State two economically important uses of:
(a) Heterotrophic bacteria
(b) Archaebacteria

Explanation

Heterophic bacteria : (i) They are helpful in making curd from milk, (ii) They are also useful in production of antibiotics, fixing nitrogen in legume roots.
(b) Archaebacteria : (i) Methanogens are present in the guts of several ruminant animals like cows and buffaloes and they are responsible for the production of methane (biogas) from dung of such animals, (ii) Due to different cell wall structure than bacteria, they are able to tolerate extreme conditions.