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.

(a) Antibiosis: Property of antibiotics to kill microbes.
(b) Superbugs: Bacterial strains gained resistance against antibiotics.

Broad-spectrum antibiotics act against a wide range of disease-causing bacteria.
Narrow-spectrum antibiotics are active against a selected group of bacterial types.

Yogurt, Paneer, Curd, Idly batter, Bread dough

Beverages, antibiotics, organic acids, amino acids, vitamins, biofuels, single cell protein, enzymes, steroids; vaccines, pharmaceutical drugs.

(a) The flavor in yogurt is due to acetaldehyde formation.
(b) Large holes in Swiss Cheese is due to more CO₂ production by Propionibacterium shermanii

They are genes present in the bacterium Bacillus thuringiensis and code for crystal proteins called Delta-endotoxin which are toxic to certain Insect pests. The Bacteria is used to produce genetically engineered insect resistant plants.

The use of a microbes or other biological agents to control a specific pest is called a biopesticide. Biopesticides are used to control insect pests. The lady bird beetle and dragonflies are useful to control aphids and mosquito larvae respectively.

\(\underset { (Glucose) }{ { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 } } \overset { Yeast }{ \underset { Fermentation }{ \longrightarrow } } { 2C }_{ 2 }{ H }_{ 5 }+2{ CO }_{ 2 }\uparrow \)

World biofuel day is observed. every year on 10th August of renewable bio- fuels as an alternative to conventional non-renewable fossil fuels. This day also highlights the various efforts taken by the Government in the biofuel sector.

The "Pasteur effect" is the inhibiting effect of oxygen on the fermentation process.

"superbug "is a term used to describe strains of bacteria that are resistant to the majority of antibiotics commonly used today.

Antibiotic resistance occurs when bacteria develop the ability to defeat the drug designed to kill or inhibit their growth. Thus they multiply and antibiotics cannot light them.

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).