What Makes Gram-Negative Bacterial Cells

The Gram stain was used to determine if the bacteria was gram positive or negative. A negative test shows a pink color and a positive test is a purple color. When a bacterium is negative it is because it has an outer membrane and a thin layer of peptidoglycan that is much harder to stain. A positive bacterium has a thick layer of peptidoglycan and no outer membrane that can be penetrated by crystal violet.

This means that the bacteria for this lawn have cells that are surrounded by a cell wall which includes a thin layer of peptidoglycan and surrounding that is an outer lipid membrane that does not contain the Gram strain. Yet at the same time while Kanamycin was the most effective the Ampicillin and Penicillin had reactions as well. The Ampicillin would kill both Gram-positive and Gram-negative so this could indicate that there are Gram-negative bacteria in the lawn, but the fact that the Penicillin worked as well was what was interesting. This means that this bacterial lawn contains both gram-positive and gram-negative bacteria. Gram-positive are bacteria with cell walls that contain a thick layer of peptiodoglycan that retains the Gram strain. For plate 2, trashcan lid, only the Kanamcyin worked which indicates that the only bacteria in this lawn are Gram-negative, but if that is true why didn't the Ampicillin work at all? Ampicillin works to kill both positive and negative grams, but there was no reaction this time. Could it be that it needs more

The peptidoglycan layer differs between a gram negative and gram positive cell. A gram negative cell has a thinner peptidoglycan layer, while a gram positive cell has a thicker peptidoglycan layer that results in a more complex NAM and NAG cross-linking.

This experiment was given to us to utilized previous knowledge learned throughout the semester to identify a gram negative unknown bacterium. We had to first learn the difference between a gram negative and a gram positive organism. We started off with doing gram stains to determine whether it was positive or negative. Based on the gram stains, a gram positive stains purple and a gram negative stains pink. A gram positive stains purple because the cell walls is made of a thick peptidoglycan layer and doesn’t

The Gram-positive cell wall is composed of peptidoglycans, a thick layer of protein-sugar complexes taking up 60-90% of their cell wall. Peptidoglycan is composed of two glucose derivatives, N-acetylmuramic acid and N-acetylglucosamine alternated and cross-linked by tetrapeptides that is composed of L-alanine, D-glutamine, L-lysine

Gram negative and gram positive bacteria differ from each other in many ways especially in the composition and size of their cell walls. Unlike Gram-positive bacteria, Gram-negative bacteria have a thin peptidoglycan layer surround by an outer membrane. This outer membrane contains many proteins one of them being lipopolysaccharides (LPS), which contributes to the bacteria’s negative charge. One part of this protein is a lipid, called Lipid A, which is considered an endotoxin because this lipid triggers an immune response stimulating fever

Escherichia is a genus of aerobic gram-negative rod-shaped bacteria of the family Enterobacteriaceae that form acid and gas on many carbohydrates, such as dextrose and lactose, but not acetone, which include occasional pathogenic forms, including some strains of E. coli which are normally present in the human intestine as well as other forms which typically occur in soil and water (Webster). Escherichia coli is a gram-negative bacilli that rarely varies in shape and size and when stained often resemble safety pins because the ends of some bacilli stain more densely than does the middle; which is a characteristic called bipolar staining which is common in enteric gram-negative bacilli (ASM). Gram negative cells have a thin cell wall layer and will stain red to pink. The staining process is the same as Gram positive, requiring four steps: applying a primary stain, adding a mordant, then rapid decolorization and completing with a counter stain. Applying the alcohol for decolorization dissolves the outer membrane and leaves small holes in the thin peptidoglycan layer through which the crystal violet-iodine diffuse. The gram-negative bacteria is colorless after the decolorization; therefore adding safranin

Bad bacteria are also known as gram negative gut bacteria. These bad bacteria play an active role in the production of inflammatory metabolites such as lipopolysaccharides or LPS. LPS is made of fats and sugar. Normally, LPS provides structural protection to benign bacteria. However, once leaked from the gut

In addition, gramnegative bacteria are resistant to macrolide and Blactam antibiotics due to outer membrane adaption. The antibiotics

The cell structure of salmonella gastroenteritis consists of: gram-negative bacilli, the cell envelope of salmonellae contains a complex lipopolysaccharide structure. The lipopolysaccharide can work as an endotoxin, and may be important in determining virulence of the organisms. The endotoxin complex consists of several components, an outer O-polysaccharide coat, a middle portion, and an inner lipid A coat. This structure is important for various reasons. Firstly, the environment of the sugar units in the outer O-polysaccharide chains is in charge of O antigen specificity; this may also help determine the virulence factor. Salmonellae missing the complete sequence of O-sugar repeat units are called rough because of the bumpy appearance of the colonies; they tend to be less virulent than the smooth strains which contain a complete complement of O-sugar units. Secondly, antibodies that are against the middle portion will protect against infection by a wide range of Gram-negative bacteria; this may moderate their lethal effects. Lastly, the endotoxin factor of the cell wall has an important role in the pathogenesis of several clinical phenomena’s of Gram-negative

Endotoxin are bacterial lipopolysaccharides (LPS), and is formed especially by lipids and sugars. It is present in the outer cell envelope of gram-negative bacterias and its purpose are to maintain the cell membrane intact. The endotoxin is the principal component of the bacterial membrane. (Raetz, 2002)

As learned in class, Coliforms are a group of bacteria’s’ mostly found in the large intestines of humans and animals. Coliform bacteria can also be found in water and in soul. They are gram-negative bacteria’s, meaning that they have a peptidoglycan layer and another layer of the cell wall. These bacteria are also a rode shape now as bacilli. As we all know or should know by now, gram negative cells have a equine structure to their cell wall other cells like acid fast and gram positive do not have. They have a hairy looking type of structure projecting from the outer layer of the cell wall and they are called endotoxin. As the name suggests, Endotoxin is toxin made within the body,

In the natural environment, organisms form a complexity of relationships, these interactions aid the composition and maintenance of genetic variation within ecosystems. The interaction of a predator with its prey offers one such example. To become a successful predator an organism is likely to be subject to trade-offs. This project aimed to begin identification of phenotypic trade-offs, and the genes that control them, during the predation of multiple bacterial species by the social amoeba Dictyostelium discoideum. The study looked to increase tractability of previously used bacterial virulence assays by completing multiple experiments on a single 24-well plate. The assay displayed the Gram-negative bacterium, Klebsiella aerogenes to be

M. tuberculosis cell wall is made of many lipids including peptidoglycan and mycolic acids. Hydrophobic molecules making up Mycolic acids form a lipid layer surrounding the organism affecting permeability of the cell surface. This layer is responsible for many pathogenic inducing traits of M. tuberculosis by inhibiting attack from lysosomes, reactive oxygen species (ROS) and cationic proteins in phagocytes. Further pathogenesis of the bacterium is achieved by the presence of other lipids which include cord factor, sulfolipids and phosphatidylinositol

In all areas of biology, it is easy to see that structure is related to function. This statement holds true in microbiology as well, the study of microorganisms, including bacteria. One characterizing feature of bacteria is the cell wall, which can generally (although not in all situations) be categorized into one of two categories: either Gram positive or Gram negative. Gram positive bacteria’s cell walls are composed of a large peptidoglycan layer (up to 90% of their cell wall). Within this large peptidoglycan layer, one can find techoic acids, which contribute to the maintenance of cell wall structure, and lipotechoic acids, which attach to membrane lipids. Gram positive bacteria that act as pathogens can also potentially release exotoxins, which can have very dangerous effects on humans. Gram negative bacteria, on the other hand, have a very small layer of peptidoglycan in their cell wall, which is surrounded by an outer membrane. Within the outer membrane, one can find the lipopolysaccharide layer, which is one of the most distinguishing factors of Gram-negative bacteria. It is important to note that Gram negative bacteria fail to possess techoic