Question

Name two bacteria which are used as biofertilizer.

Answer 1

Hint:- Bacteria are single-celled unicellular organisms and are classified under the domain Prokaryote because they lack membrane-bound organelles like those found in eukaryotes. Although they are all microscopic organisms and cannot be seen with naked eyes that can be found in various environments in nature, bacteria widely vary in size, shape, and arrangement.

Complete answer:
Bacteria are specialised to perform many functions such as they acts as:-
Saprophytic bacteria : They are free living bacteria, obtaining nourishment from organic remains such as dead animals, animal excreta, fallen leaves, decaying vegetables, fruits, bread and other products of animal and plant origin. These bacteria secrete digestive enzymes into the substrate and the complex insoluble substances are converted into simple soluble compounds like water, hydrogen sulphide, ammonia, $\mathop {CO}\nolimits_2$, etc. Some of the simple substances are absorbed and accumulated by the bacteria, whereas the others are added to the soil and atmosphere to complete nature's material cycle.
Symbiotic bacteria ( as biofertilizers) : They are mainly Gram negative type. A most common example of symbiotic bacteria is Rhizobium leguminosarum, that remains associated with roots of leguminous plants. They are helpful in fixing atmospheric nitrogen as ammonia, inside the nodule only and not in free state. However, some bacteria like Azotobacter, Beijerinckia, Klebsiella are free living, aerobic that respire in the presence of oxygen and capable of nitrogen fixation in free state, enriching the soil. Clostridium is anaerobic $\mathop N\nolimits_2$, fixing bacteria. These are used as biofertilizers.
Parasitic bacteria : These bacteria draw nourishment and obtain special organic compounds required for growth from living organisms, either plants or animals, called hosts. The disease bacteria which causes disease are termed pathogenic and the ones not causing any disease are termed as non-pathogenic.
as biopesticides: bio pesticides are substances that are used to increase soil fertility and to increase crop production but they are produced from natural resources such as plants and animals. The first bacteria to be used as biopesticide is Bacillus thuringiensis.

So, our required answer is Rhizobium and Anabaena

Note:- Bio fertilizers increase soil fertility so these bacteria also increase soil fertility. Several types of symbiotic biological nitrogen-fixing associations are known. The most preferable amongst them is the legume-bacteria relationship. Species of rod-shaped Rhizobium live symbiotically in association within the roots of several leguminous plants such as alfalfa, sweet clover, sweet pea, lentils, garden pea, broad bean, clover bean, etc.