) In the alcohol industry mutant strains improve the flavour and quality of wine or beer.
b. Enzymes obtained by microbial process are mixed with detergents.
Ans:
(i) When detergents are mixed with microbial enzymes, they start working more efficiently.
(ii) The cleaning process takes place at lesser temperatures.
(iii) Therefore, for better results, enzymes obtained by microbial processes are mixed with detergents.
c. Microbial enzymes are used instead of chemical catalysts in chemical industry.
Ans:
(i) Microbial enzymes are active at low temperature, pH and pressure, due to which energy is saved and erosion – proof instruments are also not necessary.
(ii) Enzymes carry out specific processes, hence unnecessary by-products are not formed due to which expenses on purification are minimized.
(iii) Elimination and decomposition of waste materials is avoided and enzymes can be reused. Such enzymes are eco-friendly.
(iv) Therefore microbial enzymes are used instead of chemical catalysts in the chemical industry.
6. Complete the following conceptual picture with respect to uses.
Ans:
7. Complete the following conceptual picture related to environmental management.
Ans:
8. Answer the following.
a. What is role of microbes in compost production?
Ans: All biodegradable waste can be converted into compost.
(i) Bacteria, fungi and actinomycetes are the microbes that decompose the organic matter.
(ii) Aerobic bacteria are the most important ones.
(iii) Microbes break down the organic matter and produce carbon dioxide, water, heat and humus which makes it very nutritious.
(iv) They provide the most rapid and effective composting.
(v) Their excreta contains plant nutrients such as nitrogen, phosphorus and magnesium.
(vi) Actinomycetes are responsible for the earthy smell of the compost.
(vii) They decompose cellulose, starches and proteins liberating carbon, nitrogen and ammonia in the process, which are useful for higher plants.
(viii) Fungi breakdown cellulose and lignin and take over the final stage of composting.
(ix) Thus microbes help in recycling the nutrients through composting.
b. What are the benefits of mixing ethanol with petrol and diesel?
Ans:
(i) Ethanol is a renewable, domestically produced transportation fuel.
(ii) It burns more cleanly, producing less carbon emission.
(iii) Reduces dependence on fossil fuels.
(iv) Enhances the octane content in the fuel.
c. Which plants are cultivated to obtain the fuel?
Ans:
(i) Crops cultivated to obtain fuel are corn,
sugarcane, wheat, soya beans, beet, Jatropha, etc.
(ii) These are the main sources for the most common types of biofuels today.
d. Which fuels are obtained from biomass?
Ans: Fuels obtained from biomass:
(i) Solid fuels : Coal, dung, crop residue
(ii) Liquid fuels : Vegetable oils, alcohol
(iii) Gaseous fuels: Gobar gas, coal gas.
e. How does the bread become spongy?
Ans:
(i) Different types of bread are produced from cereal flour.
(ii) Dough for bread is formed by mixing baker’s yeast – Saccharomyces cerevisiae, water, salt and other necessary materials with flour.
(iii) Due to fermentation of carbohydrates by yeast, sugar is converted into carbon-dioxide (CO₂) and ethanol (C₂H₅OH).
(iv) Dough rises up due to CO₂ and the bread becomes spongy.