Useful & Harmful micro-organisms

1. BY…
SHARIYAM ALI

2. Microbes??A microorganism, especially a bacterium causing
disease or fermentation
1) Lactobacilli
2) Rhizobium
3) Yeast
Useful:

3. Lactobacilli
 Milk
 Sugar Lactose-- Lactic Acid
pH decreases
Coagulation of milk
Formation of yoghurt
Yoghurt- Sour taste,low pH therefore
harmful microbes destroyed
Probiotic”
Yakult, Yoghurt etc
Lactobacilli are added to them

4. Rhizobium : Symbiotic bacteria

5. Role and importance of rhizobium
 Rhizobia living in root nodules
 supply nitrates, nitrites and amino acids to that plant
and in exchange get energy in the form of
carbohydrates from it.
 Symbiosis
 Host
 Beans and pulses are rich in proteins due to the
nitrogenous compounds made available by rhizobia.

6. Yeast
 Bring ‘active dry yeast’ from the market.
 Mix a spoonful of yeast, two spoonfuls sugar with a
sufficient quantity of lukewarm water in a bottle.
 Fix a colourless, transparent balloon on the mouth of
that bottle.
 After 10 minutes the balloon inflates
 Mix limewater with the gas accumulated in the balloon.
 Collect that limewater in a beaker and observe it.
 Limewater turns milky
 Presence of CO2 is Confirmed

7. Buudding
Budding
unicellular fungus
heterotrophic
Sugar to CO2
Fermentation

8. How is bread made ?
 Find out how to use the solution prepared in the above
experiment, to make bread.
 Follow the recipe and make the bread.
 Find out and note down the reasons why the dough
rises and makes the bread spongy.

9. THANK YOU 