Nt1310 Unit 9 Lab Report

Negative result is no color change with mineral oil on top of solution. This bacterium has +/- reaction on MAC plate. It could survive in an acidic environment, but it not able to ferment lactose. The bacteria grow on the plate, but did not change the color of the plate to bright pink. This bacterium has a +/- result on Bile Esculin Agar.

8. Discuss a possible mechanism of Gram Staining in terms of differences in structure and chemistry between the walls of gram-positive and gram-negative

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

n.d.). Gram-negative bacteria have a cell wall made up of a thin layer of Peptidoglycan, which is covered with an outer membrane of Lipoprotein and Lipopolysaccharide, and a bipolar-staining coccobacillus is an oval shaped bacterial cell with two poles that is in between coccus and bacillus forms (Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. 2003.). It is also known as an obligate intracellular pathogen, meaning that it is a microorganism causing disease that is only able to survive in a particular environment or by taking on a particular role. This particular pathogen can only survive when concentrated in blood (Sutyak, Katia. n.d.). This fermentative, motile organism produces a thick antiphagocytic, or a cell that prevents the action of phagocytes, slime layer as it moves (Sutyak, Katia. n.d.). Phagocytes are cells that absorb detrimental microorganisms, unwanted material, and other foreign bodies within the bloodstream and tissues (The American Heritage® Dictionary of the English Language, Fourth Edition, Mifflin, Houghton.

The shape of the S. aureus is a Gram-positive spherical bacterium that occurs in grape like clusters, which are golden. The golden color is the result of a carotenoid pigment that protects the bacteria against host-immune system reactive oxygen species, and adds to the bacteria's virulence. Staphylococcus aureus is a gram-positive bacterium, which means that the cell wall of these bacteria consists of a very thick peptidoglycan layer. Whereas NM is a gram-negative, coffee bean shaped aerobe bacterium. The bacterium

There are many similarities and differences between gram positive and gram-negative bacteria. Gram-positive bacteria are weaker than gram-negative bacteria when exposed to

Cell wall of bacteria contains rigid and complex structure which maintains the cytoplasm of cell gives structural integrity and prevents osmotic lysis. Both Garm positive and Gram negative bacteria contain a carbohydrate complex structure called Peptidoglycan also called Muerin. The layer is thicker in Gram positive bacteria whereas in Gram negative bacteria the peptidoglyacan layer is thinner; moreover this is protected by an outer membrane layer called Lipopolysaccharide (LPS). The Peptidoglycan consists of two monomers called N-Acetylglucosamine(NAG) and N-Acetylmuramic acid(NAM). These two carbohydrate containing monomers are linked by glycosidic linkages. A pentapeptide bond attaches to NAM which gives crosslinkage and rigidity to the layer.

Gram positive bacteria have thick peptidoglycan layer, when alcohol (declorizer) is added it dehydrates peptidoglycan thus causes shrinking and tightening of peptidoglycan. The large crystal violet-iodine complex is not able to penetrate this tightened peptidoglycan layer, and is thus trapped in the cell in Gram positive bacteria. Conversely, the the outer membrane of Gram negative bacteria is degraded and the thinner peptidoglycan layer of Gram negative cells is unable to retain the crystal violet-iodine complex and the color is lost.Gram positive bacteria have thick peptidoglycan layer, when alcohol (declorizer) is added it dehydrates peptidoglycan thus causes shrinking and tightening of peptidoglycan. The large crystal violet-iodine complex is not able to penetrate this tightened peptidoglycan layer, and is thus trapped in the cell in Gram positive bacteria.

Gram negative cell walls have a very different and somewhat more complex set up compared to a gram positive wall. For instance, the peptidoglycan is one single layer and is surrounded by an outer membrane that is slightly similar to the cell membrane. One of the unique differences in the outer membrane is that it contains lipopolysaccharides and lipoproteins.

The microbiology of N.meningitis, the gram negative bacteria has two primary layers which it used to protect itself. First is the outer, outside polysaccharide layer which is the outer membrane that plays an important role for the bacteria. The protective membrane acts like an adhesive as well as a barrier between the bacteria and the environment in which it is needed to survive the host. The cell envelope has an outer membrane made up of a peptidoglycan layer and the inside of the cell is made up of cytoplasmic. The outer membrane has an outside layer primarily composed of lipopolysaccharide, and proteins that an inside layer composed of phospholipids that contains proteins primarily responsible for regulating the flow of nutrients and metabolic

It is found that the lipid portion of the lipopolysaccharides that are within the walls of gram-negative bacteria are often toxic which can cause many fever or shock. It is also very resistant toward antibiotics. Whereas the outer membrane of a gram-negative bacterium is the protector from the body’s defenses.

All bacterial cells have a cell wall composed of peptidoglycan, However, they can be differentiated into two broad groups, Gram positive and Gram negative. Gram-positive cells have a thick peptidoglycan layer whereas gram-negative cells have a thin peptidoglycan layer. The cell wall of Gram positive bacterial cells also have large amounts teichoic acids, while Gram negative cells do not have any teichoic acids. Graham negative cells have an outer membrane composed of lipids, lipoproteins, and lipopolysaccharide (LPS). Lipopolysaccharide, Also known as endotoxin, is what makes gram-negative bacterial infections so dangerous because it causes symptoms such as shock and a fever. The outer membrane of gram-negative bacteria is more permeable than

A Gram-negative cell is pink when Gram-stained. Its cell wall is characterized by a relatively thin layer of peptidoglycan. There is no presence of teichoic acids. The layer of peptidoglycan is surrounded by an outer membrane; the outer layer of this membrane is lipopolysaccharide.

Gram-negative bacteria on the other hand secret fewer enzymes into the medium and thus less extracellular drug inactivation is observed with these organisms. Many gram-positive bacteria however do produce the enzyme not retain it in the periplasmic space. This way the drug is inactive after it has diffused across the cell wall but before it binds to its target PBP (Alexey 1999).

Gram positive bacteria is impenetrable to sanitizers because of its thick and well built plasma membrane which is thicker than most viruses and fungus cell’s membranes. This attribute gives great difficulty to alcohol antiseptics and is hard to destroy the proteins inside the cell because of the thick wall.