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Should The Cuti Plates Be Incubated At And Why?

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2. You have been asked to set up a dilution series, and then use spread plates to determine the viable cell count. Why is it necessary to use a dilution series when isolating bacteria from a biological sample using spread plating? [5 MARKS] It is vital to use a dilution series to reduce the concentration of the original biological sample so it is easier to count the number of isolated colonies which are present on the spread plate. The diluted samples will have a workable number of colonies on the spread plate which can then be used to calculate the number of bacteria which were present in the original undiluted sample. 3. You plate the dilutions onto nutrient agar and chromogenic agar plates. What are the differences between these types …show more content…

4. What temperature should the plates be incubated at and why? [2 MARKS] Both the nutrient and chromogenic plates should be incubated at 37 degrees Celsius because this will mimic the temperature of the birthing pools where the sample is from as well as mimicking the temperature of the human body. 5. You use cUTI plates as the chromogenic media and find that some of the colonies have turned pink in colour. What information does this tell you about the bacteria in the sample, and why did the colony change colour? [2 marks] This tells me that the bacteria in the sample contains coliforms such as Escherichia coli (E.coli). The colonies changed colour as the enzymes produced by the bacterial cells reacted with the red galactosidase in the agar medium, this reaction causes the colonies to turn pink making them easily

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Prelab week 1 Calculations Preparation of 1.5μmol/L mixed low-level standard dilution 150μmol/L × V1=1.5μmol/L × 10ml V1=(1.5μmol/L×10ml)/(150μmol/L)=0.1ml Conversion of milliliters to microliters (0.1ml×1000)μL= 100μL Preparation of 3μmol/L mixed low-level standard dilution 150μmol/L × V1=3μmol/L × 10ml V1=(3μmol/L×10ml)/(150μmol/L)=0.2ml Conversion of milliliters to microliters (0.2ml×1000)μL= 200μL Preparation of 3μmol/L mixed low-level standard dilution 150μmol/L × V1=7.5μmol/L × 10ml V1=(7.5μmol/L×10ml)/(150μmol/L)=0.5ml Conversion of milliliters to microliters (0.5ml×1000)μL= 500μL Preparation of the blank samples The volumetric flask will be filled to the mark with 150μmole/L of stock solution to act as blank (reference). Additional two blanks will

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The colour of each test tube was recorded and if proteins were present that was recorded for each test tube. Finally, the pH was recorded for each sample using pH

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The second ½ of the organism was used for gram staining. The gram stain method was performed on the unknown organism per lab manual page 42 and two gram stain reactions were identified. Organism B was gram positive cocci in grape like clusters. Because organism B was positive I could eliminate Escherichia coli, Enterobacter aerogenes and Proteus vulgaris because these bacteria would be rod shapes. Organism A was gram negative pink rod shaped and because of gram positive morphology I could eliminate Staphylococcus aureus, Streptococcus lactis and Bacillus subtilis.

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The purpose of this lab report is to employ a myriad of skills, tools and, methods learned throughout this semester to perform the appropriate tests for the identification of the assigned unknown bacteria. Add more background information here!!! The most important tools and techniques used during this identification include aseptic technique, microscopic examination and, the use of selective and differential media. Aseptic technique is an important tool for microbiologists. It is imperative that aseptic technique is maintained throughout the length of any test to avoid any cross-contamination that may lead to inaccurate results.

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The unknown bacteria was then tested on multiple selective and differential media. Growth was present on the MacConkey Agar and the colonies were the same color as the plate, which told me my bacteria was gram negative and did not ferment lactose. There was no growth on the Mannitol Salt Agar, and this told me the unknown was not salt tolerant and did not

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Hypothesis If E coli bacteria is added to all four agar plates, then both of the agar plates labeled +pGLO and the -pGLO plate without ampicillin would grow. Variables The independent variables in this experiment is the addition of pGLO, ampicillin, and arabinose. The dependent variables in the experiment are whether or not bacterial growth occurs, or if the bacteria grow. The constants in the experiment are the size of the agar plate, the temperature in which the agar plates incubate, and the length of time the

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This particular titration requires complexometric indicators which form weak complexes with the analyte. A common use of this titration is with calcium and magnesium ions. During assay titrations serial dilutions are completed on a fixed ratio of a sample repeatedly until the final dilution proves no positive result for the existence of a virus, the infected cells are then inspected under a microscope to determine the overall value whether that be positive or negative. How are preparations of standard solutions and titration carried out in modern industrial laboratories?

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The concentration of the stock solution 2.0x 10-4M as per label information in the lab. However, the calculated volume using the experimental data is 1.5 x 10-4M.There is 25% difference between these concentration caluclated from zero time intercept. The significant difference in the concentration drop happened by many factors. First,the rate ionization is depend the pH because pKa determines the equlibrium between p-nitrophenol and its depronated form p-nitrophenolate. Although,the pH is maintained by buffer at 7,not all of the p-nitrophenol produced by the chymotrpsin catalysis is not its depronated form.

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My unknown mixture of bacteria was red in color. It was Coccus bacteria, which is round in shape. Its dimensions were 2.5 micrometers on 40x small division lens. Heterocysts are thick walled specialized cells. They are responsible for nitrogen fixation.

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From the Unknown tube professor Cooper gave me, I scratched a little on the slant surface with the sterilized inoculating loop. Then I place it on a clean prepared slide which already had a slight drop of water. The two substances are mixed together in the middle of the slide and let dry completely. One extra step of “heat fix” is necessary to adhere everything to the surface of the slide. To start gram staining, I slightly pour crystal-violet all over the slide and let it sit for 30 seconds before wash it off with water.

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Counting the bacteria means determining the number of bacteria in a specific sample. There are many ways that we can use to count the microorganisms, one of which is the plate count. The plate count technique is used to count only the living bacteria by counting the number of colonies. Due to the large number of bacteria, and to be able to count it, the bacteria should be diluted several times and spread on an agar plate. In this way, colonies can be counted.

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The Another medium used was MAC, it is used to isolate and differentiate gram-negative organisms and it is a pink, dusty rose color. Lastly, the Citrate Slant is a green color and it was used as a differential test to examine enzymes. The media were inoculated at 37°C for 48 hours, then it was observed to determine the

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This technique is used to isolate prooteins, enzymes as well as antibodies from m mixtures. Partition Chromatography: Here the stationary phase is a thin liquid film either adsorbed or

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