Tag: botany

Streptomycin is an antibiotic which is used in the treatment of bacterial infections. It belongs to the Aminoglycoside antibacterial class. It is a broad-spectrum antibiotic. It is effective against both Gram-positive and Gram-negative bacteria. It is used in the treatment of tuberculosis, endocarditis, plague, rat bite fever. 

Both Gram negative and Gram positive bacteria have a peptidoglycan layer in the cell wall. The peptidoglycan in Gram negative bacteria is present in the periplasmic space. Apart from this, Gram negative bacteria have an outer wall made up of lipopolysaccharide. Peptidoglycan is also called as mucopeptide. It is a polymer that is made up of sugars and amino acids. 

Gram staining procedure is based on the principle of the ability of microorganisms to retain color of the stains used during the gram staining process. Gram-positive bacteria retain purple color after staining with crystal violet stain. They are not decolorized by treatment with alcohol. Gram-negative bacteria also get stained with crystal violet stain. However, they are decolorized by the alcohol and lose purple color. When again stained with the second stain safranin, they retain pink color. This major difference is due to the difference in the cell wall component of both the bacteria. 

Both Gram negative and Gram positive bacteria have a peptidoglycan layer in the cell wall. It is also called as mucopeptide or murein. However, Gram positive bacteria have thick layer of peptidoglycan. Hence, mucopeptide is abundant in the cell wall of gram positive bacteria. Gram negative bacteria have thin layer of mucopeptide. Apart from this, Gram negative bacteria have outer wall made up of lipopolysaccharide. 

The mucopeptide is a peptidoglycan that is insoluble in nature. It is also called as murein. It is present in almost all bacterial cell walls. However, its percentage is higher in cell wall of gram positive bacteria than in cell wall of gram negative bacteria. 

It holds receptor molecules that help bacteria detect and respond to chemicals in their surroundings

Gram positive bacteria differs from Gram negative bacteria in having multiple layers of peptidoglycan. They have 20–30 nm thick and smooth cell wall. They contain 70-80% murein or peptidoglycan in cell wall. They do not have outer membrane like Gram negative bacteria, which have an outer LPS layer. Due to absence of outer LPS layer, Gram positive bacteria has two rings in basal body of flagellum, one attached to the plasma membrane and one attached to the peptidoglycan wall. They have prominent mesosomes. Mesosomes are folded invaginations of the plasma membrane.

Teichoic acids are found within the cell wall of most Gram-positive bacteria such as species in the genera Staphylococcus, Streptococcus, Bacillus, Clostridium, Corynebacterium, and Listeria, and appear to extend to the surface of the peptidoglycan layer.