Chapter 10 : Microbes in Human Welfare

Besides macroscopic plants and animals, microbes are the major components of biological systems on this earth. Microbes are present everywhere in soil, water, air, inside our bodies and that of other animals and plants. Microbes are divers, they belongs to protozoa, bacteria, fungi, virus, viroids and prions. All microbes are not harmful, many microbes are useful to man in diverse ways. Some of the most important contributions of microbes to human welfare are discussed in this chapter.

Question 1: Describe the role of microbes in household products ?
The role of microbes in household products are:

  1. LAB(Lactic Acid Bacteria) and lactobacillus: Coagulates and partially digests the milk protein. Its importance:

    1. It converts milk into curd
    2. Increase nutritional quality by increasing vitamin-B12
    3. Check the disease causing microbes
  2. Toddy: Fermented sap from palms used as traditional drink in south India
  3. Dough: It is used for making dosa or idli and is fermented by bacteria or yeast(Saccharomyces cerevisiae)
  4. Swiss cheese: It have large holes due to production of large amount of co2 by bacterium Propionibacterium sharmanii
  5. Roquefort cheese: It is flavoured cheese produced by Penicillium roquefortii

Microbes In Industria Products

In industry, microbes are used to synthesise a number of products valuable to human beings. Beverages and antibiotics are some examples. Production on an industrial scale, requires growing microbes in very large vessels called fermentors.

Question 2: Write role of microbes in industrial fermentation ?
Fermented Beverages: Produced by Brewers yeast(Saccharomyces cerevisiae). The quality of fermented beverages depend on raw material(cereals, fruits) used and the processing done(with distillation- brandy, rum, whisky and without distillation- wine and beer)

Question 3: What are antibiotics ?
Antibiotics which are produce completely or partially by chemical synthesis, to stop the growth or destroy the micro-organisms. They are taken in low concentration. Ex- Penicillium, ofloxacin, erythromycin, ampilicin, amoxicillin, etc.

Question 4: Write chemical enzymes and other bioactive molecules ?
The chemical enzymes and other bioactive molecules are as follows: Microbes Types of microbes Product
1 Asperiligus niger fungus citric acid
2 Acetobacter aceti Bacteria Acetic acid
3 Clostridium butylicum Bacteria Butyric acid
4 Lactobacilius Bacteria Lactic acid
5 Streptococcus Bacteria Streptokinase
6 Trichoderma polysporum fungus Cyclosporin A
7 Monascus purpureus yeast Statin

functions of above products are: Product Function
1 Streptokinase It is used as clot buster to remove clots from the blood vessels from patients who have undergone myocardial infaction
2 Cyclosporin A It is used as immuno suppresive agent in organ transplant
3 Statin It is used as blood cholestrol lowering agent, it acts by competitively inhibiting enzyme responsible for synthesis of cholestrol
4 Lipase Are used in detergents because they are helpful in removing oily stains from laundry
5 Pectinase &protease Are used to breakdown pectins and protiens, these are present in the bottle fruit juices and also used to clearify the bottle of fruit juice

Sewage Treatment

A major component of urban wastewater is human excreta. This municipal wastewater is also called sewage. It contains large amounts of organic matter and microbes. Many of which are pathogenic. Before its disposal to the waterway, it is treated with primary and secondary treatment.

Sewage Treatment

Question 5: Differentiate between primary and secondary treatment ?
The difference between primary and secondary treatment is: Primary treatment Secondary treatment
1 It is a physical process It is a biochemical process
2 No decrease in BOD BOD decreases after treatment with aerobic bacteria
3 Sedementation and filtration are main process Digetion by aerobic and anerobic bacteria are the main processes
4 No bio gas and manure is produced Bio gas is formed due to anaerobic bacteria breakdown of organic waste and manure is formed 

Question 6: What is secondary treatment ?
It is a biological treatement:

  1. The primary effulent is passed into large aeriation tanks where aerobic microbes convert waste organic material into inorganic substances, thus decreases BOD
  2. When the BOD decreased, effulent is passed into settling tanks where bacterial flocs are allowed to sediment. This sediment is called activated sludge. A samll part of this sludge is used as inoculum in aeriation tanks.
  3. The major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters where anaerobic bacteria digest the waste and produced biogas(mixture of methane, H2S and CO2).

Benefits of secondary treatement:-

  1. Biogas formed which is used as fuel
  2. Remaining waste from anaerobic bacteria digesters is used as manure in fields.

Question 7: Explain the role of microbes in biogas production and its importance ?
Methanogens: These are bacteria which anaerobically breakdown cellulosic material to produce methane along with H2S and CO2(Ex: methanobacterium: they occur in the rumen of cattle, sheep, etc). Methanogens have the following importance:-

  1. Methanogens convert animal waste and plant waste into methane gas which is inflammable gas and used as a clean fuel.
  2. The waste left is used as manure which increases the soil fertility for the crop production.

Question 8: Explain the structure of biogas plant?
Biogas plant consists of a concrete tank(10-15 feet deep) in which bio waste are collected and a slurry of dung is fed. A floating cover is placed over the sluury which keeps on rising as the gas is produced in the tank due to the microbial activity. The biogas plant has an outlet, which is connected to a pipe to supply biogas.
Question 9: Explain the role of microbes as biocontrol agents ?
Biological control involves use of organisms to control pests or insects. These are target specific and do not harm other plants and animals. Following are the examples of biological control agents:

  1. Beetle with red and black marking: The ladybird and dragonflies are used to get rid of aphids and mosquitoes.
  2. fungus Trichoderma: These are free living fungi which is used as biocontrol agents of several plant pathogens.
  3. Baculovirus: These are pathogens that attack insects and other arthropods, baculovirus used as biolgical control agents in the genus Nucleopolyhedrovirus.
  4. Bacilius thuringinesis bacteria: It kill the caterpillar which feeds on Brassica, fruit trees, etc.

Question 10: Who were the scientists who discovered antibiotics Penicilin? Answer:Alexander Fleming, Ernst Chain and Howard Florey got nobel prize for discovery of antibiotics Penicilin. Penicilin is the first antibiotics obatained from fungiPenicilin notatum by Alexander when he was working with Staphylococci bacteria.
Question 11: Explain the role of microbes as bio-fertilisers?
Bio-fertilisers: Those organisms which provide nitrogen and phosphorus nutrient and also enrich quality of the soil. Example:

  • Bacteria(free living): Azospirilum and azotobacter
  • Bacteria(Symbiotic): Rhizobium
  • Fungi: Mycorizha: is an association between fungi and roots of higher plants(genus: glomus). Fungi increases surface area of roots for absorption of the water and minerals. Fungi provides inorganic nutrients to plant and plant gives organic food to fungi.
  • Cynobacteria: It is a blue green algae and they are biofertilisers and acn fix atmospheric nitrogen and provide them to plants, Ex: Anabena, nostoc and oscillatoria.

Biogas and Biogas Plant

Biogas is a mixture of methane (CH4) and carbon dioxide (CO2) produced anaerobically during a two stage bacterial breakdown of organic material. The excreta (dung) of cattle, commonly called gobar, is rich in these bacteria. Dung can be used for generation of biogas. Biogas production takes place in biogas plant.

Biogas plant

Dharmendra Gaur

Dharmendra Gaur (Msc. Zoology) aka DRGP. I love to learn and teach biology. By this blog I want to increase my knowledge and share my knowledge with others. Feel free to ask what ever you want to ask related to biology, I try my best to help you.

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