Colonies of bacteria that secrete a sticky outer coat that is hard to penetrate are called:

A. prions
B. viruses
C. protozoa
D. biofilms



Answer :

Final answer:

Biofilms are robust bacterial communities resistant to sterilization methods due to their sticky outer coatings.


Explanation:

Biofilms are complex colonies of bacteria held together in a sticky matrix that makes them resistant to antibiotics. They have protective coatings that exclude many sterilization methods, making them hardy and difficult to destroy.


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