Notes-Part-3-Class-12-Biology-Chapter-11-Enhancement in Food Production-Maharashtra Board

Enhancement in Food Production

Maharashtra Board-Class-12th-Biology-Chapter-11


Topics to be Learn : Part-1

  • Improvement in Food Production
  • Plant breeding
  • Tissue culture
  • Single cell protein (SCP)
  • Biofortification

Topics to be Learn : Part-2

  • Animal husbandry

Topics to be Learn : Part-3

  • Microbes in human welfare
  • Role of Microbes in Industrial Production
  • Microbes in Sewage Treatment
  • Microbes in Energy Generation
  • Role of Microbes as Biocontrol Agents
  • Role of Microbes as Biofertilizers

Microbes in human welfare :

Biotechnology: It is defined as applications of ‘Scientific and Engineering principles for the processing of materials by biological agents to provide goods and service to humans or for human welfare’.

Application of microbes :

  • Variety of microorganisms like algae, fungi, bacteria, viruses, protozoans, nematodes, etc. and their products are used for welfare of humans in regard to food, health, industry, agriculture, medicine, biocontrol, etc.
  • These organisms are used variously in food and feed technology, industry, waste utilization, energy, etc.

Microbes in food preparation :

Microbes in food preparation :

Many food preparations made at home involves the use of microorganisms.

  • The microbes Lactobacilli are used in the preparation of dhokla from gram flour and buttermilk by the process of fermentation.
  • Dosa and idlis are prepared by using batter of rice and black gram which is fermented by air borne Leuconostoc and Streptococcus bacteria.
  • Large, fleshy fruiting bodies of some mushrooms and truffles are directly used as food. It is sugar free, fat free food rich in proteins, vitamins, minerals and amino acids. It is food with low calories.
  • Curd is prepared by inoculating milk with Lactobacillus acidophilus. Lactic acid produced during fermentation causes coagulation and partial digestion of milk protein casein and milk turns into curd.
  • Buttermilk is the acidulated liquid left after churning of butter from curd, is called buttermilk.
  • Cheese : The milk is coagulated with LAB. The curd formed is filtered to separate whey and the solid mass is then ripened with growth of mould that develops flavour in it.
  • Roquefort cheese : Ripened by blue-green mold Penicillium roquefortii
  • Camembert cheese: Ripened by blue-green mold Penicillium camembertii
  • Swiss cheese : Ripened by Propionibacterium shermanii. The large holes in Swiss cheese are developed due to production of a large amount of CO2


Role of Microbes in Industrial Production :

Production on an industrial scale requires growing microbes in very large vessels, called fermenters.

The main function of a fermenter is to provide a controlled environment for growth of a microorganism, or a defined mixture of microorganisms, to obtain the desired product

  • During fermentation, variety of products like alcoholic beverages, organic acids, vitamins, growth hormones, enzymes, antibiotics, etc. are produced.
  • They are secondary metabolites produced during idio phase and are not required for their growth.
  • A specific secondary metabolite is produced depending on the type of microorganism and the type of substrate.
  • Statins produced by yeast Monascus purpureus are blood cholesterol lowering agents. They are competitive inhibitors of the enzyme that catalyzes synthesis of cholesterol.

Production of Alcoholic Beverages :

Production of Alcoholic Beverages :

  • Alcoholic beverages are the products of alcoholic fermentation of particular substrates.
  • Tubular tower fermenters are used to produce alcoholic beverages on a large scale.
  • Beer is produced from barley by fermentation.
  • For the production of beer, strains of Saccharomyces cerevisiae are used.
  • Wine is prepared from grapes.
  • Whisky is prepared by fermenting mixed grains of wheat, barley and corn followed by the distillation of the products of fermentation.
  • Liquors like beer, wine are produced without distillation.
  • Whisky, rum and brandy are distilled alcoholic beverages.
  • Traditional drinks Toddy is prepared by fermenting the sugar sap extracted from palms and coconut palms. Fenny is fermented by fleshy pedicels of cashew fruits.


Production of Organic acids :

Production of organic acids:

Microbes are used in the production of a number of organic acids.

  • Aspergillus niger — Citric acid
  • Aspergillus niger — Gluconic acid
  • Rhizopus arrhizus — Fumaric acid
  • Acetobacter aceti — Acetic acid (vinegar)


Production of vitamins :

Production of vitamins :

Vitamins : Organic nitrogenous compounds capable of performing many life-sustaining functions inside our body.

The microbes are involved in the industrial production of vitamins like thiamine (vitamin B1), riboflavin (vitamin B2), pyridoxine, folic acid, pantothenic acid, biotin, vitamin B12, ascorbic acid (Vitamin C), beta-carotene (provitamin A) and ergosterol (provitamin D).

Examples of some vitamins produced by fermentation using different microbial sources are :

  • Vitamin B2— Neurospora gossypii, Eremothecium ashbyi
  • Vitamin B12 — Pseudomonas denitrificans
  • Vitamin C — Aspergillus niger


Production of Antibiotics :

Production of Antibiotics :

  • Antibiotics are secondary metabolites produced in small amounts by certain microbes (like bacteria, fungi and few algae), which inhibit growth of other microbial pathogens.
  • They are used in treatment of deadly diseases like plague, whooping cough, diphtheria, leprosy, etc.


Some common antibiotics and their microbial sources :

Some common antibiotics and their microbial sources are as follows :

Antibiotic produced Microbial sources
Chloromycetin Streptomyces venezuelae
Erythromycin Streptomyces erythreus
Penicillin Penicillium chrysogenum
Streptomycin Streptomyces griseus
Griseofulvin Penicillium griseofulvum
Bacitracin Bacillus licheniformis
Oxytetracycline / Terramycin Streptomyces aurifaciens


Production of Enzymes :

Enzymes play a key role in metabolic reactions, these are essential for the survival of living beings.

Enzymes : Enzymes are biocatalyst proteins which accelerate biochemical processes.

  • Many microbes synthesize and excrete large quantities of enzymes into the surrounding medium. Using this feature of these tiny organisms, many enzymes are produced commercially. These enzymes are Amylase, Cellulase, Protease, Lipase, Pectinase, Streptokinase etc.

Enzyme and Microbial source :

Uses of enzymes in various industries :

  • Textile industry : To improve the quality of the fabrics.
  • Pulp and paper industry: Biomechanical pulping and bleaching.
  • Food industry : Fermentation for the production of bread and drinks such as wine and beer,
  • Detergent industry : Lipase is used because of superior cleaning properties, to increase the brightness and to remove oil stains.
  • The extraction of substances like carotenoids and olive oil.
  • Enzymes are also used in cosmetics, animal feed and agricultural industries, among others.
  • Streptokinase has fibrinolytic effect. Hence, it is used as a ‘clot buster’ in blood vessels of heart patients.


Enzyme and Microbial source :

Name of the enzyme and Microbial source

  • Invertase : Saccharomyces cerevisiae
  • Pectinase : Sclerotinia libertine, Aspergillus niger
  • Lipase : Candida lipolytica
  • Cellulase : Trichoderma konigii


Gibberellin production:

Gibberellin is a group of growth hormones mainly produced by higher plants and fungi to promote growth by stem elongation.

Applications of gibberellins :

Applications of gibberellins are as follows :

  • Gibberellins induce parthenocarpy in fruits like pear and apple.
  • Gibberellins promote growth by stem elongation.
  • They break the dormancy of seeds.
  • They induce flowering in long day plants in short day conditions.
  • They are used to enlarge the size of grapes.


Microbes in Sewage Treatment :

Sewage is the waste matter carried off on drainage.

Composition of sewage :

  • Composition of sewage varies depending upon its industrial source. e.g. textile, chemicals, pharmaceuticals, dairy, canning, brewing, meat packing, tannery, oil refineries and meat industries, etc.
  • Sewage consists of human excreta, animal dung, household waste, slaughter house waste, dissolved organic matter, algae, nematodes, pathogenic bacteria, viruses and protozoa, discharged waste water from hospitals, industries (contains toxic dissolved organic and inorganic chemicals), tannery and pharmaceutical waste, etc.
  • Sewage consists of about water (99.5% to 99.9%) and inorganic and organic matter (0.1 to 0.5%) in suspended and soluble form.

Microorganisms in Sewage:

  • It contains bacteria from soil and pathogenic microorganisms (bacteria, viruses and protozoa) causing dysentery, cholera, typhoid, polio and infectious hepatitis and soil bacteria.
  • Bacteria in sewage include coliforms, fecal Streptococci, anaerobic spore forming Bacilli and other types originating in the intestinal tract of humans.

Sewage treatment :

Sewage treatment :

Before waste water is made available for human use, it has to be treated properly, so as to remove organic matter, inorganic salts and pathogens as well.

Sewage treatment process includes four basic steps :

  • Preliminary Treatment: It includes Screening and Grit Chamber.
  • Primary treatment (physical treatment) : It involves treatment of sewage in primary sedimentation tanks.
  • Secondary treatment (biological treatment): It includes treatment of sewage in aeration tanks.
  • Tertiary treatment : It involves passage of sewage water through settling tank and anaerobic sludge digesters.

Effluents from these digesters are released in natural water bodies like rivers and streams after chlorination which kills pathogenic bacteria. Digested sludge is then disposed.


Microbes in Energy Generation :

  • Biogas is used as a fuel for domestic as well as industrial purpose.
  • It is a non-conventional and renewable source of energy and is obtained by microbial fermentation.
  • Biogas is a mixture of methane CH4 (50-60%), CO2 (30-40%), H2S (0-3%) and other gases (CO, N2, H2) in traces.
  • Biogas is highly inflamable and is used as a source of energy.

Substrates used for biogas production : Cattle dung (most commonly used substrate, a rich source of cellulose from plants), plant wastes, animal wastes, domestic wastes, agriculture waste, municipal wastes, forestry wastes, etc.

Biogas Production :

Biogas Production :

  • Most commonly used models of biogas plants are developed by KVIC (Khadi and Village Industries Commission) and IARI (Indian Agricultural Research Institute).
  • A typical biogas plant consists of digester and gas holder.
  • Raw materials like cow dung is mixed with water in equal proportion to make slurry which is fed into the digester through a side opening (charge pit).

Anaerobic digestion involves three processes : Hydrolysis or solublization, acidogenesis and methanogenesis.

  • Hydrolysis or solubilization : In initial stage raw material (cattle dung) is mixed with water in equal proportion to make slurry which is then fed into the digester. Here anaerobic hydrolyzing bacteria like Clostridium and Pseudomonas hydrolyse carbohydrates into simple sugars, proteins into amino acids and lipids into fatty acids.
  • Acidogenesis : Facultative and obligate anaerobic, acidogenic bacteria convert simple organic substances into acids like formic acid, acetic acid, H2 and CO2
  • Methanogenesis : Anaerobic methanogenic bacteria like Methanobacterium, Methanococcus convert acetate, H2 and CO2 into Methane, CO2 and H2O and other products.

12 mol CH3COOH —> 12CH4 + 12CO2

4 mol H.COOH —> CH4 + 3CO2 + 2H2O

CO2 + 4H2 —> CH4 + 2H2O


Benefits of biogas :

Benefits of biogas :

  • Biogas is a cheap, safe and renewable source of energy.
  • It can be easily generated, stored and transported.
  • It can be used for domestic lighting, cooking, street lighting as well as small scale industries.
  • It burns with blue flame and without smoke.
  • It helps to improve sanitation of the surrounding.
  • It is eco-friendly and does not cause pollution.
  • Sludge which is left over is used as a fertilizer.


Role of Microbes as Biocontrol Agents:

The natural method of eliminating and controlling insects, pests and other diseasecausing agents, is by using their natural, biological enemies. This is called biocontrol or biological control.

Biocontrol agents : Microbes (bacteria, fungi, viruses and protozoans) act as biocontrol agents in three ways : they cause the disease to the pest or compete or kill them.

Some examples of Microbial bio-control :

  • Bacillus thuringiensis (Bt) : It is used to get rid of butterfly, caterpillars.
  • Trichoderma species : Effective bio-control agents against soil borne fungal plant pathogens.

Four groups of biocontrol agents are known. They are bacteria, fungi, viruses and protozoans.

Microbial Pesticides and their host :

Microbial Pesticides and their host :

The corelation is depicted as per the following table :

Pathogen Host
Bacteria: Bacillus thuringiensis (Bt), B. papilliae and B.lentimorbus Caterpillars, cabbage worm, adult beetle,etc.
Fungi: Beavueria bassiana, Entomophthora. pallidaroseum, and Zoopthora radicans Aphid crocci, A. unguiculata, mealy bugs, mites, white flies etc
Protozoans: Nosema lacustae Grasshopper, caterpillars, crickets
Viruses: Nucleopolyhedrovirus (NPV) and Granulovirus (GV) Caterpillars and Gypsy moth, ants, wasps and beetles.


Bioherbicides : They kill the weeds which compete with the main crop in the farm - land for water, space, minerals, light, air, etc. and also act as collateral hosts for several pathogens.

Pathogenic fungi as mycoherbicides :

  • Phytophthora palmivora - controls milk weed in orchards.
  • Alternaria crassa — controls water hyacinth.
  • Fusarium spp. - control most of the weeds.

Bacterial pathogen as herbicides :

  • Pseudgmonas spp. - attacks several weeds
  • Xanthomonas spp. - attacks several weeds
  • Agrobacterium spp. — attacks several weeds

Insects as herbicides :

  • Tyrea moth — controls the weed Senecio jacobeac
  • Cactoblastis cactorum — controls cacti weeds.

Role of Microbes as Biofertilizers:

Fertilizers are nutrients which are necessary for the growth of plants and thus for the productivity of cultivated plants. When they are applied to plants, in soil or in composting pits, soil fertility increases. Biofertilizers are cost effective and eco-friendly.

Classification of Biofertilizers :

  • On the basis of nature or group of organisms, biofertilizers are classified as bacterial fertilizers and fungal fertilizers.
  • On the basis of function, bacterial fertilizers are further grouped as nitrogen fixing, phosphate solubalizing and compost making biofertilizers.
  • Cynobacterial biofertilizers, on the basis of function, are nitrogen fixing type.
  • Fungal biofertilizers include mycorrhizal fungi. On the basis of function, they are classified as ectomycorrhizae and endomycorrhizae.

Bacterial biofertilizers :

Bacterial biofertilizers :

Nitrogen fixing bacterial biofertilizers:

  • They convert atmospheric nitrogen into compounds of nitrogen like ammonia, nitrites and nitrates.
  • The nitrogen fixing bacteria Rhizobium forms symbiotic association with roots of leguminous plants.
  • Free living nitrogen fixing bacteria are Azotobacter and Azospirillum.

Phosphate solubilizing biofertilizers :

  • They are the bacteria which solubilize the insoluble inorganic phosphate compound. e.g. Pseudomonas striata, Bacillus polymyxa, Agrobacterium, Microccocus, Aspergillus spp., etc.
  • Bacteria are also involved in composting.

Compost making biofertilizers :

  • In the composting process microorganisms break down organic matter into dark rich compost or humus.
  • Microorganisms found in active compost : Bacteria, fungi, actinobacteria, protozoa and rotifers.

Cyanobacterial biofertilizers :

  • They are nitrogen fixing biofertilizers.
  • Heterocysts are the site of nitrogen fixation.
  • Free living cyanobacteria are Anabaena. Nostoc, Tolypothrix, Plectonema, Oscillatoria.
  • Anabaena and Nostoc have symbiotic relationship with lichens
  • Anabaena is also syrnbiotically associated with Azolla and Cycas.

Fungal biofertilizers :

Mycorrhiza is a fungus which forms symbiotic association with the rhizomes and root of higher plants occurring in thick humid forests.

Two types of mycorrhiza :

  • Ectomycorrhizae : Mycelium of these fungi form mantle on the surface of the roots.
  • Endomycorrhizae : They grow in between and within the cortical cells of roots.


Benefits of Mycorrhiza :

Benefits of Mycorrhiza :

  • Selective absorption of P, Zn, Cu, Ca, N, Mn, Br and Fe.
  • Enhance water uptake.
  • Induce growth by secreting hormones.
  • Offer protection to host plant from other microbes, by secreting antibiotics.
  • Nowadays, mycorrhiza are classified into 8 different types : Ectomycorrhizae, Eudomycorrhizae, Ectendo mycorrhizae, Orchidaceous mycorrhizae, Ericoid mycorrhizae, Arbutoid mycorrhizae, Monotrapoid mycorrhizae and Ophioglossoid mycprrhizae.


Biofertilizer microorganisms

  • Rhizobia : Nitrogen fixing bacteria in root nodules of leguminous plants. e.g. R. leguminosarum is specific to pea and R. phaseoli is specific to beans.
  • Azotobacter : Free living, nitrogen fixing bacterium associated with roots of grasses and certain plants.
  • Azospirillum : Free living, aerobic nitrogen fixing bacterium associated with roots of corn, wheat and jowar.
  • Anabaena : Filamentous nitrogen fixing cyanobacteria that forms symbiotic relationships with certain plants, such as the coralloid roots of Cycas and Anthoceros thallus. It has Heterocysts (Specialized colourless cells which are the sites for nitrogen fixation). It also fixes nitrogen in free living conditions.
  • Azolla : A free-floating water fern. Anabaena present in the dorsal leaf lobe fixes nitrogen.

Benefits of Biofertilizers :

Benefits of Biofertilizers :

  • Low cost and can be used by marginal farmers.
  • Free from pollution hazards.
  • Increase soil fertility.
  • BGA secret growth promoting substances, organic acids, proteins and vitamins.
  • Azotobacter supply nitrogen and antibiotics in the soil.
  • Biofertilizers increase physico-chemical properties of soil-like texture, structure, pH, water holding capacity of soil by providing nutrients and organic matter.


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