Top 30 Difference between Gram Positive and Gram Negative Bacteria

Bacteria are the Prokaryotic, single-celled organisms. The structure of bacteria is quite simpler than almost all the other organisms as it lacks a nucleus and membrane-bound cell organelles.

The control center of the prokaryotic cell or bacteria hangs freely inside the cell as a single loop of DNA in which the genetic information of the bacteria is stored.

Some of the bacteria contain special genes which give them some extra features or advantage over other bacterial cells. This storage of genetic material is called Plasmids.

For example, the bacterial cell may contain a plasmid or gene that makes the bacterium resistant to some of the Antibiotics.

Broadly, Bacteria are classified into 5 groups according to their basic shapes as follows:

  • Spherical (cocci)
  • Rod (bacilli)
  • Spiral (spirilla)
  • Comma (vibrios)
  • Corkscrew (spirochaetes)

Bacterial arrangement varies as single cells (Monococcus), in pairs (Diplococci), chains (Streptococcus) or in clusters (Staphylococcus).

Bacteria are Ubiquitous, can be found in almost every habitat on the Earth: Soil, Rock, Oceans and even Arctic Snow.

Some bacteria live inside or on the surface of other organisms including plants and animals including humans (e.g. Normal Flora of Human and Gut Bacteria).

Inside the human body, in the Lining of the Digestive system, approximately 10 times more bacterial cells are present as compared to human cells in the human body.

Some bacteria live in the soil or on the dead plant matter (Saprophytes) where they play an important role in the nutrient cycles (e.g. Nitrogen Fixation).

Some of the bacteria spoil food and damage various plants and crops and others help in the production of various food items like yogurt, Soy sauce, fermentation reactions etc.

There are certain bacteria which are parasites or pathogens and cause various deadly diseases in humans, animals, and plants.

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One of the most popular staining method used to distinguish the bacteria on the basis of their cell wall composition and some other properties is the Gram Staining Technique.

Gram staining classifies the bacteria into two groups as Gram-positive and Gram-Negative Bacteria.

This staining technique was formulated by Danish bacteriologist Hans Christian Gram in the year 1884.

Gram staining is always used as the first step in the preliminary identification of the bacteria from the specimen.

Gram staining is an important diagnostic tool in both clinical and research laboratory but there is some limitation that all the bacteria cannot be classified by this technique.

Thus, a few other groups were identified as classified as the Gram-variable and Gram indeterminate.

Below is the list of Top 30 Difference between Gram positive and Gram negative bacteria:

S. No.CharacteristicsGram Positive BacteriaGram Negative Bacteria
1.)Gram Reaction ResultsRetains Primary stain (Crystal Violet) and appears Blue/Purple colored cells.Retains Counter stain (Safranine) and appears Red/Pink colored cells.
2.)Cell wall thicknessThick (20-80 nm)Thin (8-10 nm)
3.)Peptidoglycan LayerThick (multilayered)Thin (single-layered)
4.)Rigidity and ElasticityRigid and less elasticLess rigid and more elastic
5.)Outer MembraneAbsentPresent
6.)Variety of amino acid in cell wallFewSeveral
7.)Aromatic and Sulfur-containing amino acid in cell wallAbsentPresent
8.)Periplasmic SpaceAbsentPresent
9.)Teichoic AcidsMostly presentAbsent

S. No.CharacteristicsGram Positive BacteriaGram Negative Bacteria
11.)MorphologyUsually cocci or spore forming rods.Usually non-spore forming rods.
12.)Lipid and Lipoprotein ContentLowHigh
13.)Ratio of RNA:DNA8:1Almost 1:1
14.)Structure of Flagella2 rings in basal body4 rings in basal body
15.)MagnetosomesUsually Absent.Sometimes Present
16.)Lipopolysaccharide (LPS) NegligibleHigh
17.)Endospore formationSome produce endospores during unfavorable conditions.Usually not produce endospores.
18.)Toxin ProducedExotoxinsEndotoxins or Exotoxins
19.)PathogensFew pathogenic bacteria belong to Gram positive group.Most pathogens are Gram negative.
20.)Nutritional RequirementsRelatively ComplexRelatively Simple

S. No.CharacteristicsGram Positive BacteriaGram Negative Bacteria
21.)Resistance HighLow
22.)Susceptibility to Penicillin and SulfonamidesHighLow
23.)Cell Wall Disruption by LysozymeHighLow
24.)Susceptibility to Streptomycin, Chloramphenicol and TetracyclineLowHigh
25.)Inhibition by Basic DyesHighLow
26.)Susceptibility to Anionic DetergentsHighLow
27.)Resistance to DryingHighLow
28.)RenderingThey can rendered Gram -ve by increasing acidityThey can rendered Gram +ve by increasing alkalinity
29.)Resistance to Sodium AzideHighLow
Clostridium etc.
Pseudomonas etc.

That’s all about 30 Difference between Gram Positive and Gram Negative bacteria

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