Disinfectant Lab Report

Even though both sterilization and disinfection are both important there is a big difference between the two. Sterilization is the process of killing all microorganisms. Where disinfection is the process of destroying pathogenic organisms or rendering them inert. The centers for disease control says there is one cardinal rule for infection

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

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

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

Each tests gave us an important characteristics of our bacteria that helped us to identify it. The most imporatant test that we performed was the Gram stain. Gram stain test’s meaning is to differentiate between Gram positive and Gram negative bacteria

A gram stain is performed to identify bacteria as gram positive or negative, and to visualize cell arrangement

Introduction The Gram stain is a technique used to differentiate between two major groups of bacteria based on the composition of their cell wall. It was developed by Hans Gram in 1882. There are three primordia steps. The cells are first stained with crystal violet (followed by a mordant), then they are decolorized with 95% alcohol, and finally counterstained with safranin. Gram positive cells have a thick peptidoglycan layer that entraps the crystal violet and prevents decolorization.

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 Staining             Gram Staining is a procedure used to distinguish between gram-positive and gram-negative bacteria, where one of the main differences is the cell wall. Gram-positive bacteria contain multiple layers of peptidoglycans and gram-negative lacks of peptidoglycans in the cell wall. Overall, is a short procedure that consists of the following steps: first apply the primary stain (crystal violet), second apply the mordant (Gram’s iodine), third apply decolorizing agent (ethanol or ethanol acetone) and finally apply secondary stain (safranin). Another purpose of gram staining is to determine the bacteria’s morphology.

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.

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