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Difference between Gram positive and Gram negative bacteria

THE Gram-positive bacteria keep the crystalline violet and yes they color purple, while I Gram-negative bacteria they lose the crystal violet and turn red from contrast of safranin . So with the Gram staining technique and the color that keep crystal purple or does not describe the characteristics of the bacteria, as they are characterized as positive or negative.

The technical word " Gram coloring "born from the Danish bacteriologist Christian Gram in 1884 . This stains a weak alkaline solution of a crystalline violet. Although it is an old technique, it still considers the cornerstone in the field of microbiology for bacterial identification.

Bacteria are the oldest form of cell life. They are also the most dispersed, occupying every possible microclimate on the planet. The composition of the prokaryotic cell wall is used to classify bacteria into four main classes: gram-positive bacteria, gram-negative bacteria, bacteria without cell walls and bacteria with chemically different cell walls.

In the article provided we will interpret the difference between gram positive and gram negative bacteria and also some similarities.

Comparison table

Basis for comparisonGram positive bacteriaGram negative bacteria
SenseThose bacteria that give a positive gram stain test result and absorb the purple crystal spot are called positive gram bacteria.Bacteria that are unable to maintain the crystal purple color and show negative results on the gram stain test are called gram-negative bacteria.
ExamplesStreptococcus, Clostridium, Lactobacillus, Bacillus subtilis, Leuconostoc.Vibrio, Rhizobium, Escherichia coli, Acetobacter.
Color obtained after coloring in gramsIt appears dark purple or purple when viewed under a microscope after gram staining and maintains crystal violet color after washing with alcohol.It appears as in red or pink when viewed under a microscope after gram coloring and safranin counter-color.
Cell wallSingle layer.Double layer.
Straight and uniform.Wavy and irregular.
Less elastic and more rigid.More elastic and less rigid.
The stiffness of the cell wall due to the high amount of peptidoglycan, which is about 80%.The elasticity of the cell wall due to the lower amount of peptidoglycan, which is around 2-12%.
The cell wall has muramic acid, which represents about 16-20% of the total dry weight of the cell.The muramic acid content is only 2-5% of the total dry weight.
The cell wall shows alkali resistance.The cell wall sensitive to alkalis.
The cell wall contains theic acidTheic acid absent in the cell wall.
The cell wall susceptible to degradation by the action of the enzyme called lysozyme.The cell wall less sensitive to degradation by the action of lysozyme.
The thickness of the cell wall can be up to 15-30 nm or sometimes it can be 80 nm.The thickness can be between 8 and 12 nm in the cell wall range.
Other characteristicsThe periplasmic space absent or if present, therefore very narrow.Periplasmic space present.
The low lipid content, which is around 1-4%.The high lipid content around 11-22%.
The outer membrane is absent.The external membrane present.
The proteinaceous membrane channel called as porins are absent.Porins are present.
Lipopolysaccharides absent.Lipopolysaccharides present.
The flagellar structure has two rings in the basal body.The flagellar structure contains four rings in the basal body.
Produce endospores, at the time of unfavorable conditions.Do not produce endospores.
Making exotoxins.Produce endotoxins.
Suffering from antibioticsThe vancomycin antibiotic used to kill them.No effect of the antibiotic vancomycin.
The cell shows less susceptibility to chloramphenicol, tetracyclines, streptomycin and high susceptibility to sulfonamide and penicillin antibiotics.The cell exhibits a high susceptibility to sulfonamide, penicillins and low susceptibility to chloramphenicol, streptomycin and tetracyclines.

Definition of Gram positive

Being prokaryotic organisms, the cell of Gram-positive bacteria has many distinct characteristics, but mainly Gram-positive bacteria differ from Gram-negative bacteria in the content present in their cell wall . As we know that gram-positive bacteria maintain the purple, due to the presence of the thick peptidoglycan layer in the cell wall.

The cell has the cytoplasmic membrane lipids; form the lipoteicoic acid (the combination of lipids and theic acids) which acts as a type of adhesion. The smallest periplasmic space compared to gram negative bacteria. The flagellates present in some species have solo support two rings of the basal body .

Some species may also contain the capsule containing polysaccharides. They have a surface layer known as a layer S, which attached to the peptidoglycan layer.

The three basic forms they are bacillus (rod-shaped), coccus (spherical), spiral (twisted). Gram-positive bacteria include streptococci, staphylococci, pneumococci, bacillus anthracis (which causes anthrax), Corynebacterium diphtheria which causes diphtheria.

They are also known to cause diseases such as skin infections, septic arthritis, osteomyelitis, endocarditis, tuberculosis, etc. Therefore, antibiotic treatment is administered to the patient suffering from this disease, which is easy to cure but can also be life-threatening.

They are also known to cause diseases such as skin infections, septic arthritis, osteomyelitis, endocarditis, tuberculosis, etc. Therefore, antibiotic treatment is administered to the patient suffering from this disease, which is easy to cure but can also be life-threatening.

Definition of negative Gram

In addition to certain similarities, there are also some distinct characteristics, such as the cell wall of these organisms that of peptidoglycan very thin and located between the internal and external bacterial membrane of the cell, due to which it is unable to retain the crystal violet color and counterstains safranin and appears to be red or pink. These three components (internal and external membrane together with the peptidoglycan layer) make up the cellular casing .

Gram-negative bacteria have one cytoplasmic cell membrane ; the outer membrane consisting of lipopolysaccharide . They have pores in the outer membrane, which functions like the pores of the molecules.

The S-layer attached directly to the outer membrane and the flagellum has four rings of support . Periplasma is a gelatinous substance present between the outer and cytoplasmic membranes. Theic acid absent in them.

Escherichia coli the model of organisms in this category, while others are Neisseria gonorrhoeae, Pseudomonas aeruginosin, Chlamydia trachomatis, Yersinia pestis. Antibiotics include aminoglycosides and carbapenems.

The unique character of Gram-negative bacteria is the presence of outer membrane, which protects bacteria from many antibiotics, chemicals, detergents and dyes. Therefore other substitutes such as lysozyme, EDTA, ampicillin and streptomycin have been developed to meet them and therefore protect against pathogenicity.

The outer layer consisting of lipopolysaccharide, in which the lipid portion behaves like an endotoxin. If these bacteria enter the circulatory system, the lipopolysaccharide will show toxicity and therefore cause respiratory problems, blood pressure.

Key differences between Gram positive and Gram negative bacteria

The following are the substantial differences between the two types:

  1. Gram-positive bacteria are those bacteria that give the positive result of the Gram stain test and absorb the crystalline violet stain, while those bacteria that are unable to maintain the violet-crystal color and show the negative result of the Gram stain test are called Gram-negative bacteria .
  2. The color obtained after coloration grams of gram-positive bacteria purple crystal is red or pink in gram-negative, contrasting safranin.
  3. Examples Gram-positive bacteria are Streptococcus, Clostridium, Lactobacillus, Bacillus subtilis, Leuconostoc, while Vibrio, Rhizobium, Escherichia coli, Acetobacter are the example of gram negative bacteria.
  4. The cell wall single layer, straight, uniform, less elastic and more rigid and the stiffness of the cell wall due to the high amount of peptidoglycan, which about 80% in gram-positive bacteria while in gram-negative bacteria the double-layer cell wall , wavy, irregular and more elastic and less rigid where the elasticity of the cell wall due to the lower amount of peptidoglycan, which is around 2-12%.
  5. The cell wall of gram-positive bacteria has muramic acid, which about 16-20% of the total dry weight of the cells and even the cell wall shows alkali resistance, also contains theic acid, while the cell wall of alkali-sensitive gram-negative bacteria, muramic acid only 2-5% of the total dry weight and theic acid is absent in the cell wall.
  6. The thickness of the cell wall varies from 15-30 nm and susceptible to degradation by the action of the enzyme called lysozyme, although in gram-positive bacteria the cell wall is less susceptible to degradation by action of the lysozyme and the thickness varies from 8-12 nm.
  7. Gram-positive bacteria they produce exotoxins, while the periplasmic space is absent and, if present, very narrow and the gram-negative bacteria produce endotoxins, lo periplasmic space present in them.
  8. The outer membrane absent in gram-positive bacteria. In addition, the lipid content only 1-4%, while in external gram-negative bacteria the membrane present in gram-negative bacteria. In addition, the lipid content of 11-22%, which is very high.
  9. The other features like the channel of the protein membrane called porins, lipopolysaccharides are absent and produce endospores in unfavorable conditions, but are present in gram-negative bacteria, although they do not produce endosporzioni .
  10. There flagellar structure it has two rings in the basal body of gram-positive bacteria, while the gram-negative flagellar structure contains four rings in the basal body.
  11. The cell of gram-positive bacteria shows less susceptibility against chloramphenicol, tetracyclines, streptomycin and high susceptibility to sulfonamide antibiotics and penicillins, while the cell of gram-negative bacteria shows a high susceptibility towards sulfonamide, penicillins and low susceptibility to chloramphenicol, streptomycin and t,.

Similarities

  • Both are prokaryotic organisms.
  • The nucleus, the nuclear membrane and other organelles linked to the membrane fail to develop well.
  • They closed circular DNA as genetic material and also contain plasmid (extra-chromosomal genetic materials).
  • Their cell wall consists of peptidoglycan and the cytoplasm surrounded by the lipid bilayer.
  • Both have a surface layer called the S-layer.
  • Both undergo the type of sexual reproduction as well as asexual, in which conjugation, transformation and transduction are the sexual methods while binary fission is the asexual process.
  • Both categories contain many flagellated and non-flagellated species.

Conclusion

Bacteria are single-celled, prokaryotic and microscopic organisms, which are found everywhere acquiring almost all types of habitats. These are the dominant living creatures on earth. They can be useful or harmful to us. Since they are responsible for causing many diseases in plants, animals and humans, but sometimes they play the role of ecological benefit for the environment in fixing nitrogen, degrading cellulose, etc.

Bacteria are mainly classified as gram positive or gram negative; this differentiation due to the staining technique known as the Gram staining method. We also discussed their characteristics and how they are distinct from each other.