State two economically important uses of

(a) Heterotrophic bacteria:

(i) Saprotrophic bacteria act as natural scavengers as they decompose the dead bodies, organic wastes and release raw materials leading to reuse of organic matter. They also help in sewage disposal, manure production etc.

(ii) Symbiotic bacteria help in atmospheric nitrogen fixation.

(iii) Some bacteria are employed in the production of a number of industrial products like lactic acid, curd, cheese, butter, vinegar etc. iv. Some bacteria are used in the preparation of serum, vaccines, vitamins, enzymes, antibiotics, etc. e.g., Pseudomonas, Xanthomonas, etc.

(b) Archaebacteria:

(i) Archaebacteria are employed in the production of gobar gas from dung and sewage and in ruminants, they cause fermentation of cellulose.

(ii) Some Archaebacteria live in the guts of ruminants such as cows and buffaloes and help in their digestion.