(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.

Single cell protein refers to edible unicellular microorganisms like Spirulina. Protein extracts from pure or mixed cultures of algae, yeasts, fungi or bacteria may be used as ingredient or as a substitute for protein rich foods and is suitable for human consumption or as animal feed.

(i) Protecting soil quality using organic materials and encouraging biological activity.
(ii) Indirect provision of crop nutrients using soil microorganisms.
(iii) Nitrogen fixation in soils using legumes.
(iv) Weed and pest control based on methods like crop rotation, biological diversity, natural predators, organic manures and suitable chemical, thermal and biological interventions.

(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.

1. Milk is converted into curd with the help of bacteria like Lactobacillus acidophilus Lactobacillus lactis and Streptococcus lactis are commonly called Lactic Acid Bacteria (LAB).
2. The LAB bacteria grow in milk and convert it into curd, thereby digesting the milk protein casein.
3. A small amount of curd added to fresh milk as a starter or inoculum contains millions of Lactobacilli, which under suitable temperature \(\left(\leq 40^{\circ} \mathrm{C}\right)\) multiply and convert milk into curd by fermentation.
4. Curd is more nutritious than milk as it contains a number of organic acids and vitamins.

Biodiesel is a fuel made from vegetable oils, fats or greases. Biodiesel fuel can be used in diesel engines without altering the engine. Pure biodiesel is non-toxic, biodegradable and produces lower level of air pollutants than petroleum-based diesel fuel.

Antibiotics are chemical substances produced by microorganisms which can kill or retard the growth of other disease causing microbes even in low concentration. Antibiotic means ''against life".

(i) Biogas is a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen.
(ii) The slurry is drained through another outlet and is used as fertilizer.
(iii) Biogas is used for cooking and lighting.

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).

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.

Pencillin

Lecunostoc mesenteroides

Acetaldehyde.

Lactic acid bacteria