Biology Chapter 10 Microbes In Human Welfare

(ii) Vitamin B₁₂ or cobalamine is produced by lactobacillus and actinomycetes.

2. Streptococcus thermophilus.

2. Statin is produced by Aspergillus.

2. The puffed up appearance of dough is due to the production of C0₂ gas by yeast, Saccharomyces cerevisiae.

3. Methane, H₂S and C0₂ are produced during microbial digestion of organic compounds in case of secondary treatment of sewage.

Example : Penicillin produced by Penicillium chrysogenum is active against various species of Staphylococci and Streptococci.

(ii) Cephalosporium

Roquefort cheese — Penicillium roqueforti.

(ii) Without distillation — Wine, Beer.

Secondary treatment of waste involves the biological removal of dissolved organic matter. It involves the use of microbes. It is an expensive process.

Examples. -  Methanococcus and Methanospirillum.

(i) the anaerobic sludge (ii) rumen of cattle

(iii) marshy places (iv) flooded rice fields.

Significance

1. Baculo viruses are highly suitable for species-specific and narrow spectrum insecticides.

2. They have no negative impacts on plants, birds, mammals or even other non-target insects.

Five micro-organisms used as biofertilizers are-:
1.Rhizobium
2.Azotobacter
3.Azospirillum
4.Cyanobacteria
5.Phosphate solubilizing bacteria

COD (Chemical oxygen demand) determines the milligrams of oxygen per litre of waste water which are consumed during the oxidation of the organic matter to give carbon dioxide, ammonia, and water.

For exampls- Extracts from neem (Azadirachta indica) contain a compound, azadirachtin that keeps away the insects. Foliage coated with extract of neem repel Japanese beetles and leaf eating pests.

Few examples of biopesticides are :

i. Azadirachtin from neem plants is used as an biopesticide
ii. Bacillus thuringiensis is used as an biopesticide in cotton plants

Micro-organisms used are Bacteria, cyanobacteria and fungi.

Symbiotically nitrogen fixing organisms

1. Rhizobium leguminosarum.

2. Nostoc (Cyanobacteria).

Asymbiotically nitrogen fixing organisms

1. Free living aerobic bacteria—Azotobacter

2. Free living photosynthetic—Chlorobium.

(i) They are safe to use and are biological in origin.

(ii) They do not spoil the quality of the soil and are target specific instead increases its fertility.

(iii) They do not pollute the atmosphere and are non-poisonous.

(iv) They are less expensive and are biodegradable.

(b) Soil- Microbes in the soil play an important role in increasing the fertility of the soil. Microbes breakdown the oraganic materials and enrich the soil with nutrients. Rhizobium is a symbiotic bacteria which helps to fix nitrogen in leguminous plants. 

2. Biogas. It is an ecofriendly gas which is used as a fuel. The slurry produced by its production is used as a manure.

3. Citric acid. It is used as preservative in many food items.

4. Curd. It is a dairy product which is a rich source of vitamin B_^12.

1. Primary Treatment. It includes physical processing, such as sedimentation, floatation, shredding (fragmenting and filtering). These processes remove most of the large debris. The primary sludge obtained when all the solids settle down is sent for secondary treatment.

2. Secondary Treatment. It is a biological method in which micro-organisms are used.

Activated Sludge Method. Sewage, after primary treatment, is pumped into an aeration tank or oxidation pond where it is mixed with air and sludge containing bacteria. Bacteria forms flocs along with fungus . The flocs sediment and form activated sludge. A part of activated sludge is used as an inoculum and pumped back. The remaining sludge is pumped into anaerobic sludge digesters where bacteria decomposes the organic matter and releases a mixture of gases that forms biogas. 

Bacillus thuringinesis has been used as a biological control of pests. The bacteria Bacillus thuringiensis are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees. These bacteria produce a cry protein which when eaten by insects, release toxin in their gut and the larvae gets killed. The  scientists have been able to introduce B. thuringiensis toxin genes into plants with the help of genetic engineering. 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.

1. Anabaena, a cyanobacterium increases the fertility, enriches soil with organic material and fixes nitrogen. 

2. Rhizobium also fix atmospheric nitrogen as nitrates and nitrites and lives as a symbiont in the roots of leguminous plants.

3. Mycorrhizae formed by association of bacteria and roots of higher plants increase soil fertility.

Biogas plant.
1. The plant consists of well-like underground tank made of bricks. This tank is called digester.
2. The roof of the digester is dome-shaped made of cement and bricks. The dome of the digester tank acts as a gas holder (or storage tank for biogas). Thus, the gas holder in this type of gas-plant is fixed.
3. There is a gas outlet at the top of dome for the supply of biogas.
4. On the one side of digester tank, there is a slopping inlet tank and on the other side there is a rectangular outlet tank, or overflow tank. Both these tanks are made of cement and bricks.
5. Mixing tank is connected with slopping inlet chamber (or tank) while outflow tank is connected with rectangular outlet chamber (or tank).
6. The inlet-chamber is for introducing fresh dung slurry into the main digester tank whereas the outlet chamber is for taking out spent dung slurry after extraction of biogas.

Fig. Biogas plant

Uses of Lactobacillus.
1. It produces large amount of lactic acid, due to which they are used in the production of fermented food.
2.They also improve the nutritional quality of curd by increasing vitamin B₁₂.
3. Kaffir beer is prepared from Sorghum by Lactobacillus delbreuckii.
4. Yoghurt is prepared from milk by Lactobacillus bulgaricus and Kefir (fermented milk) is prepared from milk by Lactobacillus sp.
5. LAB are also found in human stomach where they prevent the growth and multiplication of certain disease causing microbes.

B.

C.

A.

B.

A.

A.

D.

C.

D.

A.

B.

D.

The products obtained from:

(a)  LAB - Lacto acid bacteria is used in the production of curd from milk.

(b)  Saccharomyces cerevisiae is used for the production of ethanol.

(c)  Propionibacterium sharmanii is used in the production of Swiss cheese.

(d)  Aspergillus niger is used in production of citric acid.

Following three microbes can be chosen for organic farming:

1. Mycorrhiza: It helps in the absorption of phosphorous from the soil.

2. Anabaena: It is involved in the process of nitrogen fixation.

3. Rhizobium: It fixes nitrogen into organic forms, which can be used by the plant as nutrient.

The application of the following are:

1. Monascus:  It is produces Statins that are used commercially as blood-cholesterol lowering agents.

2. Methanobacterium: It is used in the biological generation of methane by anaerobic processes.

Bioreactor

A bioreactor is an apparatus in which a biological reaction or a process is carried out. They are the vessels in which raw materials are biologically converted into specific products, individual enzymes etc.

Following are the applications of bioreactors:

i. They are used to produce large quantities of products like proteins or enzymes.

ii. They are also used to produce beverages like alcohol.

Two commonly used bio reactors are

(a) Simple stirred-tank bioreactor.

(b) Sparged stirred-tank bioreactor.

Importance of Bioreactor

i. Bioreactors are used for processing large volumes of cultures (100 - 1000 litres) which produce large quantities of products.

ii. It also provides optimum growth conditions like temp, pH, substrate, salts, vitamins and oxygen for achieving the desired product.

Streptokinase enzyme is produced by the bacterium Streptococcus. It is modified by genetic engineering and is used as a clot buster for removing clots from the blood vessels of patients who have suffered from myocardial infarction.

Mycorrhizae is symbiotic association of fungus and higher plants. The fungus absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development. Thus it acts as a biofertilizer.

Bacteria and fungi are two categories of naturally occurring microbes present in sewage. The bacteria along with the fungal mycelia form flocs. These flocs are utilised during the secondary treatment of sewage. The primary effluent after separation of the grit and debris is taken to the secondary treatment. Here, the effluent is passed to an aeration tank where it is constantly agitated and air is pumped into it. This leads to vigorous growth of bacteria and floc formation, the bacteria in these flocs consume of organic matter; thus decreasing the BOD of the sewage.

The introduction of sewage caused a sudden and sharp drop in the amount of dissolved oxygen in the river. This is caused due to an increase in the biological oxygen demand (BOD). This in turn leads to the death of fishes and other aquatic life. As the sewage gets diluted due the flow of the water, the river slowly regains some of its oxygen concentration.

The sequences of events occurring in a biogas plant are:

(i) Hydrolysis: Through hydrolysis the complex organic molecules are broken down into simple sugars, amino acids and fatty acids.

(ii) Acidogenesis: In this step further breakdown of the remaining components by acidogenic (fermentative) bacteria takes place.

(iii) Acetogenesis: In this step simple molecule obtained by acidogenesis phase are further digested by acetogens, to produce largely acetic acid as well as carbon dioxide and hydrogen.

(iv) Methanogenesis: In this step methanogens utilize the intermediate products of the previous stages and convert them into methane, carbon dioxide and water.

The parts of biogas plant:

The part labelled (a) is sludge

The part labelled (b) is a gas holder, and

The part labelled (c) is inlet to feed slurry

The primary phase of sewage treatment involves physical removal of particles by filtration and sedimentation.
Different steps involved during the primary treatment are as follows:

i. Initially, floating debris of sewage water is removed by sequential filtration.

ii. Then, grit (soil and small pebbles) are removed by sedimentation.

Streptococcus: produces streptokinase enzyme. This enzyme is used as a ‘Clot Buster’  that is used to dissolve and removes clots formed in the blood vessels of patients who have had a heart attack.
Monascus: produces statins that act as blood cholesterol lowering agents. They act by competitively inhibiting the enzyme responsible for the synthesis of cholesterol.

Cyanobacteria such as Anabaena and Nostoc are free-living and help fix atmospheric nitrogen and act as bio-fertilizers especially in paddy fields.

Cyclosporin A, is produced by the fungus Trichoderma polysporum.  Cyclosporin-A is a bioactive molecule which is used as an immunosuppressive agent in organ-transplant patients.

Free-living -  Azotobacter, Symbiotic - Rhizobium serve as bio-fertilizers.
They are called bio-fertilizers because they are organisms found in nature that enrich the nutrient quality of the soil.

After the primary treatment, the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it.This leads to the vigorous growth of useful aerobic microbes (Flocs of bacteria and fungi). The microbes consume a major portion of the organic matter of the effluent and thus reduce the BOD significantly.

The usefulness of various micro-organisms to humans - :
(a) Nucleopolyhedrovirus - It is a biological control agent and is used as a species-specific insecticide.

(b) Saccharomyces cerevisiae - It is used to ferment bread dough.
It is used in the preparation of ethanol by fermenting fruit juices and cereals.
(c) Monascuspurpureus - Statins produced by it work as blood cholesterol lowering agents.

(d) Trichoderma polysporum - It produces cyclosporin A, which is used as an immunosuppressant.

(e) Penicillium notatum - It is a source of penicillin, an antibiotic.

(f) Propionibacterium sharmanii - It helps in the ripening of swiss cheese. It produces large amount of CO₂ and thus is responsible for the appearance of large holes in the cheese.

Baculoviruses belongs to the genus Nucleopolyhedrovirus.
Baculoviruses is regarded as natural pest management microorganism. They show activity against wide range of species-specific pathogen. These viruses can attack wide range of arthropod and some other insects. Most importantly these viruses don't show any negative impact on plants, mammals, birds, fish etc and is beneficial for Integrated pest management (IPM) or in ecologically sensitive area.

Single Cell Protien

(a) Statin : - Monascus purpureus (fungus)
(b) Citric acid : - Aspergillus niger (fungi)
(c) Penicillin : - Pencillium notatum (fungi)
(d) Butyric acid : - Clostridium butylicum (Bacteria)

(a) Azospirillum, Azotobacter, Anabaena, Oscillatoria, etc.

(b) Leguminous crops have a symbiotic association with Rhizobium bacteria which traps N₂ directly from the atmosphere and provides it to the plant and in turn gets food and shelter.

Biological pest control has important advantages compared to chemical pest control, such as being safer for humans and the environment.

Chemical methods often kill both useful and harmful life forms indiscriminately. Eradication of the creatures that are often described as pests in 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.

The bacterium, a fungus and insects that are used as biocontrol agents are:

Insects = Ladybird and Dragonflies.

Bacteria = Bacillus thuringiensis

Fungus   = Trichoderma

A.

Aspergillus

A good producer of citric acid is Aspergillus niger (a fungus). Clostridium produces butyric acid, Saccharomyces cerevisiae is used for bread baking fermenting malted cereals and fruit juices to produce ethanol. Pseudomonas (a bacterium) is used in Vitamin -B-12 production.

A.

Codes
 A   B   C    D
3    4    1    2

D.

blood cholesterol-lowering statins

Monascus purpureus is a yeast used in the production of statins which are blood cholesterol lowering agents. 

B.

streptokinase

D.

They show contact inhibition

Contact inhibition is the natural process of arresting cell growth when two or more cells come in contact with each other. It is a property of normal cells. Cancer cells divide in uncontrolled manner and do not show contact inhibition. 

C.

Diplotene

Rennin or chymosin is a protease found in rennat. It cause cleavage of a specific linkage i.e., the peptide bond between 105 and 106 phenyl alanine and methionine and K-casein the native substrate of this enzyme. Thus, its pressure helps in the conversion of milk into curd via chaging the caesin protein of milk into caesinate.

B.

facilitated transport

Thus, facilitated transport is the process of spontaneous passive transport of the molecules or ions across a biological membrane via specific transmembrane integral protein.

C.

Glomus

Several species of Glomus, including G. aggregatum, are cultured and sold as mycorrhizal inoculant for agricultural soils. Being endomycorrhiza, it helps the plants in the absorption of nutrients especially phosphorus from soil. 

C.

Yeast used in making bread and beer is a fungus.

Yeast or Saccharomyces cerevisiae is a fungus of class-Ascomycetes. Saccharomyces sp are widely used in baking and brewing industries. Paramecium and Plasmodium belong to kingdom-fungi. Lichen is a composite organism formed from the symbiotic assocaition of algae and fungi. 
Nostoc and Anabaena are examples of cyanobacteria (or blue-green algage).

C.

bread and beer

Saccharomyces cerevisiae is known as baker's yeast and Saccharomyces elliposidens is called wine yeast. These are used in baking and brewing industry respectively.

B.

Anabaena

C.

Bt-cotton to increase cotton yield

Bt cotton is Genetically Modified (GM) cotton which has an incorporated gene extracted from the bacterium Bacillus thuringiensis. This gene codes for Bt toxin in plant tissues which is harmful only to a small fraction of insects, most notably the larvae of lepidopterans, moths, butterflies, beetles, flies, etc and harmless to other forms of life. So, it is used as biological control of pests/diseases.

B.

Methane hydrogen sulphide and CO₂

Anaerobic digestion is a bacterial process that breaks down organic material within the waste in the absence of oxygen. Municipal sewage treatment facilities also use sludge digesters. In anaerobic sludge digesters, bacteria produce a vital mixture of gases like methane, hydrogen, sulphide and carbon dioxide. 
Generally, equation for anaerobic sludge digestion is 
Organic matter + combined oxygen --> Anaerobic microbes + New cell + Energy +CH₄ + CO₂ +Other gases

B.

methane

Biogas is a methane rich fuel gas produced by anaerobic breakdown of biomass with the help of methanogenic bacteria. It is composed of methane (50-70%), CO₂(30-40%) and traces of H₂, N₂ and H₂S.

A.

Caecum

Caecum is the proximal part of large intestine. It is connected to colon (the largest part of large intestine). Colon does not contain digestive gland but feed on indigestible matter, some of them are symbiotic. They produce vitamin-K and vitamin-B complex.

D.

Statements (I), (II)

Spirulina is a fast growing non-toxic blue-green alga rich in proteins, vitamin-B complex and minerals. It is cultivated in tanks as important traditional food. Mushrooms are rich source of vitamins proteins and minerals. 

C.

Marsh gas

The decomposition of sludge by anaerobic bacteria in sewage-treatment processes produces marsh gas(methane).

D.

Glomus

Glomus is an arbuscular mycorrhizal (AM) fungi. It helps in nutrient uptake mainly the absorption of phosphorus.

D.

oxidise ammonia to nitrates

The outermost cell layer of the endosperm (3n) of seed is called aleurone layer. Since the cells of aleurone layer are triploid, the number of chromosomes would be = 63, as root tip cells (2n) has 42 chromosomes.

C.

biological process

In secondary or biologicial treatement of municipal waste rich in sewage, the organic matter is decomposed with the help of microbes. Decomposition of oragnic matter occurs by one of the three methods- water hyacinth pod, trickling filter method and activated sludge method. After decomposition the treated water is sterilized through chlorination.

D.

Agrobacterium

Agrobacterium is a Gram negative bacterium that causes tumours in plants. It is well known for its ability to transfer DNA between itself and plants, and for this reasin it has become an important tool for genetic engineering. A. tumefaciens causes crown-gall disease in plants. It has Ti- plasmid.

C.

molasses

Molasses is viscous by - the products of the processing of sugarcane, grapes or sugar beets in sugar. It is the most common substrate used in distilleries for the production of ethanol. It can be used as the base material for fermentation into rum. In Australia, molasses is ferme produce ethanol for use as an alternative fuel in motor vehicles.