Title
Enumeration of yeast from a pure culture or diluted solution by methods of direct count, viable count, and turbidity study.
Abstract
The goal for using all three enumeration techniques is to not only understand direct count, viable count, and turbidity study, it is to also understand the advantages and disadvantages of each so that researchers can use them in the most efficient ways when studying microorganisms. The idea was that if the direct count gives a certain number of microorganisms, then the viable count and turbidity study should also give us similar number outcomes of the same organism, taking into account dilutions. The researchers concluded that this did occur better in some methods of enumeration than others.
Introduction
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To make sure that an accurate number of colonies will be produced, several dilutions are necessarily cultured. The procedure in the laboratory involves creating serial dilutions of the sample (1:10, 1:100, 1:1000 etc. ) in a sterile water environment and spread onto nutrient agar dishes that are sealed and incubated. What these nutrient plates consist of, depends on the different types of microorganisms being researched and targeted to grow. In most cases, the bacteria being studied can be easily identified from the nutrient plate. If cells are dispersed on the plate properly, it may be assumed that each cell will grow into a single colony that is seen with the naked eye and is not time strenuous at the moment of counting. In the total amount of time, this could take is a couple of weeks and sometimes does not work as planned, where researchers may get more or fewer colonies than expected. The colonies can be counted and are based on the known volumetric amount of the culture that was transferred to the plate and therefore the cell concentration may be calculated. The grand total of microorganisms found on the plate is called the total viable count (TVC) and is measured in the unit of CFU/mL (colony forming units). To calculate the CFU/mL, the counted number of colonies has to be multiplied by the dilution used. Usually the bacterial colony counts are important …show more content…
From the direct count culture, a serial dilution was completed, and this is where the final dilution had the cell quantity in the countable range of 30-300. For viable count, two Petri dishes were labeled, with “A (1 x 10 ^ -5)” and one “B (2 x 10 ^ -5),” To add, the first 99 mL DI H2O bottle was labeled with “1 to 100” ratio and the other bottle was labeled with a “1 to 10,000” ratio. Lastly, the 9 mL DI water tube was labeled with “1 to 100,000” ratio. Researchers added 1 mL of pure yeast culture into a bottle labeled “1:100” and mixed well. After, they took 1 mL from bottle number 1 and put it into bottle number 2, also mixing well with the 99 mL DI H2O. Taking 1 mL of bottle number 2, researchers added this amount to the 9 mL water tube and mixed well. After the dilutions of the yeast culture, the YED medium was ready to be smeared with yeast dilution. Researchers melted the YED agar bottles and kept it in the water bath with the temperature at 58°C to maintain its liquid form. After that, they poured YPD until the dishes were half full, and in the liquid form, swirled in 1 ml from the 9 mL tube onto plate “A” and 2 mL of the tube onto plate “B”. If the medium was too hot, it would kill the microorganisms off and if too cold, it would cause them to clump. The
2. A test tube was then filled with 35ml of yeast and placed in the
The first day an unknown sample was assigned to each group of students. The first test applied was a gram stain to test for gram positive or gram-negative bacteria. The morphology of the two types of bacteria was viewed under the microscope and recorded. Then the sample was put on agar plates using the quadrant streak method for isolation. There were three agar plates; one was incubated at room temperature, the second at 30 degrees Celsius, and the third at 37 degrees Celsius. By placing each plate at a different temperature optimal growth temperature can be predicted for both species of bacteria.
The first step to the unknown is selecting an actual organism. The best way to select a culture is based on a high-quality distribution. Equally important, shaking up the broth tube facilitates in the distribution. Upon selection, a gram check for purity is performed. Step by step instructions for this procedure can be found in Benson’s, Microbiological Applications p. 99. Furthermore, an aseptic technique must be performed for this test and the entire tests following the unknown. The purpose of this test is to differentiate between gram positive and gram-negative bacteria. The key indicator of gram-positive bacteria is a purple stain and a pink stain for gram-negative bacteria. A slide is viewed with a microscope under oil immersion. Equally
the experimenter added 5 ml of yeast suspension to each one of the ten test
I identified the genus and species of an unknown bacterial culture, #16, and I applied the following knowledge of morphologic, cultural and metabolic characteristics of the unknown microorganism according to the laboratory manual as well as my class notes and power point print outs. I was given an incubated agar slant labeled #16 and a rack of different tests to either examine or perform myself; the tests are as follows: Gram Stain; Nutrient Gelatin Test; Carbohydrate Fermentation; Dextrose, Lactose and Sucrose; IMVIC tests; Citrate, Indole, Mythel-Red and Vogues Proskauer test; as well as a Urease and TSI Test.
The tubes were immediately put in an ice until E. coli was added. Then, we added a single colony of bacteria to both tubes and added the plasmid to the tube labeled +pGLO and returned the tubes to the ice bath for ten minutes. Next, four agar plates were prepared: one that had ampicillin (amp) and arabinose (ara), two with just ampicillin, and one with no alterations. After ten minutes, the bacteria were moved to a hot water bath for 50 seconds and then put immediately back on ice for two minutes. After two minutes, 250 microliters of nutrient broth were added to both tubes and the bacteria incubated at room temperature for ten minutes.
The results shown in table 1 clearly show that when the volume of yeast is increased in the milk solution, so does the rate of oxygen depletion and therefore the rate of eutrophication. It shows that when 2mL of yeast solution was added it took 32.86 minutes on average for the milk to be depleted of oxygen, while it took only 7.46 minutes on average for the 10mL of yeast to use up the oxygen present.
Investigating the Effect of Temperature on the Fermentation of Yeast To fully investigate the effect of temperature on the rate of fermentation of yeast Background Information Yeast is a single-cell fungus, occurring in the soil and on plants, commonly used in the baking and alcohol industries. Every living thing requires energy to survive and through respiration, glucose is converted into energy. There are two types of respiration available to living cells are: 1.
The main characteristics that have made the test standardized are: the incubation temperature at 37ºC, the depth of the agar, a complex media, the concentration of the antimicrobial, and that the organism is equally spread out on the agar (Bauman, R.W.,
The next day, 100 µL of an overnight culture of Salmonella growth will be transfer onto the center of a Petri plate containing tryptic soy agar where taken out from refrigerator. Sprea...
Microbes are everywhere in the biosphere, and their presence invariably affects the environment in which they grow. The effects
Leboffe, M. J., & Pierce, B. E. (2010). Microbiology: Laboratory Theory and Application, Third Edition 3rd Edition (3rd Ed.). Morton Publishing
There were five test solutions used in this experiment, water being the control, which were mixed with a yeast solution to cause fermentation. A 1ml pipetman was used to measure 1 ml of each of the test solutions and placed them in separated test tubes. The 1 ml pipetman was then used to take 1ml of the yeast solution, and placed 1ml of yeast into the five test tubes all containing 1 ml of the test solutions. A 1ml graduated pipette was placed separately in each of the test tubes and extracted 1ml of the solutions into it. Once the mixture was in the pipette, someone from the group placed a piece of parafilm securely on the open end of the pipette and upon completion removed the top part of the graduated pipette.
The abnormal presence of bacterial growth can be inspected under a microscope. If the organism inspected is not the bacteria used in the experiment, it means that the growth of the bacterial culture investigated is absent. By using this method, contamination by foreign substances in the surrounding air can be ruled out and the results would be more accurate.
Culture plates of yeasts strains: S41, a pet 1 and M240, conical flasks containing Yeast Extract Potassium Acetate (YEPA), Yeast Extract Peptone Dextrose (YEPD) and Yeast Extract Palm Olein (YEPPO) media, pH indicator, inoculation loop, microscope, methylene blue, Bunsen burner and incubator.