Lactic Acid bacteria (LAB) are the probiotics that check the growth of pathogenic microbes in the stomach and other digestive parts

Curd is more nutritious than milk Since it contains a number of organic acids and vitamins

The use of naturally occurring or genetically engineered microorganisms to reduce or degrade pollutants is called bioremediation. Bioremediation is less expensive and more sustainable than other re-mediations available

lt is an enzyme and can be used to separate milk into solid curds for cheese making

Lipases are used in detergent formulations and are used for removing oily stains from the laundry.

Zymology an applied science which deals with the biochemical process of fermentation and its practical uses.

Antibiosis is the property of antibiotics to kill microorganisms.

Probiotics are live microorganisms intended to provide health benefits when consumed, generally by improving or restoring the gut flora Lactic acid bacteria in milk.

BOD stands for Biological Oxygen Demand. BOD refers to the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria. The greater the BOD of the waste water, the more is its polluting potential.

Enzymes - Produced from Yeast (Saccharomyces cerevisiae) and bacteria
(i) Eg: pectinase, protease and cellulase - Bottled juices are clarified.
(ii) Rennet - separate milk into solid curds for cheese making.
(iii) Streptokinase (from Streptococcus) - Clot busier - (removing clots from the blood vessels of patients who have undergone myocardial infarction patients).
Cycloporin 'A' - Immuno suppressant used in organ transplantation (produced from the fungus Trichoderma Polysporum).

In some parts of South India, a traditional drink called pathaneer is obtained from fermenting sap of palms and coconut trees. A common source is tapping of unopened spadices of coconut. It is a refreshing drink, which on boiling produces jaggery or palm sugar. When pathaneer is left undisturbed for a few hours it gets fermented to form toddy with the help of naturally occurring yeast, to form a beverage that contains 4 percent alcohol. After 24 hours toddy becomes unpalatable and is used for the production of vinegar

(a) Alexander Fleming
(b) Earnest Chain
(c) Howard Florey

Organic farming is a technique which involves cultivation of plants and rearing of animals in natural ways. It involves use of biological materials, avoiding synthetic substances to maintain soil fertility and ecological balance thereby minimizing pollution wastage. g. Use of biofertilizers.

UV is an ideal disinfectant for wastewater since it does not alter the water quality - except for inactivating microorganisms. UV is a chemical free process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia

Cyclosporin A, an immunosuppressant used in organ transplantation is produced from the fungus Trichoderma polysporum. It is also used for its anti-inflammatory, anti-fungal and antiparasitic properties.

(i) It is an antibiotic produced by the fungus Penicillium notatum and Penicillium chrysogenum.
(ii) It is bactericidal in action and inhibits the synthesis of the bacterial cell wall.
(iii) It is the queen of drugs and was discovered by Alexander Flemming.

The dough used in bread making is fermented by Saccharomyces cerevisiae (Baker's Yeast). Fermentation of glucose mainly forms ethyl alcohol and carbon-dioxide which is responsible for leavening of dough. When leavened dough is baked, both carbon-dioxide and ethyl alcohol evaporate making the bread porous and soft

(i) Bio-fertilizers are formulation of living microorganisms that enrich the nutrient quality of the soil. They increase physico - chemical properties of soils such as soil structure, texture, water holding capacity, cation exchange capacity and pH by providing several nutrients and sufficient organic matter.
(ii) The main sources of bio-fertilizers are bacteria, fungi and cyanobacteria. Rhizobium is a example for symbiotic nitrogen fixing bacteria. This bacterium infects the root nodules of leguminous plants and fixes atmospheric nitrogen into organic forms. Azospirillum and Azotobacter are free living bacteria that fix atmospheric nitrogen and enrich the nitrogen content of soil.
(iii) A symbiotic association between a fungus and the roots of the plants is called mycorrhiza. The fungal symbiont in these associations absorbs the phosphorus from soil and transfers to the plant. Plants having such association show other benefits such as resistance to root-borne pathogens, tolerance to salinity, drought, enhances plant growth and developments. For example, genus Glomus form mycorrhiza.
(iv) Cyanobacteria (or) blue green algae (BGA) are prokaryotic free-living organisms which can fix nitrogen. Oscillatoria, Nostoc, Anabaena, Tolypothrix are well known nitrogen fixing cyanobacteria. In water logged paddy fields Cyanobacteria multiply and fix molecular nitrogen. Cyanobacteria secrete growth promoting substances like indole-3-acetic acid, indole-3-butyric acid, naphthalene acetic acid, amino acids, proteins, vitamins which promotes plant growth and production.
(v) Biofertilizers are commonly used in organic farming methods.
(vi) This process involves the use of biological materials, avoiding synthetic substances to maintain soil fertility and ecological balance thereby minimizing pollution and wastage.

(i) Bacillus thuringiensis is a soil dwelling bacterium which is commonly used as a biopesticide and contains a toxin called cry toxin. Scientists have introduced this toxin producing genes into plants and have raised genetically engineered insect resistant plants. Eg. Bt-cotton.
(ii) When the insects ingest the toxin crystals their alkaline digestive tract denatures the insoluble crystals making them soluble. The cry toxin then gets inserted into the gut cell membrane and paralyzes the digestive tract. The insect then stops eating and starves to death.

Aerobic microbes degrade the pollutants in the presence of oxygen. They mainly degrade pesticides and hydrocarbons. Pseudomonas putida is a genetically engineered microorganism (GEM). Ananda Mohan Chakrabarty obtained patent for this recombinant bacterial strain. It is multiplasmid hydrocarbon-degrading bacterium which can digest the hydrocarbons in the oil spills.
Nitrosomonas europaea is also capable of degrading benzene and a variety of halogenated organic compounds including trichloroethylene and vinyl chloride. Ideonella sakaiensis is currently tried for recycling of PET plastics. These bacteria use PETase and MHETase enzymes to breakdown PET plastic into terephthalic acid and ethylene glycol.
Anaerobic microbes degrade the pollutants in the absence of oxygen. Dechloromonas aromatica has the ability to degrade benzene anaerobically and to oxidize toluene and xylene. Phanerochaete chrysosporium an anaerobic fungus exhibits strong potential for bioremediation of pesticides, polyaromatic hydrocarbons, dyes, trinitrotoluene, cyanides, carbon tetrachloride, etc., Dehalococcoides species are responsible for anaerobic bioremediation of toxic trichloroethene to nontoxic ethane. Pestalotiopsis microspora is a species of endophytic fungus capable of breaking down and digesting polyurethane. This makes the fungus a potential candidate for bioremediation projects involving large quantities of plastics.

Sewage treatment is usually performed in the following three stages

Primary treatment: Primary treatment involves the physical removal of solid and particulate organic and inorganic materials from the sewage through filtration and sedimentation. Floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.
Secondary treatment or biological treatment: The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floc (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. The greater the BOD of the waste water more is its polluting potential. Once the BOD of sewage water is reduced significantly, the effluent is then passed into a settling tank where the bacterial "floes" are allowed to sediment. This sediment is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, the bacteria which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and CO₂. These gases form biogas and can be used as a source of energy.
Tertiary treatment: Tertiary treatment is the final process that improves the quality of the waste water before it is reused, recycled or released into natural water bodies. This treatment removes the remaining inorganic compounds and substances, such as nitrogen and phosphorus. UV is an ideal disinfectant for wastewater since it does not alter the water quality - except for inactivating microorganisms. UV is a chemical free process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.

Microbes used for production of chemicals like organic acids and enzymes. Examples of organic acid producers are Aspergillus niger for citric acid, Acetobacter aceti for acetic acid, Rhizopus oryzae for fumaric acid, Clostridium butyricum for butyric acid and Lactobacillus for lactic acid.
Yeast (Saccharomyces cerevisiae) and bacteria are used for commercial production of enzymes. Lipases are used in detergent formulations and are used for removing oily stains from the laundry. Bottled juices are clarified by the use of pectinase, protease, and cellulase. Rennet can also be used to separate milk into solid curds for cheese making. Streptokinase produced by the bacterium Streptococcus and genetically engineered Streptococci are used as "clot buster" for removing clots from the blood. vessels of patients who have undergone myocardial infarction.
Cyclosporin A, an immunosuppressant used in organ transplantation is produced from the fungus Trichoderma polysporum. It is also used for its anti-inflammatory, anti-fungal, and anti-parasitic properties. Statins produced by the yeast Monascus purpureus have been used to lower blood cholesterol levels. It acts by competitively inhibiting the enzyme responsible for the synthesis of cholesterol. Recombinant human insulin has been produced predominantly using E. coli and Saccharomyces cerevisiae for therapeutic use in human.

(i) Biogas is a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced from raw materials such as agricultural wastes, manure, municipal wastes, plant material, sewage, food waste, etc.,
(ii) The excreta of cattle called dung is commonly called "Gobar'. Gobar gas is generated by the anaerobic decomposition of cattle dung. It consists of methane, CO₂ with some hydrogen, nitrogen and other gases in trace amounts.
(iii) In a biogas plant, anaerobic digestion is carried out in an air tight cylindrical tank known as digester (Fig.). It is made up of concrete bricks and cement or steel. Bio-wastes are collected and slurry of dung is fed into this digester. It has a side opening into which organic materials for digestion are incorporated for microbial activity. Anaerobic digestion is accomplished in three stages: solubilisation, acidogenesis and methanogenisis. The outlet is connected to a pipe to supply biogas. The slurry is drained through another outlet and is used as fertilizer. Biogas is used for cooking and lighting.

Sewage treatment is usually performed in the following three stages:
(I) Primary treatment:
(a) Primary treatment involves the physical removal of solid and particulate organic and inorganic materials from the sewage through filtration and sedimentation.
(b) Floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation.
(c) All solids that settle form the primary sludge and the supernatant forms the effluerit and is taken for secondary treatment.
(II) Secondary treatment or biological treatment:
(a) The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it.
(b) This allows vigorous growth of useful aerobic microbes into floc (masses of bacteria associated with fungal filaments to form mesh like structures). Which consume the organic matter in the effluent.
(c) This significantly reduces the BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. The greater the BOD of the waste water more is its polluting potential.
(d) Once the BOD of sewage water is reduced Significantly, the effluent is then passed into a settling tank where the bacterial "flocs" are allowed to sediment. Which is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum.
(e) The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, the bacteria which grow anaerobically, digest the bacteria and the fungi in the sludge. During digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and CO₂ Which form biogas and can be used as a source of energy.
(III) Tertiary treatment
(a) Tertiary treatment is the final process that improves the quality of the waste water before it is reused, recycled or released into natural water bodies.
(b) This treatment removes the remaining inorganic compounds and substances, such as nitrogen and phosphorus.
(c) UV is an ideal disinfectant for wastewater since it does not alter the water quality - except for inactivating microorganisms. UV is a chemical-free process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.

S. No	Primary Treatment	Secondary Treatment
i.	It involves the physical removal of solid, and particulate organic and inorganic materials fro the sewage through filtration and sedimentation. The supernatant is the effluent which is taken for secondary treatment.	The process takes place in large aeration tanks with vigorous growth of microbes. The organisms break down the organic matter and reduces the Biological oxygen demand it is further passed into a setting tank where are bacterial 'flocs' sediment to form the activated sludge.
ii.	It is a total physical process.	It is a biological process.
iii.	The solid waste is mainly removed.	The dissolved organic waste is removed by this process by aerobic and anaerobic means.
iv	It is a similar process.	It is more time consuming and a major part of sewage treatment.
v.	No by products are produced	Biogas production occurs.

(a) Brewer's yeast:
(i) Saccharomyces cerevisiae commonly called brewer's yeast.
(ii) It is used for fermenting malted cereals and fruit juices to produce various alcoholic beverages.
(iii) Wine is made from the fermentation of grape juice.
(iv) Grape juice is fermented by various strains  of Saccharomyces cerevisiae into alcohol.
(v) Beer is produced from germinated barley malt grain by Saccharowces carlsbergensis or Saccharomyces cerevisiae.
(vi) Rum is made from fermented sugarcane or molasses or directly from sugarcane juice by Saccharomyces cerevisiae.
(vii) Whisky is a type of distilled alcoholic beverage made from fermented grain mash.
(viii) It is the major producer- of ethanol (C₂H₅OH)
(ix) It is used as industrial alcohol and also used for laboratory and fuel purposes.
(x) It is used for commercial production of enzymes.
(b) Ideonella sakaiensis:
(i) Ideonella sakaiensis is currently tried for recycling of PET plastics.
(ii) These bacteria use PETase and MHETase enzymes to breakdown PET plastic into terephthalic acid and ethylene glycol.
(c) Microbial fuel cells (MFC)
1. Microbial fuel cells work by allowing bacteria to oxidize and reduce organic molecules.
2. Bactedal respiration is basically one big redox reaction in which electrons are being moved around.
3. A MFC consists of an anode and a cathode separated by a proton exchange membrane.
4. Microbes at the anode oxidize the organic fuel generating protons which pass through the membrane to the cathode and the electrons pass through the anode to the external circuit to generate current.