Here is an image of a UV-irradiation (wavelength 254nm) experiment performed on a plate of E. coli after incubation. Which side of the plate do you think has a 'zero-minute' negative control? A or B or neither? Explain with proper reasoning.
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- Here is an image of a UV-irradiation (wavelength 254nm) experiment performed on a plate of E. coli after incubation. Which side of the plate do you think has a 'zero-minute' negative control? A or B or neither? Explain with proper reasoning. ICA Exoli Eoli kyEscherichia coli Mycobacterium phlei Bacillus Micrococcus subtilis luteus A B Figure 1: Agar Slant Cultures of Bacteria (Gary E. Kaiser, Ph.D.- Professor of Microbiology) . Observe and describe the colour of the slant cultures (A-D) in fig 1. ( . Define the following terms: pure culture, sterile medium, inoculum, aseptic technique, and colony. What is the name of the cultures that you used . Where they gram negative or positive Define the following terms: psychrophile, mesophile, thermophile, and hyperthermophile.In an experiment to calculate the decimal reduction time for an Escherichia coli culture, viable cells were exposed to a constant temperature of 80°C for a set amount of time. After exposure, the remaining number of surviving cells were counted. Based on Table 1, what is the decimal reduction time?Table 1. Decimal Reduction Time for E. coli Heated to 80°C Total time of exposure (minutes): Number of Microbial Cells Present: 0 100 1 80 3 50 4 42 6.5 26 13 10 21 0
- A serial dilution of overnight E.coli culture was performed by pipetting 1ml of a bacterial culture into a 9 ml LB medium. After this, from 10-4 and 10-5 dilution tubes 100µl were plated onto LB agar plates. Upon overnight incubation at 37°C, 200 colonies were counted in 10-4 and 22 colonies were present on 10-5 plates. How many colony-forming units were present per ml of the original culture? If the formula for CFU/ml =no. Of colonies/dilution factor*volume of culture plateHow would you produce a 10^-1 dilution if a 3 mL bacterial sample using the entire 3 mL volume? suppose your professor handed you a test tube with 2.0 mL of an E. coli broth culture in it and told you to make a 10^-1 dilution of the entire culture. Explain how you would do this. Show your calculations.Below is a diagram of four different antibiotics (numbered 1-4) that are being tested in a petri dish inoculated with bacteria. After a sufficient incubation period, bacterial growth occurred except in the zones of inhibition (shown with dotted lines in the diagram) around the antibiotics. Based on the results shown here, would it be reasonable to conclude that the most effective antibiotic in this example would be an effective antibiotic against any bacterium? Why or why not?
- You have several different media onto which you inoculated eight strains of yeast (A-H). The media include a rich medium, an unsupplemented minimal medium, and minimal media each supplemented with one vitamin. Of the yeast strains, one is a prototroph and seven are auxotrophs for a vitamin. After overnight incubation, the following results were observed (tan patches represent growth): D plate 1 (A) B DE F GH plate 5 plate 4 plate 6 Which plate contains an unsupplemented minimal medium? [Select] Which plate contains a rich medium? [Select] plate 2 Which strain is a prototroph? [Select] Strain E is an auxotroph for niacin. Which plate reveals this specific auxotrophy? [ Select] plate 3 plate 7 One strain is an auxotroph for both choline and pantothenic acid. Which one is this most likely to be? [Select]A culture of S. cerevisea has an overnight OD of 4.5 (1.0 OD is approx 1.0x107 cells/ml) You will be plating 100µl onto agar and want the final count of colonies on the plate to be around 300 colonies. How much of the 4.5 OD culture must you use to get a 500µl subdilution (with sterile water), so that you have diluted enough to get approx 300 colonies per 100ulTRUE OF FALSE: Is E coli colonies would be pink mucoid in Eosin Methylene BlueAgar (EMBA)? Is Coliform colonies would be pink mucoid in Eosin Methylene BlueAgar (EMBA)?
- A pure bacterial culture of unknown concentration was diluted to determine the concentration of viable bacteria in the original culture. Serial dilutions were performed as 2. diagrammed below. A volume of 500 µl was transferred into each tube. TSA plates were inoculated with 100 µl from the last three dilution tubes. a. If the dilution between each tube is 102, what is the volume of diluent in each of the 5 dilution tubes? Provide the volume using ml as the units. b. What is the total dilution of tube number 4? Express the total dilution using scientific notation. c. What is the concentration of viable bacteria in the original culture? Express the concentration using scientific notation and CFU/ml as the units. d. If you inoculated a TSA plate with 1.0 ml from dilution tube 4, how many colonies would you expect to form on the plate after incubation? e. If the original culture had a volume of 50ml, what was the total number of viable bacteria in the 50 ml of the original culture? 1 2 3…Two flasks of E. coli are grown in batch culture in the same medium (2% glucose and amino acids; no nitrate) and at the same temperature (378C). Culture #1 is well aerated. Culture #2 is anoxic. After 16 hours the following observations are made: ■ Culture #1 has a high cell density; the cells appear to be in stationary phase, and the glucose level in the medium is reduced to 1.2%. ■ Culture #2 has a low cell density; the cells appear to be in logarithmic phase, although their doubling time is prolonged (over 1 hour). The glucose level is reduced to 0.2%. Why does culture #2 have so little glucose remaining relative to culture #1, even though culture #2 displayed slower growth and has less biomass?A pure bacterial culture of unknown concentration was diluted to determine the concentration of viable bacteria in the original culture. Serial dilutions were performed as 1. diagrammed below. Each dilution tube contained 400 ul of diluent and 100 ul was transferred into each tube. TSA plates were inoculated with 100 µul from the last three dilution tubes. a. What is the dilution between each tube shown in the diagram below? Express your answer as a ratio. b. What is the total dilution of tube number 5? Express your answer as a ratio. c. What is the concentration of viable bacteria in the original culture? Express your answer using scientific notation and the units CFU/ml. d. What is the concentration of viable bacteria in tube number 2? Express your answer using the units CFU/ml. e. If you inoculated a TSA plate with 250 µl from tube number 5, how many colonies would you expect to see after the plate was incubated? 1 2 3 5 423 80 13 Number of colonies