Bacteria are a large group of microscopic, unicellular organisms and have been grouped into prokaryotic, which means the absence of the nucleus and they have a simple internal structure, including capsule, cell wall, DNA, Flagellum, Pilli, Cytoplasm, and Ribosomes. They exist in every place around us and are present in communities of millions. In length, the complete bacteria measure only a few micrometers.
A bacterium is a singular word for bacteria. The study of bacteria is known as bacteriology and it’s a branch of microbiology.
Types of Bacteria
There are several different types of bacteria and are mainly classified by their:
- Shapes: coccus, Bacillus, Vibrio, spirillum or spirochete.
- Cell wall composition: Gram-positive and Gram-negative.
- Nutritional Patterns: Autotrophic or heterotrophic.
- Mode of Respiration: Aerobic or Anaerobic.
Here, let us explore more information about the difference between Gram-positive and Gram-negative bacteria.
Difference between Gram-positive and Gram-negative Bacteria
|Gram-positive bacteria||Gram-negative bacteria|
|Cell Wall||Smooth and single layered||Wavy and double layered|
|Cell Wall thickness||20 to 80 nanometres||8 to 10 nanometres|
|Porins||Absent||Occurs in Outer Membrane|
|Mesosome||It is more prominent.||It is less prominent.|
|Morphology||Cocci or spore-forming rods||Non-spore forming rods.|
|Flagella Structure||2 rings in basal body||4 rings in basal body|
|Lipid content||Very low||20 to 30%|
|Toxin Produced||Exotoxins||Endotoxins or Exotoxins|
|Resistance to Antibiotic||More susceptible||More resistant|
|Examples-||Staphylococcus, Streptococcus, etc.||Escherichia, Salmonella, etc.|
|Gram staining characteristics||
These bacteria retain the crystal violet color even after they are washed with acetone or alcohol and appear as purple colored when examined under the microscope after gram staining.
These bacteria do not retain the stain color even after they are washed with acetone or alcohol and appear as pink colored when examined under the microscope after gram staining.
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