.Big holes in Swiss cheese are made by a:
(1) a machine
(2) a bacterium that produces methane gas
(3) a bacterium producing a large amount of carbon dioxide
(4) a fungus that releases a lot of gases during its metabolic activites.
.
.
Answer ▽ ✅Verified
(3) a bacterium producing a large amount of carbon dioxide
Cheese, is one of the oldest food items in which
microbes were used. Different varieties of cheese are known by their
characteristic texture, flavour and taste, the specificity coming from the
microbes used. For example, the large holes in ‘Swiss cheese’ are due to
production of a large amount of CO2 by a bacterium named
Propionibacterium sharmanii. The ‘Roquefort cheese’ are ripened by
growing a specific fungi on them, which gives them a particular flavour.
microbes were used. Different varieties of cheese are known by their
characteristic texture, flavour and taste, the specificity coming from the
microbes used. For example, the large holes in ‘Swiss cheese’ are due to
production of a large amount of CO2 by a bacterium named
Propionibacterium sharmanii. The ‘Roquefort cheese’ are ripened by
growing a specific fungi on them, which gives them a particular flavour.
Microbes produce different types of gaseous end-products during
growth and metabolism. The type of the gas produced depends upon the
microbes and the organic substrates they utilise. In the examples cited in
relation to fermentation of dough, cheese making and production of
beverages, the main gas produced was CO2..
The dough, which is used to make bread, is fermented by
yeast called Saccharomyces cerevisiae. Certain dishes such as idli and
dosa, are made from dough fermented by microbes. Bacteria and fungi
are used to impart particular texture, taste and flavor to cheese.
⬆️Prev____@organised notes_____Next⬇️
.Match the following list of bacteria and their commercially important products:
| Bacterium |
| Product |
(i) | Aspergullus niger | (a) | Lactic acid |
(ii) | Acetobacter aceti | (b) | Butyric acid |
(iii) | Clostridium Butylicum | (c) | Acetic acid |
(iv) | Lactobacillus | (d) | Citric Acid |
Choose the correct match:
(1) (i) - b, (ii) - c, (iii) - d, (iv) - a
(2) (i) - b, (ii) - d, (iii) - c, (iv) - a
(3) (i) - d, (ii) - c, (iii) - b, (iv) - a
(4) (i) - d, (ii) - a, (iii) - c, (iv) - b
.
.
Answer ▽ ✅Verified
(3) (i) - d, (ii) - c, (iii) - b, (iv) - a
Chemicals, Enzymes and other Bioactive Molecules
Microbes are also used for commercial and industrial production of
certain chemicals like organic acids, alcohols and enzymes. Examples of
acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of
butyric acid and Lactobacillus (a bacterium) of lactic acid.
Yeast (Saccharomyces cerevisiae) is used for commercial production
of ethanol. Microbes are also used for production of enzymes. Lipases are
used in detergent formulations and are helpful in removing oily stains
from the laundry. You must have noticed that bottled fruit juices bought
from the market are clearer as compared to those made at home. This is
because the bottled juices are clarified by the use of pectinases and
proteases. Streptokinase produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing
clots from the blood vessels of patients who have undergone myocardial
infarction leading to heart attack.
Another bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients, is produced by
the fungus Trichoderma polysporum. Statins produced by the yeast
Monascus purpureus have been commercialised as blood-cholesterol
lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol.
⬆️Prev____@organised notes_____Next⬇️
.The free-living fungus Trichoderma can be used for:
(1) killing insects
(2) biological control of plant diseases
(3) controlling butterfly caterpillars
(4) producing antibiotics
.
.
Answer ▽ ✅Verified
(2) biological control of plant diseases
Deuteromycetes
Commonly known as imperfect fungi because only the asexual orvegetative phases of these fungi are known. When the sexual forms of
these fungi were discovered they were moved into classes they rightly
belong to. It is also possible that the asexual and vegetative stage have
been given one name (and placed under deuteromycetes) and the sexual
stage another (and placed under another class). Later when the linkages
were established, the fungi were correctly identified and moved out of
deuteromycetes. Once perfect (sexual) stages of members of
dueteromycetes were discovered they were often moved to ascomycetes
and basidiomycetes. The deuteromycetes reproduce only by asexual spores
known as conidia. The mycelium is septate and branched. Some members
are saprophytes or parasites while a large number of them are
decomposers of litter and help in mineral cycling. Some examples are
Alternaria, Colletotrichum and Trichoderma.
Chemicals, Enzymes and other Bioactive Molecules
Microbes are also used for commercial and industrial production ofcertain chemicals like organic acids, alcohols and enzymes. Examples of
acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of
butyric acid and Lactobacillus (a bacterium) of lactic acid.
Yeast (Saccharomyces cerevisiae) is used for commercial production
of ethanol. Microbes are also used for production of enzymes. Lipases are
used in detergent formulations and are helpful in removing oily stains
from the laundry. You must have noticed that bottled fruit juices bought
from the market are clearer as compared to those made at home. This is
because the bottled juices are clarified by the use of pectinases and
proteases. Streptokinase produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing
clots from the blood vessels of patients who have undergone myocardial
infarction leading to heart attack.
Another bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients, is produced by
the fungus Trichoderma polysporum. Statins produced by the yeast
Monascus purpureus have been commercialised as blood-cholesterol
lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol.
MICROBES AS BIOCONTROL AGENTS
A biological control being developed for use in the treatment of plant
disease is the fungus Trichoderma. Trichoderma species are free-living
fungi that are very common in the root ecosystems. They are effective
biocontrol agents of several plant pathogens
⬆️Prev____@organised notes_____Next⬇️
.Identify the incorrectly matched pair
1. | Baculoviruses | Species specific, broad spectrum insecticides |
2. | Trichoderma | Free living fungi common in root ecosystems |
3. | Ladybird | Biocontrol of aphids |
4. | Organic farming | Pests kept at manageable levels rather than completely eradicated |
.
.
Answer ▽ ✅Verified
1. | Baculoviruses | Species specific, broad spectrum insecticides |
MICROBES AS BIOCONTROL AGENTS
Biocontrol refers to the use of biological methods for controlling plant
diseases and pests. In modern society, these problems have been tackled
increasingly by the use of chemicals – by use of insecticides and pesticides.
These chemicals are toxic and extremely harmful, to human beings and
animals alike, and have been polluting our environment (soil, ground
water), fruits, vegetables and crop plants. Our soil is also polluted through
our use of weedicides to remove weeds.
Biological control of pests and diseases: In agriculture, there is a
method of controlling pests that relies on natural predation rather than
introduced chemicals. A key belief of the organic farmer is that biodiversity
furthers health. The more variety a landscape has, the more sustainable
it is. The organic farmer, therefore, works to create a system where the
insects that are sometimes called pests are not eradicated, but instead
are kept at manageable levels by a complex system of checks and balances
within a living and vibrant ecosystem. Contrary to the ‘conventional’
farming practices which often use chemical methods to kill both useful
and harmful life forms indiscriminately, this is a holistic approach that
seeks to develop an understanding of the webs of interaction between the
myriad of organisms that constitute the field fauna and flora. The organic
farmer holds the view that the eradication of the creatures that are often
described as pests is not only possible, but also undesirable, for without
them the beneficial predatory and parasitic insects which depend upon
them as food or hosts would not be able to survive. Thus, the use of
biocontrol measures will greatly reduce our dependence on toxic chemicals
and pesticides. An important part of the biological farming approach is
to become familiar with the various life forms that inhabit the field,
predators as well as pests, and also their life cycles, patterns of feeding
and the habitats that they prefer. This will help develop appropriate means
of biocontrol.
The very familiar beetle with red and black markings – the Ladybird,
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
A biological control being developed for use in the treatment of plant
disease is the fungus Trichoderma. Trichoderma species are free-living
fungi that are very common in the root ecosystems. They are effective
biocontrol agents of several plant pathogens.
Baculoviruses are pathogens that attack insects and other arthropods.
The majority of baculoviruses used as biological control agents are in the
genus Nucleopolyhedrovirus. These viruses are excellent candidates for
species-specific, narrow spectrum insecticidal applications. They have
been shown to have no negative impacts on plants, mammals, birds, fish
or even on non-target insects. This is especially desirable when beneficial
insects are being conserved to aid in an overall integrated pest
management (IPM) programme, or when an ecologically sensitive area is
being treated.
⬆️Prev____@organised notes_____Next⬇️
.Identify the incorrect matched pair:
(1) Trichoderma harzianum: Cyclosporin A
(2) Monascus purpureus: Statins
(3) Aspergillus niger: Citric acid
(4) Streptococcus pyogenes: Clot buster
.
.
Answer ▽ ✅Verified
(1) Trichoderma harzianum: Cyclosporin A
Chemicals, Enzymes and other Bioactive Molecules
Microbes are also used for commercial and industrial production ofcertain chemicals like organic acids, alcohols and enzymes. Examples of
acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of
butyric acid and Lactobacillus (a bacterium) of lactic acid.
Yeast (Saccharomyces cerevisiae) is used for commercial production
of ethanol. Microbes are also used for production of enzymes. Lipases are
used in detergent formulations and are helpful in removing oily stains
from the laundry. You must have noticed that bottled fruit juices bought
from the market are clearer as compared to those made at home. This is
because the bottled juices are clarified by the use of pectinases and
proteases. Streptokinase produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing
clots from the blood vessels of patients who have undergone myocardial
infarction leading to heart attack.
Another bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients, is produced by
the fungus Trichoderma polysporum. Statins produced by the yeast
Monascus purpureus have been commercialised as blood-cholesterol
lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol.
⬆️Prev____@organised notes_____Next⬇️
.Identify the incorrectly matched pair:
1 | Streptococcus | Clot buster |
2. | Monascus purpureus | Statins |
3. | Trichoderma harziamum | Immunosuppressant |
4. | Aspergillus niger | Citric acid |
.
.
Answer ▽ ✅Verified
3. | Trichoderma harziamum | Immunosuppressant |
Chemicals, Enzymes and other Bioactive Molecules
Microbes are also used for commercial and industrial production ofcertain chemicals like organic acids, alcohols and enzymes. Examples of
acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of
butyric acid and Lactobacillus (a bacterium) of lactic acid.
Yeast (Saccharomyces cerevisiae) is used for commercial production
of ethanol. Microbes are also used for production of enzymes. Lipases are
used in detergent formulations and are helpful in removing oily stains
from the laundry. You must have noticed that bottled fruit juices bought
from the market are clearer as compared to those made at home. This is
because the bottled juices are clarified by the use of pectinases and
proteases. Streptokinase produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing
clots from the blood vessels of patients who have undergone myocardial
infarction leading to heart attack.
Another bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients, is produced by
the fungus Trichoderma polysporum. Statins produced by the yeast
Monascus purpureus have been commercialised as blood-cholesterol
lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol.
⬆️Prev____@organised notes_____Next⬇️
.Baculoviruses are:
1. Species specific, narrow spectrum insecticides
2. Species specific, broad spectrum insecticides
3. Non specific, narrow spectrum inseticides
4. Non specific, broad spectrum insecticides
.
.
Answer ▽ ✅Verified
1. Species specific, narrow spectrum insecticides
MICROBES AS BIOCONTROL AGENTS
Biocontrol refers to the use of biological methods for controlling plant
diseases and pests. In modern society, these problems have been tackled
increasingly by the use of chemicals – by use of insecticides and pesticides.
These chemicals are toxic and extremely harmful, to human beings and
animals alike, and have been polluting our environment (soil, ground
water), fruits, vegetables and crop plants. Our soil is also polluted through
our use of weedicides to remove weeds.
Biological control of pests and diseases: In agriculture, there is a
method of controlling pests that relies on natural predation rather than
introduced chemicals. A key belief of the organic farmer is that biodiversity
furthers health. The more variety a landscape has, the more sustainable
it is. The organic farmer, therefore, works to create a system where the
insects that are sometimes called pests are not eradicated, but instead
are kept at manageable levels by a complex system of checks and balances
within a living and vibrant ecosystem. Contrary to the ‘conventional’
farming practices which often use chemical methods to kill both useful
and harmful life forms indiscriminately, this is a holistic approach that
seeks to develop an understanding of the webs of interaction between the
myriad of organisms that constitute the field fauna and flora. The organic
farmer holds the view that the eradication of the creatures that are often
described as pests is not only possible, but also undesirable, for without
them the beneficial predatory and parasitic insects which depend upon
them as food or hosts would not be able to survive. Thus, the use of
biocontrol measures will greatly reduce our dependence on toxic chemicals
and pesticides. An important part of the biological farming approach is
to become familiar with the various life forms that inhabit the field,
predators as well as pests, and also their life cycles, patterns of feeding
and the habitats that they prefer. This will help develop appropriate means
of biocontrol.
The very familiar beetle with red and black markings – the Ladybird,
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
A biological control being developed for use in the treatment of plant
disease is the fungus Trichoderma. Trichoderma species are free-living
fungi that are very common in the root ecosystems. They are effective
biocontrol agents of several plant pathogens.
Baculoviruses are pathogens that attack insects and other arthropods.
The majority of baculoviruses used as biological control agents are in the
genus Nucleopolyhedrovirus. These viruses are excellent candidates for
species-specific, narrow spectrum insecticidal applications. They have
been shown to have no negative impacts on plants, mammals, birds, fish
or even on non-target insects. This is especially desirable when beneficial
insects are being conserved to aid in an overall integrated pest
management (IPM) programme, or when an ecologically sensitive area is
being treated.
⬆️Prev____@organised notes_____Next⬇️
.The virus shown here is a causative agent of :
1. Intestinal infections
2. Respiratory infections
3. CNS infections
4. Genito-urinary infections
.
.
Answer ▽ ✅Verified
2. Respiratory infections
⬆️Prev____@organised notes_____Next⬇️
.Consider the following statements:
I. Statins, used as blood cholesterol lowering agents, are derived from Monascus purpureus
II. Cyclosporin A, derived from Trichoderma, is used as an immunosuressent
III. Baculoviruses, in the genus Nucleopolyhederovirus, are species specific, broad spectrum insecticides
Which of the above statements are true?
1. I and II only
2. I and III only
3. II and III only
4. I, II and III
.
.
Answer ▽ ✅Verified
1. I and II only
MICROBES AS BIOCONTROL AGENTS
Biocontrol refers to the use of biological methods for controlling plant
diseases and pests. In modern society, these problems have been tackled
increasingly by the use of chemicals – by use of insecticides and pesticides.
These chemicals are toxic and extremely harmful, to human beings and
animals alike, and have been polluting our environment (soil, ground
water), fruits, vegetables and crop plants. Our soil is also polluted through
our use of weedicides to remove weeds.
Biological control of pests and diseases: In agriculture, there is a
method of controlling pests that relies on natural predation rather than
introduced chemicals. A key belief of the organic farmer is that biodiversity
furthers health. The more variety a landscape has, the more sustainable
it is. The organic farmer, therefore, works to create a system where the
insects that are sometimes called pests are not eradicated, but instead
are kept at manageable levels by a complex system of checks and balances
within a living and vibrant ecosystem. Contrary to the ‘conventional’
farming practices which often use chemical methods to kill both useful
and harmful life forms indiscriminately, this is a holistic approach that
seeks to develop an understanding of the webs of interaction between the
myriad of organisms that constitute the field fauna and flora. The organic
farmer holds the view that the eradication of the creatures that are often
described as pests is not only possible, but also undesirable, for without
them the beneficial predatory and parasitic insects which depend upon
them as food or hosts would not be able to survive. Thus, the use of
biocontrol measures will greatly reduce our dependence on toxic chemicals
and pesticides. An important part of the biological farming approach is
to become familiar with the various life forms that inhabit the field,
predators as well as pests, and also their life cycles, patterns of feeding
and the habitats that they prefer. This will help develop appropriate means
of biocontrol.
The very familiar beetle with red and black markings – the Ladybird,
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
A biological control being developed for use in the treatment of plant
disease is the fungus Trichoderma. Trichoderma species are free-living
fungi that are very common in the root ecosystems. They are effective
biocontrol agents of several plant pathogens.
Baculoviruses are pathogens that attack insects and other arthropods.
The majority of baculoviruses used as biological control agents are in the
genus Nucleopolyhedrovirus. These viruses are excellent candidates for
species-specific, narrow spectrum insecticidal applications. They have
been shown to have no negative impacts on plants, mammals, birds, fish
or even on non-target insects. This is especially desirable when beneficial
insects are being conserved to aid in an overall integrated pest
management (IPM) programme, or when an ecologically sensitive area is
being treated.
Chemicals, Enzymes and other Bioactive Molecules
Microbes are also used for commercial and industrial production ofcertain chemicals like organic acids, alcohols and enzymes. Examples of
acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of
butyric acid and Lactobacillus (a bacterium) of lactic acid.
Yeast (Saccharomyces cerevisiae) is used for commercial production
of ethanol. Microbes are also used for production of enzymes. Lipases are
used in detergent formulations and are helpful in removing oily stains
from the laundry. You must have noticed that bottled fruit juices bought
from the market are clearer as compared to those made at home. This is
because the bottled juices are clarified by the use of pectinases and
proteases. Streptokinase produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing
clots from the blood vessels of patients who have undergone myocardial
infarction leading to heart attack.
Another bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients, is produced by
the fungus Trichoderma polysporum. Statins produced by the yeast
Monascus purpureus have been commercialised as blood-cholesterol
lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol.
⬆️Prev____@organised notes_____Next⬇️
.
A. Saccharomyces cerevisiae | 1. Production of immunosuppressive agents |
B. Monascus purpureus | 2. Ripening of Swiss Cheese |
C. Trichoderma polysporum | 3. Commercial production of ethanol |
D. Propionibacterium sharrmanii | 4. Production of blood-cholesterol lowering agents |
Codes
| A | B | C | D |
(1) | 3 | 4 | 1 | 2 |
(2) | 4 | 3 | 2 | 1 |
(3) | 4 | 2 | 1 | 3 |
(4) | 3 | 1 | 4 | 2 |
.
.
Answer ▽ ✅Verified
A | B | C | D | |
(1) | 3 | 4 | 1 | 2 |
MICROBES IN HOUSEHOLD PRODUCTS
You would be surprised to know that we use microbes or products
derived from them everyday. A common example is the production of
curd from milk. Micro-organisms such as Lactobacillus and others
commonly called lactic acid bacteria (LAB) grow in milk and convert it
to curd. During growth, the LAB produce acids that coagulate and
partially digest the milk proteins. A small amount of curd added to the
fresh milk as inoculum or starter contain millions of LAB, which at
suitable temperatures multiply, thus converting milk to curd, which
also improves its nutritional quality by increasing vitamin B12. In our
stomach too, the LAB play very beneficial role in checking diseasecausing
microbes.
The dough, which is used for making foods such as dosa and idli is
also fermented by bacteria. The puffed-up appearance of dough is due to
the production of CO2 gas. Can you tell which metabolic pathway is
taking place resulting in the formation of CO2? Where do you think the
bacteria for these fermentations come from? Similarly the dough, which
is used for making bread, is fermented using baker’s yeast
(Saccharomyces cerevisiae). A number of traditional drinks and foods
are also made by fermentation by the microbes. ‘Toddy’, a traditional
drink of some parts of southern India is made by fermenting sap from
palms. Microbes are also used to ferment fish, soyabean and bambooshoots
to make foods. Cheese, is one of the oldest food items in which
microbes were used. Different varieties of cheese are known by their
characteristic texture, flavour and taste, the specificity coming from the
microbes used. For example, the large holes in ‘Swiss cheese’ are due to
production of a large amount of CO2 by a bacterium named
Propionibacterium sharmanii. The ‘Roquefort cheese’ are ripened by
growing a specific fungi on them, which gives them a particular flavour.
MICROBES AS BIOCONTROL AGENTS
Biocontrol refers to the use of biological methods for controlling plant
diseases and pests. In modern society, these problems have been tackled
increasingly by the use of chemicals – by use of insecticides and pesticides.
These chemicals are toxic and extremely harmful, to human beings and
animals alike, and have been polluting our environment (soil, ground
water), fruits, vegetables and crop plants. Our soil is also polluted through
our use of weedicides to remove weeds.
Biological control of pests and diseases: In agriculture, there is a
method of controlling pests that relies on natural predation rather than
introduced chemicals. A key belief of the organic farmer is that biodiversity
furthers health. The more variety a landscape has, the more sustainable
it is. The organic farmer, therefore, works to create a system where the
insects that are sometimes called pests are not eradicated, but instead
are kept at manageable levels by a complex system of checks and balances
within a living and vibrant ecosystem. Contrary to the ‘conventional’
farming practices which often use chemical methods to kill both useful
and harmful life forms indiscriminately, this is a holistic approach that
seeks to develop an understanding of the webs of interaction between the
myriad of organisms that constitute the field fauna and flora. The organic
farmer holds the view that the eradication of the creatures that are often
described as pests is not only possible, but also undesirable, for without
them the beneficial predatory and parasitic insects which depend upon
them as food or hosts would not be able to survive. Thus, the use of
biocontrol measures will greatly reduce our dependence on toxic chemicals
and pesticides. An important part of the biological farming approach is
to become familiar with the various life forms that inhabit the field,
predators as well as pests, and also their life cycles, patterns of feeding
and the habitats that they prefer. This will help develop appropriate means
of biocontrol.
The very familiar beetle with red and black markings – the Ladybird,
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
and Dragonflies are useful to get rid of aphids and mosquitoes,
respectively. An example of microbial biocontrol agents that can be
introduced in order to control butterfly caterpillars is the bacteria Bacillus
thuringiensis (often written as Bt ). These are available in sachets as dried
spores which are mixed with water and sprayed onto vulnerable plants
such as brassicas and fruit trees, where these are eaten by the insect
larvae. In the gut of the larvae, the toxin is released and the larvae get
killed. The bacterial disease will kill the caterpillars, but leave other insects
unharmed. Because of the development of methods of genetic engineering
in the last decade or so, the scientists have introduced B. thuringiensis
toxin genes into plants. Such plants are resistant to attack by insect pests.
Bt-cotton is one such example, which is being cultivated in some states
of our country.
A biological control being developed for use in the treatment of plant
disease is the fungus Trichoderma. Trichoderma species are free-living
fungi that are very common in the root ecosystems. They are effective
biocontrol agents of several plant pathogens.
Baculoviruses are pathogens that attack insects and other arthropods.
The majority of baculoviruses used as biological control agents are in the
genus Nucleopolyhedrovirus. These viruses are excellent candidates for
species-specific, narrow spectrum insecticidal applications. They have
been shown to have no negative impacts on plants, mammals, birds, fish
or even on non-target insects. This is especially desirable when beneficial
insects are being conserved to aid in an overall integrated pest
management (IPM) programme, or when an ecologically sensitive area is
being treated.
Chemicals, Enzymes and other Bioactive Molecules
Microbes are also used for commercial and industrial production ofcertain chemicals like organic acids, alcohols and enzymes. Examples of
acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of
butyric acid and Lactobacillus (a bacterium) of lactic acid.
Yeast (Saccharomyces cerevisiae) is used for commercial production
of ethanol. Microbes are also used for production of enzymes. Lipases are
used in detergent formulations and are helpful in removing oily stains
from the laundry. You must have noticed that bottled fruit juices bought
from the market are clearer as compared to those made at home. This is
because the bottled juices are clarified by the use of pectinases and
proteases. Streptokinase produced by the bacterium Streptococcus and
modified by genetic engineering is used as a ‘clot buster’ for removing
clots from the blood vessels of patients who have undergone myocardial
infarction leading to heart attack.
Another bioactive molecule, cyclosporin A, that is used as an
immunosuppressive agent in organ-transplant patients, is produced by
the fungus Trichoderma polysporum. Statins produced by the yeast
Monascus purpureus have been commercialised as blood-cholesterol
lowering agents. It acts by competitively inhibiting the enzyme responsible
for synthesis of cholesterol.
Fermented Beverages
Microbes especially yeasts have been used fromtime immemorial for the production of beverages
like wine, beer, whisky, brandy or rum. For this
purpose the same yeast Saccharomyces
cerevisiae used for bread-making and
commonly called brewer’s yeast, is used for
fermenting malted cereals and fruit juices, to
produce ethanol. Do you recollect the metabolic
reactions, which result in the production of
ethanol by yeast? Depending on the type of the
raw material used for fermentation and the type
of processing (with or without distillation)
different types of alcoholic drinks are obtained.
Wine and beer are produced without distillation
whereas whisky, brandy and rum are produced
by distillation of the fermented broth.
⬆️Prev____@organised notes____End
