Question

Smallest bacterium among these is
A. Dialister
B. Nitrosomonas
C. Bacillus
D. Spirillum

Answer 1

Hint:- Bacteria are very small, single-celled microscopic organisms found in different environments. They are present in the soil, food, water bodies, even inside other animals including humans.

Complete answer:
Bacteria come under prokaryotes and are single-celled organisms having a primitive body structure without any nucleus. DNA is found floating in either nucleoid or present in plasmids. They usually have two outer layers for protection which are an inner cell membrane, and an outer cell wall. They possess long extensions from their body surfaces such as flagella or pili, which help them in moving from one place to another or in attaching to the host.
Although the bacteria are very small in size with an average size of (0.5 – 1.0) ×( 2.0 – 5.0) micrometers but the smallest bacteria has a size of 0.5 × 0.5 × 1.6 micrometers. The smallest bacterium is Dialister pneumosintes which is a non-fermentative anaerobic bacterium. It was formerly known as Bacteroides pneumosintes. It is a gram-negative bacterium that grows in smooth colonies on the blood agar. It was first isolated from a patient’s nasopharyngeal secretion who was suffering from common influenza.

Thus the correct option is (A) Dialister.

Note:- The relationship of humans with bacteria is very complex. Some bacteria are beneficial for us while others are very harmful to our health. For example, the bacteria Lactobacillus helps in the formation of curd which is very helpful for our digestion, whereas the bacteria Streptococcus pneumoniae causes the deadly disease Pneumonia. The bacteria Dialister has also shown its pathogenic potential and is seen associated with several infections in humans affecting the lungs, teeth, and brain.