$\displaystyle \small \bullet$ Microbes are the major components of biological systems on this earth.
$\displaystyle \small \bullet$ Microbes are present everywhere - in soil, water, air, inside the body of plants and animals, inside thermal vents, deep in the soil, under the layers of snow several meters thick and in highly acidic environments.
$\displaystyle \small \bullet$ Microbes could be of various types like bacteria, protozoans, fungi, microscopic plants, viruses, viroids and prions.
$\displaystyle \small \bullet$ Though a large number of them cause disease in plants and animals including humans, all microbes are not harmful. a number of microbes are very useful, particularly in industries, agriculture and medicine.
MICROBES IN HOUSEHOLD PRODUCTS
1. Production of curd
$\displaystyle \small \bullet$ Milk is converted to curd by micro-organisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) which grow in milk and convert it to curd.
$\displaystyle \small\bullet$ During growth of bacteria, the LAB produce acids that coagulate and partially digest the milk proteins.
$\displaystyle \small \bullet$ A small amount of curd added to the fresh milk as inoculum or starter which at suitable temperatures multiply, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin $\displaystyle \small B_{12}$.
$\displaystyle \small \bullet$ In our stomach, the LAB play very beneficial role in checking disease causing microbes.
2. Fermentation
$\displaystyle \small \bullet$ The dough, which is used for making foods such as dosa and idli is also fermented by bacteria.
$\displaystyle \small \bullet$ The puffed-up appearance of dough is due to the production of $\displaystyle \small CO_{2}$.
$\displaystyle \small \bullet$ The dough, which is used for making bread, is fermented using baker’s yeast (Saccharomyces cerevisiae).
$\displaystyle \small \bullet$ A number of traditional drinks and foods are also made by fermentation by the microbes.
$\displaystyle \small \bullet$ Toddy, a traditional drink of some parts of southern India is made by fermenting sap from palms.
$\displaystyle \small \bullet$ Microbes are also used to ferment fish, soya bean and bamboo shoots to make foods.
3. Production of cheese
$\displaystyle \small \bullet$ Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.
$\displaystyle \small \bullet$ The large holes in ‘Swiss cheese’ are due to production of a large amount of $\displaystyle \small CO_{2}$ by a bacterium named Propionibacterium sharmanii.
$\displaystyle \small \bullet$ The ‘Roquefort cheese’ are ripened by growing a specific fungi on them, which gives them a particular flavour.
MICROBES IN INDUSTRIAL PRODUCTS
A number of products like beverages and antibiotics involve uses of microbes. Production on large scale requires growing microbes in very large vessels called fermenters.
1. Fermented Beverages
$\displaystyle \small \bullet$ Microbes are used for the production of beverages like wine, beer, whiskey, brandy or rum.
$\displaystyle \small \bullet$ Saccharomyces cerevisiae, is used for the production of fermented beverages.
$\displaystyle \small \bullet$ Malted cereals and fruit juices are fermented by S. cerevisiae to produce ethanol.
$\displaystyle \small \bullet$ Wine and beer are produced without distillation.
$\displaystyle \small \bullet$ Whisky, brandy and rum are produced by distillation of the fermented broth
2. Antibiotics
$\displaystyle \small \bullet$ Antibiotics are the chemical substances which are produced by some microbes and can kill or stop the growth the growth of other microbes.
$\displaystyle \small \bullet$ Alexander Flemming discovered penicillin obtained from Penicillium notatum which was the first antibiotic to be discovered.
$\displaystyle \small \bullet$ Alexander Fleming while working on Staphylococci bacteria observed a mould growing in one of his unwashed culture plates around which Staphylococci could not grow and he found out that it was due to a chemical produced by Penicillium notatum.
$\displaystyle \small \bullet$ Its full potential as an effective antibiotic was established much later by Ernest Chain and Howard Florey. This antibiotic was extensively used to treat American soldiers wounded in World War II. Fleming, Chain and Florey were awarded the Nobel Prize in 1945, for this discovery.
$\displaystyle \small \bullet$ Antibiotics are used against the deadly diseases like plague, whooping cough, leprosy, malaria etc
3. Chemicals, enzymes and other bioactive molecules
Microbes are used for the production of organic acids, alcohols and enzymes.
Chemicals produced by the microbes are:
1. Aspergillus niger (a fungus) is the producer of citric acid.
2. Acetobacter aceti (a bacterium) produces acetic acid.
3. Clostridium butylicum (a bacterium) is the producer of butyric acid
4. Yeast (Saccharomyces cerevisiae) is used for commercial production of ethanol.
5. Lactobacillus (a bacterium) is the producer of lactic acid.
Enzymes produced by the microbes are:
1. Lipases: used in detergent formulations.
2. Pectinases and proteases: used in making bottled fruit juices clearer.
3. Streptokinase: produced by the bacterium Streptococcus is used as a ‘clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infraction leading to heart attack.
Bioactive molecules produced by microbes are:
1. Cyclosporin A: used as an immunosuppressive agent in organ-transplant patients, is produced by the fungus Trichoderma polysporum.
2. Statins: produced by the yeast Monascus purpureus is used as blood-cholesterol lowering agents which acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol.
MICROBES IN SEWAGE TREATMENT
$\displaystyle \small \bullet$ Municipal waste water contains large amount of organic matter and microbes is called sewage. Sewage is pathogenic and cannot be discharged into natural water bodies like rivers and streams. Sewage is treated in sewage treatment plant to make it less polluting by using heterotrophic microbes naturally present in sewage.
$\displaystyle \small \bullet$ Sewage treatment is carried out in two stages.
1. Primary treatment
$\displaystyle \small \circ$ These treatment steps basically involve physical removal of large and small particles.
$\displaystyle \small \circ$ Initially, floating debris is removed by sequential filtration and then the grit are removed by sedimentation.
$\displaystyle \small \circ$ All solids that settle form the primary sludge, and the supernatant forms the effluent.
$\displaystyle \small \circ$ The effluent from the primary settling tank is taken for secondary treatment.
2. Secondary treatment or biological treatment
$\displaystyle \small \circ$ The primary effluent is passed into large aeration tanks where it is constantly agitated which allows vigorous growth of useful aerobic microbes into flocs.
$\displaystyle \small \circ$ Flocs are the masses of bacteria associated with fungal filaments to form mesh like structures.
$\displaystyle \small \circ$ While growing, the microbes significantly reduces the BOD (biochemical oxygen demand) which is the amount of oxygen required to oxidize total organic matter in the effluent.
$\displaystyle \small \circ$ The BOD test measures the rate of uptake of oxygen by micro-organisms, the greater the BOD of waste water, more is its polluting potential.
$\displaystyle \small \circ$ The effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment and the sediment is called activated sludge .
$\displaystyle \small \circ$ A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum.
$\displaystyle \small \circ$ The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters where other kinds of bacteria grow anaerobically which digest the bacteria and the fungi in the sludge.
$\displaystyle \small \circ$ During digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide which form biogas.
$\displaystyle \small \circ$ The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams.
$\displaystyle \small \bullet$ Microbes play a major role in treating millions of gallons of waste water everyday across the globe. This methodology has been practiced for more than a century now, in almost all parts of the world. Till date, no manmade technology has been able to rival the microbial treatment of sewage.
$\displaystyle \small \bullet$ Due to increasing urbanization, sewage is being produced in much larger quantities than ever before. However the number of sewage treatment plants has not increased enough to treat such large quantities. So the untreated sewage is often discharged directly into rivers leading to their pollution and increase in water-borne diseases.
$\displaystyle \small \bullet$ The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna Action Plan to save these major rivers of our country from pollution. Under these plans, it is proposed to build a large number of sewage treatment plants so that only treated sewage may be discharged in the rivers.
$\displaystyle \small \bullet$ Microbes are present everywhere - in soil, water, air, inside the body of plants and animals, inside thermal vents, deep in the soil, under the layers of snow several meters thick and in highly acidic environments.
$\displaystyle \small \bullet$ Microbes could be of various types like bacteria, protozoans, fungi, microscopic plants, viruses, viroids and prions.
$\displaystyle \small \bullet$ Though a large number of them cause disease in plants and animals including humans, all microbes are not harmful. a number of microbes are very useful, particularly in industries, agriculture and medicine.
MICROBES IN HOUSEHOLD PRODUCTS
1. Production of curd
$\displaystyle \small \bullet$ Milk is converted to curd by micro-organisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) which grow in milk and convert it to curd.
$\displaystyle \small\bullet$ During growth of bacteria, the LAB produce acids that coagulate and partially digest the milk proteins.
$\displaystyle \small \bullet$ A small amount of curd added to the fresh milk as inoculum or starter which at suitable temperatures multiply, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin $\displaystyle \small B_{12}$.
$\displaystyle \small \bullet$ In our stomach, the LAB play very beneficial role in checking disease causing microbes.
2. Fermentation
$\displaystyle \small \bullet$ The dough, which is used for making foods such as dosa and idli is also fermented by bacteria.
$\displaystyle \small \bullet$ The puffed-up appearance of dough is due to the production of $\displaystyle \small CO_{2}$.
$\displaystyle \small \bullet$ The dough, which is used for making bread, is fermented using baker’s yeast (Saccharomyces cerevisiae).
$\displaystyle \small \bullet$ A number of traditional drinks and foods are also made by fermentation by the microbes.
$\displaystyle \small \bullet$ Toddy, a traditional drink of some parts of southern India is made by fermenting sap from palms.
$\displaystyle \small \bullet$ Microbes are also used to ferment fish, soya bean and bamboo shoots to make foods.
3. Production of cheese
$\displaystyle \small \bullet$ Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.
$\displaystyle \small \bullet$ The large holes in ‘Swiss cheese’ are due to production of a large amount of $\displaystyle \small CO_{2}$ by a bacterium named Propionibacterium sharmanii.
$\displaystyle \small \bullet$ The ‘Roquefort cheese’ are ripened by growing a specific fungi on them, which gives them a particular flavour.
MICROBES IN INDUSTRIAL PRODUCTS
A number of products like beverages and antibiotics involve uses of microbes. Production on large scale requires growing microbes in very large vessels called fermenters.
1. Fermented Beverages
$\displaystyle \small \bullet$ Microbes are used for the production of beverages like wine, beer, whiskey, brandy or rum.
$\displaystyle \small \bullet$ Saccharomyces cerevisiae, is used for the production of fermented beverages.
$\displaystyle \small \bullet$ Malted cereals and fruit juices are fermented by S. cerevisiae to produce ethanol.
$\displaystyle \small \bullet$ Wine and beer are produced without distillation.
$\displaystyle \small \bullet$ Whisky, brandy and rum are produced by distillation of the fermented broth
2. Antibiotics
$\displaystyle \small \bullet$ Antibiotics are the chemical substances which are produced by some microbes and can kill or stop the growth the growth of other microbes.
$\displaystyle \small \bullet$ Alexander Flemming discovered penicillin obtained from Penicillium notatum which was the first antibiotic to be discovered.
$\displaystyle \small \bullet$ Alexander Fleming while working on Staphylococci bacteria observed a mould growing in one of his unwashed culture plates around which Staphylococci could not grow and he found out that it was due to a chemical produced by Penicillium notatum.
$\displaystyle \small \bullet$ Its full potential as an effective antibiotic was established much later by Ernest Chain and Howard Florey. This antibiotic was extensively used to treat American soldiers wounded in World War II. Fleming, Chain and Florey were awarded the Nobel Prize in 1945, for this discovery.
$\displaystyle \small \bullet$ Antibiotics are used against the deadly diseases like plague, whooping cough, leprosy, malaria etc
3. Chemicals, enzymes and other bioactive molecules
Microbes are used for the production of organic acids, alcohols and enzymes.
Chemicals produced by the microbes are:
1. Aspergillus niger (a fungus) is the producer of citric acid.
2. Acetobacter aceti (a bacterium) produces acetic acid.
3. Clostridium butylicum (a bacterium) is the producer of butyric acid
4. Yeast (Saccharomyces cerevisiae) is used for commercial production of ethanol.
5. Lactobacillus (a bacterium) is the producer of lactic acid.
Enzymes produced by the microbes are:
1. Lipases: used in detergent formulations.
2. Pectinases and proteases: used in making bottled fruit juices clearer.
3. Streptokinase: produced by the bacterium Streptococcus is used as a ‘clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infraction leading to heart attack.
Bioactive molecules produced by microbes are:
1. Cyclosporin A: used as an immunosuppressive agent in organ-transplant patients, is produced by the fungus Trichoderma polysporum.
2. Statins: produced by the yeast Monascus purpureus is used as blood-cholesterol lowering agents which acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol.
MICROBES IN SEWAGE TREATMENT
$\displaystyle \small \bullet$ Municipal waste water contains large amount of organic matter and microbes is called sewage. Sewage is pathogenic and cannot be discharged into natural water bodies like rivers and streams. Sewage is treated in sewage treatment plant to make it less polluting by using heterotrophic microbes naturally present in sewage.
$\displaystyle \small \bullet$ Sewage treatment is carried out in two stages.
1. Primary treatment
$\displaystyle \small \circ$ These treatment steps basically involve physical removal of large and small particles.
$\displaystyle \small \circ$ Initially, floating debris is removed by sequential filtration and then the grit are removed by sedimentation.
$\displaystyle \small \circ$ All solids that settle form the primary sludge, and the supernatant forms the effluent.
$\displaystyle \small \circ$ The effluent from the primary settling tank is taken for secondary treatment.
2. Secondary treatment or biological treatment
$\displaystyle \small \circ$ The primary effluent is passed into large aeration tanks where it is constantly agitated which allows vigorous growth of useful aerobic microbes into flocs.
$\displaystyle \small \circ$ Flocs are the masses of bacteria associated with fungal filaments to form mesh like structures.
$\displaystyle \small \circ$ While growing, the microbes significantly reduces the BOD (biochemical oxygen demand) which is the amount of oxygen required to oxidize total organic matter in the effluent.
$\displaystyle \small \circ$ The BOD test measures the rate of uptake of oxygen by micro-organisms, the greater the BOD of waste water, more is its polluting potential.
$\displaystyle \small \circ$ The effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment and the sediment is called activated sludge .
$\displaystyle \small \circ$ A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum.
$\displaystyle \small \circ$ The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters where other kinds of bacteria grow anaerobically which digest the bacteria and the fungi in the sludge.
$\displaystyle \small \circ$ During digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide which form biogas.
$\displaystyle \small \circ$ The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams.
$\displaystyle \small \bullet$ Microbes play a major role in treating millions of gallons of waste water everyday across the globe. This methodology has been practiced for more than a century now, in almost all parts of the world. Till date, no manmade technology has been able to rival the microbial treatment of sewage.
$\displaystyle \small \bullet$ Due to increasing urbanization, sewage is being produced in much larger quantities than ever before. However the number of sewage treatment plants has not increased enough to treat such large quantities. So the untreated sewage is often discharged directly into rivers leading to their pollution and increase in water-borne diseases.
$\displaystyle \small \bullet$ The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna Action Plan to save these major rivers of our country from pollution. Under these plans, it is proposed to build a large number of sewage treatment plants so that only treated sewage may be discharged in the rivers.
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