Introduction:
Bacteria create an enormous domain of prokaryote microorganisms that are diverse and abundant in most habitats on Earth. In fact, bacterial cells drastically outnumber somatic cells just on the external part of the human body compared to somatic cells within the whole body of a single individual. Bacteria are found just about anywhere on earth and are usually alongside other microorganisms including: mold spores or yeast cells, creating some difficulty when trying to distinguish between the two. It is extremely important to be able to differentiate the bacteria from the other microorganisms. In this lab the goal is to identify an unknown bacterial species located in the biology building, so being able to differentiate the microorganisms that we find will lead to success. Bacterial cells are unicellular and extremely small in size, about 1 μm. Bacterial cells are found in colonies that rapidly spread and grow. These colonies can range in color, size, surface area and structure. There are numerous edges, surface forms, elevation types, and shapes of the whole bacterial colonies. All of these physiognomies are used to differentiate between the different colonies. Bacterial Colonies come in many different colors varying from white and yellow, to red, pink, or even green. When trying to distinguish bacteria from other nearby microorganisms, it may be extremely difficult to tell the difference between bacteria and yeast. Yeast colonies have a very similar morphology to bacterial colonies. However, mold colonies are drastically different and easy to differentiate between them and bacteria colonies. Mold spores are large, contain a fuzzy area which is brightly colored. The purpose of the Bacterial Diversity project is to collect, growth, and identify an unknown species of bacteria. …show more content…
The most important step in analyzing an unknown species of bacteria is to categorize it as Gram-positive or Gram-negative. Bacteria is made up of different chemical composition of cell walls, this allows for the gram test to classify between the two major types. Gram-positive bacteria has a thick layer of peptidoglycan located in the cell wall, while Gram-negative bacteria have a thin layer of peptidoglycan layer in the cell wall. The Gram test is a staining technique that can detect the peptidoglycan in the cell walls of bacteria. The Gram-positive bacteria cells retain a colored dye in it’s thick peptidoglycan wall and appear purple to blue in color. Gram-negative bacteria cells do not have a thick peptidoglycan layer and are not able to retain the violet dye. However, Gram-negative cells can pick up the safranin counterstain and appear red to pink in color. The Gram test must be done with great precision and skill which can make it difficult to carry out positive results. Thus, simpler tests have been designed to carry out this experiment and differentiate between Gram-positive and Gram-negative bacteria Another test designed is the KOH string test. This test is one way to distinguish between the two types of bacteria cells, Gram-positive and Gram-negative. This test is performed by using 3% KOH on a glass slide and mixing it with cells from a concentrated bacterial culture that was collected. If the KOH string test shows the formation of string like substance from the mixture, the test will be considered KOH “positive” and will represent Gram-negative bacteria. Gram-negative bacteria cells that are mixed with the KOH allows for a string like substance to appear because the KOH destroys the think peptidoglycan cell wall which causes the DNA to adhere to each other and form a chain that looks like a string. On the other hand, Gram-positive bacteria cells would test negative to the KOH string test due to its thick peptidoglycan cell wall. The thick layer would not permit the KOH to destroy its strong cell wall. This test is not always accurate and can allow false negative to occur. This can happen if there was extra KOH added to the mixture, too much or not enough of the culture added to the mixture (Holbrook, Leicht 24). Along with the KOH test, other tests that can be carried out to distinguish the type of bacteria we are identifying includes growing the bacteria cells on plates of different kinds of media. The different types of media commonly include antibiotics or some type of inhibitor to inhibit the growth of one specific
Bacteria create an enormous domain of prokaryote microorganisms that are diverse and abundant in most habitats on Earth. In fact, bacterial cells drastically outnumber somatic cells just on the external part of the human body compared to somatic cells within the whole body of a single individual. Bacteria are found just about anywhere on earth and are usually alongside other microorganisms including: mold spores or yeast cells, creating some difficulty when trying to distinguish between the two. It is extremely important to be able to differentiate the bacteria from the other microorganisms. In this lab the goal is to identify an unknown bacterial species located in the biology building, so being able to differentiate the microorganisms that we find will lead to success. Bacterial cells are unicellular and extremely small in size, about 1 μm. Bacterial cells are found in colonies that rapidly spread and grow. These colonies can range in color, size, surface area and structure. There are numerous edges, surface forms, elevation types, and shapes of the whole bacterial colonies. All of these physiognomies are used to differentiate between the different colonies. Bacterial Colonies come in many different colors varying from white and yellow, to red, pink, or even green. When trying to distinguish bacteria from other nearby microorganisms, it may be extremely difficult to tell the difference between bacteria and yeast. Yeast colonies have a very similar morphology to bacterial colonies. However, mold colonies are drastically different and easy to differentiate between them and bacteria colonies. Mold spores are large, contain a fuzzy area which is brightly colored. The purpose of the Bacterial Diversity project is to collect, growth, and identify an unknown species of bacteria. …show more content…
The most important step in analyzing an unknown species of bacteria is to categorize it as Gram-positive or Gram-negative. Bacteria is made up of different chemical composition of cell walls, this allows for the gram test to classify between the two major types. Gram-positive bacteria has a thick layer of peptidoglycan located in the cell wall, while Gram-negative bacteria have a thin layer of peptidoglycan layer in the cell wall. The Gram test is a staining technique that can detect the peptidoglycan in the cell walls of bacteria. The Gram-positive bacteria cells retain a colored dye in it’s thick peptidoglycan wall and appear purple to blue in color. Gram-negative bacteria cells do not have a thick peptidoglycan layer and are not able to retain the violet dye. However, Gram-negative cells can pick up the safranin counterstain and appear red to pink in color. The Gram test must be done with great precision and skill which can make it difficult to carry out positive results. Thus, simpler tests have been designed to carry out this experiment and differentiate between Gram-positive and Gram-negative bacteria Another test designed is the KOH string test. This test is one way to distinguish between the two types of bacteria cells, Gram-positive and Gram-negative. This test is performed by using 3% KOH on a glass slide and mixing it with cells from a concentrated bacterial culture that was collected. If the KOH string test shows the formation of string like substance from the mixture, the test will be considered KOH “positive” and will represent Gram-negative bacteria. Gram-negative bacteria cells that are mixed with the KOH allows for a string like substance to appear because the KOH destroys the think peptidoglycan cell wall which causes the DNA to adhere to each other and form a chain that looks like a string. On the other hand, Gram-positive bacteria cells would test negative to the KOH string test due to its thick peptidoglycan cell wall. The thick layer would not permit the KOH to destroy its strong cell wall. This test is not always accurate and can allow false negative to occur. This can happen if there was extra KOH added to the mixture, too much or not enough of the culture added to the mixture (Holbrook, Leicht 24). Along with the KOH test, other tests that can be carried out to distinguish the type of bacteria we are identifying includes growing the bacteria cells on plates of different kinds of media. The different types of media commonly include antibiotics or some type of inhibitor to inhibit the growth of one specific