Question

Which of the following is symbiotic bacteria?
(a)Rhizobium
(b)Azotobacter
(c)Clostridium
(d)Streptomyces

Answer 1

They are a genus of bacteria related to the formation of root nodules on plants. They’re an important source of nitrogen to agricultural soils including those in arid regions. They convert nitrogen into ammonia.

Complete answer:
Atmospheric nitrogen isn't available to the plants. Nitrogen-fixing bacteria convert atmospheric nitrogen into ammonium compounds and make them available to the plants. There are two sorts of bacteria, free-living and symbiotic. The symbiotic nitrogen-fixing bacteria including Rhizobium, have symbiotic associations with pea plants (alfalfa, beans, clovers, peas, soybeans) to help in the organic process. These bacteria sleep in the roots of leguminous plants (e.g., pea and beans plants), and using certain sorts of enzymes, they assist in fixing nitrogen within the soil. During this organic process, they convert the non-absorbable nitrogen form into a usable form. This type of nitrogen gets dissolved within the soil, and plants absorb the modified nitrogen from the soil. This is often the rationale behind farmers implementing crop rotation, where leguminous plants help to replenish nitrogen content within the soil without the need for fertilizers.

Additional information:
The lifestyle of nitrogen-fixing bacteria includes Azotobacter. Azotobacter improves seed germination and has a beneficiary response on the Crop rate of growth. It helps to extend nutrient availability and to revive soil fertility for better crop response. It’s a crucial component of an integrated nutrient management system thanks to its significant role in soil sustainability.
Clostridium is a genus of rod-shaped, usually, gram-positive bacteria helps denitrification. They convert or reduce the nitrates back to the inert nitrogen gas
Streptomyces are gram-positive, mycelium-forming, soil bacteria that have an important function in mineralization processes in nature and are big producers of the secondary metabolites

So, the correct answer is 'Rhizobium’.

Note: If a plant has been planted newly and is growing slowly, then you'll suspect that there are insufficient organic processes. This is often commonly seen with beans and alfalfa. Poor fixation is attributed to the shortage of native Rhizobium to nodulate the legume, but the cause also can be poor plant nutrition and other plant stresses that inhibit nitrogen fixation. Generally, small nodules are getting to be present after 2-3 weeks after germination.