Unknown bacterial paper
Preformed 09/03/12 read 09/08/12
Streak for Iso- well isolated colonies
Streak plate is an instinctive method used to perform rapid, precise and easy experimentation on a reasonably immense concentration of microorganisms in the dilution process. The method aids in diluting the high concentration of microorganisms by scattering and minimizing the cell concentration. The objective of the experiment is to obtain isolated colonies on the better part of the Agar surface. This allows for the species in focus to resonate into an untainted culture. Well-isolated colonies are a basic entity in the use of streak method. Carrying out streaking without the use of well-isolated colonies renders the plates useless. Well-isolated colonies facilitate in obtaining pure cultures through restreaking the isolated colonies on a fresh agar plate. The identification of bacteria in experiments validity depends entirely on the use of pure cultures without which, the biochemical experiments remain flawed (Lorian 481).
Preformed on 10/17/12 read on 10/22/12
Eosin Methylene Blue (EMB) test- colorless colonies
Eosin Methylene blue used in staining for the purposes of developing viable contrast in microscopic images has significant efficiency in experiments especially in Gram-negative bacteria. Gram-negative bacteria have the incapacity to keep crystal violet dye in Gram staining procedure hence the use of Eosin Methylene. The stain comprises the combination of eosin and methylene blue mixed in a precise ratio of 6:1 used to prepare the EMB agar. The two compounds represent pH indicator dyes that mixed produce a purple precipitate at low pH used also to prevent the growth of a majority of Gram-positive organisms (Lorian 254). Colonies in the experiment appeared colorless from the diamination of proteins from increased levels of pH. Deamination of proteins inhibits the absorption of acid hence rendering the colonies colorless (Lorian 257).
Endo test-dark pink colonies
This is a method implemented in experiments as a tool for secluding and differentiating Enterobacteriaceae and other Gram-negative rods. The method relevance applies to a variety of experiments both in clinical and nonclinical samples (Lorian 250). Endo agar resonates in the sample from the combination of sodium sulfite and basic fuchsin resulting in passive inhabitation of gram-positive bacteria. Dark pink color production in the experiment comes from the fermentation of lactose when reacting to coli forms with the same coloration to the medium.
Preformed on 10/22/12 read on 10/24/12
Motility Test- Negative
The term motility defines the ability of an organism has the capability to move by itself. Motility test helps observe the increase in growth of semi solid agar hence determining the classification of motility in the microorganisms. Motility test is a part of various tests implemented to derive the different Entrerobacteriaceae despite the aspect of the basis of test having a single function medium (Lorian 320). A disinfected needle used in the test pierces the medium and places it at an aggregate of one centimeter from the below the tube. A red growth in the line of axis indicates a negative result of the test. Nonmotile bacteria grow in a soft agar tube and only in the area of inoculation indicated by a negative test from the distinct growth along the line of stab. The picture below indicates the difference in positive and negative motility test (Lorian 342).
Lipase Test
Positive Lipase test consists of a variety of procedures that vary to the medium they apply. In humans, lipase test determines the serum level of a protein in the blood based on its use in digestion. Pancreas produces the enzyme that in the body convert blood lipid into fatty acid. The most common lipase test carried out on microorganisms is the tributyrin test (Lorian 357). Tributyrin main objective is to test an organism’s capacity to produce lipase responsible for breaking down fats. An organism produces lipids to allow it break down lipids into smaller pieces. The presence of tributyrin oil in the agar forms a dark suspension around the medium. If the organism produces lipase, then a transparent halo circumvents the area the organism grows. The difference in the ability of an organism in the test to produce lipase signifies the use of the lipase test. The test is positive from the ability of the bacteria to produce lipase signified by a clearing around the growth.
Preformed on 10/29/12 read on 11/5/12
Methyl Red
Fermentation in organisms in most cases produces numerous stable acids but in other cases produce a reduced number of unstable acids. Methyl-Red test serves the purpose of testing for mixed acid fermentation. Methyl red (MR) and vogues-Proskauer (VP) broth abbreviated as MR-VP broth is a composite of peptone, buffers, and dextrose used to test on organisms mixed acid fermentation capacity. Organisms that have the ability to perform mixed acid fermentation overcome buffering capacity of the broth (Lorian 207). They do this by producing large quantities of acids that result in the decrease of the pH recorded. An organism that does not have the capability to perform mixed acid fermentation lacks the ability of overcoming the barring ability of the broth. Methyl red use in the experiment is to acts as the indicator of pH level in the agar. The methyl red has red coloration if the pH is at an aggregate of 4.4 that essentially renders the result a positive one (Lorian 548).
VogesProskauer
Negative Vosproskauer abbreviated as VP is an experimental test that serves the purpose of detecting acetoin; a colorless liquid that acts as an energy reserve store to a wide number of fermentative bacteria (Lorian 600). VP test identifies the presence of acetoin in a broth of bacterial culture. Alpha-naphthol and potassium hydroxide mix with the bacterial culture broth to produce two distinct colors each indicating a different result. If the color produced from the mixture is cherry red, then the result is positive for acetoin (Lorian 323).
Citrate- Positive
The citrate test performed provides evidence of an organism’s ability to survive on citrate only as the organism’s source of carbon and energy. The test indicates a positive result from the production of alkaline by products of a citrate metabolism (Lorian 432). The indication that the bacteria can survive on citrate is as indicated by the change in color of the pH indicator. The procedure involves picking isolated bacterial colonies in a straight wire and dipping them into a Simmons citrate agar (Lorian 328). If the bacteria can run on citrate as the sole source of carbon and energy, then the medium changes color from green to blue to signify a positive result
Nitrate- Positive
Bacteria have a variety of procedures that applied differentiate their various species. A key method implemented basis on the ability of bacteria to reduce nitrate or nitrogenous gas. Endogenous nitrate conversion to nitrates by bacteria is a key aspect to the viability of the method especially in identifying urinary step strip in humans (Lorian 311). If the test is positive for nitrates, this indicates the presence of gram-negative organisms from their ability to convert endogenous nitrates to nitrites.
Performed on 11/5/12 read on 11/7/12 Antibiotics
Antibiotics
1. Novobiocin- There was no circle
Novobiocin is a unique antibiotic from its ability to buffer the process of DNA replication and bacterial cell cycle. The test determines the resilience of bacteria to novobiocin in distinguishing gram positive cocci since some of them are vulnerable to the drug while others remain resistant to novobiocin (Lorian 402). If there is no circle in the test of susceptibility of bacteria to novobiocin, this shows that the antibiotic does not have the ability to inhibit the bacteria hence leaving cells exposed.
2. Kanamycin- was circle
Kanamycin is an antibiotic used to test the susceptibility or resistance of a bacteria parental culture. The circle formed in the circle represents the zone of inhibition to bacteria as it prevents bacteria from compromising the zone concentrated with antibiotics (Lorian 197).
3. Chloramphenicol- was a circle
This antibiotic is of a broad-spectrum nature and mostly effective in inhibiting gram-positive and gram-negative bacteria. Chloramphenicol acts as the last resort in treatment from its ability to treat serious microorganism infections. This occurs from its high toxicity hence enabling it penetrate infected sites (Lorian 388). The formation of the circle indicates the inhibition zone of bacteria hence resisting their penetration into a secluded area.
4. Tetracycline- was circle
Tetracycline is an antibiotic that works by hindering bacteria from producing protein ergo incapacitating them from growth or multiplying their numbers. The isolation of bacteria from their necessities prevents them from spreading through the infection and those already present annihilated (Lorian 551). The circle represents the spread line of the antibiotic with the circumvented area the infected part. Formation of the circle shows the bacteria vulnerability to the antibiotic.
5. Nalidixic Acid- was circle
Nalidixic acid has proven effectively in both gram positive and gram negative bacteria where it exhibits bacteriostatic behavior in low concentrations. This occurs from its ability to inhibit growth and reproduction. In high concentrations, the antibiotic can kill bacteria without merely suppressing their growth and reproduction process (Lorian 272). It can compromise susceptible bacteria DNA by forcing a relaxation complex aspect to the bacteria DNA gyarse. The circle represents isolation of the bacteria from the infected area and a prevention line from which the bacteria cannot go through (Lorian 285).
Work cited
Lorian, Victor. Antibiotics in Laboratory Medicine. Philadelphia, PA: Lippincott Williams & Wilkins, 2005. Print.
