Question

All are true about bacterial endospores except
A. Sporulation in bacteria is a method of reproduction.
B. The spores of all the medically important bacteria are killed by autoclaving at 121oC for 15 minutes.
C. Spores can be stained by modified Ziehl-Neelsen technique.
D. Bacterial spores help them to survive under unfavourable conditions.

Answer 1

Bacteria is a prokaryotic organism. Bacterial cells are of two types: gram-positive bacteria and gram negative bacteria. Gram positive bacteria have a thick cell wall composed of peptidoglycan and gram negative bacteria has a thin layer of peptidoglycan surrounded by a thick layer of lipopolysaccharide.

Step by step answer: Endospores are heat resistant and dehydrated structures capable of surviving for long periods in an unfavorable environment. These spores are developed within the cell. Endospores are resistant to environmental stresses such as the heat, UV Rays, gamma radiation, chemical disinfectants and desiccation. The structure of an endospore includes exosporium which is a thin delicate protein covering present at the outermost region of the endospore. The spore coat lies beneath the exosporium and is composed of several protein layers. Beneath the spore coat is the cortex which is made up of peptidoglycan. The spore cell wall is present beneath the cortex and it surrounds the protoplast or the spore core. Spore core is metabolically inactive but has ribosomes for protein synthesis and nucleoid that contains the genetic makeup of the cell. Endospores contain large amounts of dipicolinic acid and calcium ions. Endospore morphology and location in a bacteria are detected by Schaffer-Fulton endospore staining. This staining involves heating of the bacteria stained with malachite green. This dye penetrates the endospores and stains them in green colour. After heating the cell is washed with water and its counter stained with safranin. The slide is then observed under the microscope. Portions that are stained with green are the endospores of the bacterium.
Hence option A is correct.

Note: The bacterial endospore is formed in gram positive bacteria. These bacteria are dangerous pathogens and endospores play a vital role in the food industry and medical microbiology. These endospores can be seen in both light and electron microscopes.