Maharashtra Board Class 10 Science Part 2 Chapter 7 Introduction to Microbiology PDF Download

7. Introduction To Microbiology

Applied Microbiology

Industrial Microbiology

Products

1. Which different microbes are useful to us?

2. Which different products can be produced with the help of microbes?

Applied Microbiology

Branch of biology in which study of the enzymes related to some prokaryotes and eukaryotic microbes, proteins, applied genetics, molecular biology, etc. is performed; is called as applied microbiology. This study is used for the society and various products like food and medicines are produced on large scale with the help of microorganisms.

Industrial Microbiology

This science is related to commercial use of microbes in which various economic, social and environment related processes and products are included. Various microbial processes useful for this purpose are carried out.

Industrial Microbiology: Main Features

A. Various productions with the help of fermentation process. Ex. Bread, cheese, wine, row material for chemicals, enzymes, nutrients, medicines, etc.

B. Use of microbes for garbage management and pollution control.

Teacher's Note

Microbes help us make yoghurt, cheese, and many other foods. In India, we use lactobacilli bacteria to turn milk into dahi (yoghurt), which is eaten every day in many homes.

Exam Trick

Remember: Applied microbiology = using microbes to make things. Industrial microbiology = using microbes on a big scale to make money. Think of it like the difference between making dahi at home and making it in a factory.

Points to Remember

Applied microbiology studies enzymes and uses microbes to make food and medicines.
Industrial microbiology uses microbes in large amounts for business and money.
Microbes make cheese, butter, yoghurt, and bread through fermentation.
Bacteria and fungi help us create useful products.
These processes are easy to learn and see in daily life.

We use the fermentation process while conversion of milk into yoghurt. Which microbes are useful for this process?

Products

A. Dairy Products

Since ancient days, milk is converted into various products for its preservation purpose. Ex. Cheese, butter, cream, kefir, yoghurt, etc. Water content and acidity of the milk changes during formation of these products and texture, taste and flavour is improved.

These processes are performed on large scale with more skill. For production of most of the milk products, bacteria in milk itself are used; only cheese is produced with the help of fungi. Basic process for production of yoghurt, cheese and cream is same. Milk is pasteurized at the beginning to destroy unwanted microbes. It is then fermented with the help of lactobacilli. In this process, lactose sugar of the milk is converted into lactic acid and milk proteins are coagulated with the help of lactic acid. Besides, compounds with taste and flavour are also formed. Ex. Diacetyl has the flavour of butter.

Teacher's Note

Dairy products like paneer, dahi, and lassi are made using bacteria and fungi. In India, every home makes or buys these products because they are healthy and taste good.

Exam Trick

Remember: Lactobacilli = good bacteria that turn milk sour and thick. Lactose = milk sugar that bacteria eat and turn into lactic acid.

Points to Remember

Milk is boiled and cooled before adding bacteria.
Lactobacilli bacteria turn milk into yoghurt and cheese.
Lactic acid makes milk thick and gives it a sour taste.
Water is removed from milk to make cheese harder.
Fungi are used only for cheese, not for other dairy products.

2. Yoghurt Products

Yoghurt is a milk product produced with the help of lactobacilli (inoculant). For maintaining the protein content, condensed milk powder is mixed with milk to be fermented for industrial production of yoghurt. Milk is boiled and once it cools to warm temperature, bacterial strains of Streptococcus thermophilus and Lactobacillus delbrueckii are added to it in 1:1 proportion. Lactic acid is formed due to Streptococcus that makes the proteins to gel out that gives dense consistency to the yoghurt.

Acetaldehyde like compounds are formed due to lactobacilli that gives characteristic taste to the yoghurt. Now a day, various fruit juices are mixed with yoghurt to impart different flavours. Ex. Strawberry yoghurt, banana yoghurt, etc. Shelf life of yoghurt and its probiotic properties can be improved by pasteurization.

3. Butter

Two types of butter like sweet cream and cultured are produced on large scale. Microbes are used for production of cultured variety.

4. Cheese Production

Cheese is produced on large scale from the abundantly available cow milk all over the world. First, chemical and microbiological tests of milk are performed. Some colours and microbes like Lactobacillus lactis, Lactobacillus cremoris, and Streptococcus thermophilus are mixed with milk. It imparts sourness to the milk. After this, to impart the dense texture, whey (water in yoghurt) needs to be removed.

An enzyme, rennet obtained from alimentary canal of cattle was being traditionally used earlier. However, an enzyme protease obtained from fungi is used at present to produce vegetarian cheese. The whey is separated from yoghurt (which has some other uses). Then, process of production of cheese is started through steps like cutting the solid yoghurt into pieces, washing, rubbing, salting, and mixing of essential microbes, pigments and flavours. Then, cheese is pressed and cut in to pieces and stored for ripening.

1. Which different types of cheese are used in western food like pizza, burger, sandwich, etc?

2. What is difference between those types of cheese?

During industrial production of milk products, strict cleanliness and sterilization is essential as bacteria can be attacked by viruses. Hence, virus-resistant varieties of bacteria are developed. Recently, use of mutant varieties of bacteria has been increased. Artificially, some strains are developed that will help to avoid unnecessary steps / materials.

Freshly prepared cheese is always soft e.g. cottage cheese, cream cheese, mozzarella cheese. On storing for 3 to 12 months, semi-hard cheddar cheese is formed whereas after ripening for 12 – 18 months, very hard cheese called parmesan cheese is formed.

Teacher's Note

Paneer is a fresh cheese made in Indian kitchens. It is soft and can be made at home by adding lemon juice or vinegar to hot milk. This shows how simple fermentation works.

Exam Trick

Remember: Fresh cheese = soft (paneer, mozzarella). Old cheese = hard (parmesan). The longer you keep cheese, the harder it becomes.

Points to Remember

Streptococcus and Lactobacillus bacteria are used to make yoghurt and cheese.
Milk must be boiled and cooled before adding bacteria.
Whey is water removed from yoghurt to make cheese thick.
Fungi are used to make the enzyme that curdles milk.
Hard cheese takes 12 to 18 months to make, soft cheese is ready in days.

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