Question

Which bacteria cannot grow on synthetic media?
A) E. coli
B) Lactobacillus
C) Rhizobium
D) Mycobacterium leprae

Answer 1

Bacteria are the microorganisms that can be found everywhere in the favourable as well as in extreme conditions. They constitute a large domain of prokaryotic microorganisms. Bacteria have a number of shapes and sizes.

Complete answer :

A growth medium or culture medium is a solid, liquid or semi-solid which is designed to support the growth of a population of microorganisms.
Synthetic medium is chemically made medium and entirely free of the animal derived components.
Synthetic culture mediums represent the purest and most consistent cell culture environment.
Synthetic medium culture is composed of solely biochemicals of low molecular weight.
E.coli – E. coli is a rod shaped gram negative bacterium which is the resident of human intestine. They can rapidly grow on mediums that contain a carbon compound such as glucose and salts that provide nitrogen, phosphorus to the bacterium.
Lactobacillus – Lactobacillus is a gram positive rod shaped bacterium. They are anaerobic bacteria which means they perform their metabolic reactions in the absence of Oxygen. These bacterium convert the sugars to the lactic acid. These bacteria grow on Agar medium best.
Rhizobium – Rhizobium is a bacteria that can be extracted from the root nodules of the leguminous plants. It is symbiotically associated with the roots of leguminous plants and fix the atmospheric nitrogen in the form of nitrogen that plants can uptake like nitrates, nitrites, etc. For the culturing of this bacteria, broth medium is used.
Mycobacterium leprae – It is a bacterium which causes leprosy. Leprosy is a chronic infectious disease that damages the peripheral nerves and targets the organs like skin, nose, eyes and muscles. They can be cultured on an artificial medium not on a synthetic medium.
Therefore, it has been clear from the above discussion that Mycobacterium leprae is a bacterium that cannot be grown on synthetic media.

Hence, option D is the correct answer.

Note: Bacteria are classified into four groups on the basis of their shapes-

Cocci – spherical shaped
Bacilli – rod shaped
Spirilla – spiral shaped
Vibrio – comma shaped