Question

An example of symbiotic bacteria is

• A. Erwinia amylovora
• B. Rhizobium leguminosarum
• C. Xanthomonas campestris
• D. Agrobacterium tumefaciens

Answer 1

The correct option is B

Rhizobium leguminosarum

The correct option is B.

Explanation of the correct option:

1. Symbiotic bacteria are bacteria that live in a symbiotic relationship with other organisms.
2. Like rhizobium bacteria associated with root nodules, both the host and the pathogen benefit from the symbiotic interaction.
3. Plants provide a safe haven for rhizobium bacteria, which assists plants in nitrogen fixation.
4. Rhizobium bacteria dwell in nodules or on the roots of legumes in the soil.
5. They create a symbiotic relationship with the legume in the root nodule and benefit from the plant's nutrients.
6. As a result, nitrogen is produced for the process of nitrogen fixation, also known as biological nitrogen-fixing.

Explanation of the incorrect options:

Option A:

1. Erwinia amylovora is a bacteria that was first discovered to be a plant pathogen.
2. It is the cause of fire blight.
3. Fire blight is an apple and pear disease that can be found in various places of the world.

Option C:

1. By darkening the blood vascular tissue of crucifers, Xanthomonas campestris causes black rot.
2. It's a rod-shaped, aerobic, gram-negative bacteria. About 20 different types of plants, including crops and wild plants, have been identified as having unique pathogenicity.

Option D:

1. Crown gall disease is caused by Agrobacterium tumefaciens, which is found in over 140 species of eudicots.
2. It's also a rod-shaped gram-negative soil bacteria.

Final answer: An example of symbiotic bacteria is Rhizobium leguminosarum.