The habitat of $E. coli$ is

In bacteria,sexual conjugation is promoted by

Which type of organism are $PPLO$?

$A$ few organisms are known to grow and multiply at temperatures of $100-105^{\circ}C$. They belong to:

Which bacteria are responsible for the digestion of cellulose in the food of ruminant animals?

In the vast marine ecosystem, certain seas develop red colouration. This red colour is due to the presence of a large population of which one of the following organisms?