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Microbes in Human Welfare - Microbes in Household Products

Grade 12CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Microorganisms like LactobacillusLactobacillus and others commonly called Lactic Acid Bacteria (LAB) grow in milk and convert it to curd.

During growth, LAB produce acids that coagulate and partially digest the milk proteins (casein).

Curd is more nutritional than milk as it contains an increased amount of Vitamin B12B_{12}.

LAB play a beneficial role in checking disease-causing microbes in the human stomach.

The dough used for making foods like dosa and idli is fermented by bacteria, resulting in a puffed-up appearance due to the production of CO2CO_2 gas.

Baker's yeast (SaccharomycesSaccharomyces cerevisiaecerevisiae) is used to ferment dough for making bread.

'Toddy', a traditional drink in parts of southern India, is made by fermenting sap from palms.

Microbes are used to ferment fish, soybean, and bamboo shoots to make food.

Large holes in 'Swiss cheese' are due to the production of a large amount of CO2CO_2 by the bacterium PropionibacteriumPropionibacterium sharmaniisharmanii.

'Roquefort cheese' is ripened by growing a specific fungus, PenicilliumPenicillium roquefortiroqueforti, on them to give them a particular flavor.

📐Formulae

C12H22O11(Lactose)+H2OLAB4CH3CH(OH)COOH(Lactic Acid)C_{12}H_{22}O_{11} (Lactose) + H_{2}O \xrightarrow{LAB} 4CH_{3}CH(OH)COOH (Lactic\ Acid)

C6H12O6(Glucose)Yeast2C2H5OH(Ethanol)+2CO2+EnergyC_{6}H_{12}O_{6} (Glucose) \xrightarrow{Yeast} 2C_{2}H_{5}OH (Ethanol) + 2CO_{2} + Energy

💡Examples

Problem 1:

Name the bacterium responsible for the large holes in Swiss cheese and identify the gas produced.

Solution:

The bacterium is PropionibacteriumPropionibacterium sharmaniisharmanii and the gas produced is CO2CO_{2}.

Explanation:

During the fermentation process, PropionibacteriumPropionibacterium sharmaniisharmanii releases a significant volume of CO2CO_{2}, which gets trapped in the cheese, forming large characteristic holes.

Problem 2:

How does the nutritional quality of milk improve when it is converted into curd?

Solution:

The nutritional quality improves due to the increase in Vitamin B12B_{12} content.

Explanation:

Lactic Acid Bacteria (LAB) not only convert lactose into lactic acid but also synthesize Vitamin B12B_{12} during the process of curdling milk.

Microbes in Household Products - Revision Notes & Key Diagrams | CBSE Class 12 Biology