how do microorganisms overcome the unfavourable conditions?
The microorganisms survive the unfavourable conditions either by producing spores or developing a cyst.
In response to harsh conditions, some microbes like bacteria will often form spores, which are a condensed and protected collection of the cells genetic material that is capable of re-growth upon introduction into a suitable environment. The spore is only protected content of cell not the living cell.
Some microorganisms on exposure to extreme conditions like high temperature, scarcity of food etc transform themselves into a cyst. Cysts are the living cells covered with tough shells for protection in harsh conditions, cysts remain in dormant condition till the arrival of favourable conditions.
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Microorganisms were survive by defence mechanism :-
Defense mechanism in Microbes:
Bacteria and other microorganisms have various types of structural and physiological or biochemical means for defense against their enemies and adverse situations. A large number of bacteria and fungi produce digestive enzymes and toxic chemicals such as antibiotics and antimicrobial compounds. These compounds can kill or damage the cells of organisms in which they are in contact.
Many bacteria and other microorganisms are capable of producing capsules.
The phagocytic cells cannot engulf and destroy the capsulated bacterial cells. Phagocytes such as macrophages and neutrophils can easily engulf the noncapsulated bacterial cells and destroy them easily.
During unfavorable conditions, a large number of bacteria can be changed into spores, known as endospores. The cytoplasm of the cell is detached from the cell wall and changed into a spore in the middle of the cell. The spore has a very thick covering, and since it is formed within the cell, it is called an endospore. Endospores are highly resistant to heat, UV-radiations, and chemicals and antibiotics. Even though the formations of endospores are a mechanism to overcome the unfavorable conditions, the formation of such endospores can be considered a defense mechanism.