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- Given a log phase bacterial culture with 1 x 10^6 cells per ml and a generation time of 30 minutes how long does it take the culture to reach a density of 6.4 x 10^7 cells per ml?arrow_forwardA 0.00001 dilution is performed on a culture of bacteria in order to perform viable plate counts. From the dilution, *0.1 mL* of solution is plated on solid media, and 223 colonies of bacteria grow on the petri dish. Assuming each colony came from a single bacterium, how many bacteria are in a single mL of the original culture? Express your answer to two decimal places using exponential notation. Since only 0.1 mL is put on the plate, this counts as an extra dilution!!! Any time less than 1 mL is transfered, a dilution is being performed. Any time more than 1 mL is transfered, a concentration is being performed.arrow_forwardThe students of a Microbiology class were tasked to transfer or subculture a pure culture of Escherichia coli bacterium in five 7 mL nutrient broth and five petri dishes of nutrient agar with 20 mL capacity each. Based on the instruction bottles for nutrient broth and nutrient agar, preparation of the culture media is as follows. Nutrient broth: 8 g/liter Nutrient agar: 28 g/liter Answer the following: a. What is the weight in grams of nutrient broth? b. What is the weight in grams of nutrient agar? c. What is the distilled water in mL for nutrient broth? d. What is the distilled water in mL for nutrient agar?arrow_forward
- A microbiology student was given a mixed culture of two different gram positive bacteria species to grow into a culture medium using correct aseptic techniques. After two days,one gram positive bacterial species grew on the media and the growth appeared red on the surface of the medium. Tthe second gram positive bacterial species grew and the growth appeared yellow on the surface of the medium. What is the possible explanation for the differences in the color of the bacterial growth? A. the culture was contaminated B. the microbiologist put too much inoculum on the culture medium C. the medium was a selective medium D. the medium was differentialarrow_forwardHow 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.arrow_forwardPer the USDA, whole, unpasteurized fresh eggs can contain no more than 50,000 CFU/mL bacteria in a standard plate count. You are curious if the fresh eggs that you buy from your neighbor are considered safe to consume so you use your eScience Microbiology kit to test these eggs using direct plate count after serial dilution. After you complete the experiment, you obtain 74 countable colonies from the 10-2 dilution plate. The inoculum volume you plated was 0.1 mL. How many bacteria are present in 1 mL of the egg you sampled? Are these eggs considered safe to consume per USDA standards?arrow_forward
- If you were using the quadrant streak plate method to plate a very dilute broth culture ( with many fewer bacteria the broth used for the plate picture here), would you expect to see single, isolated colored in quadrant 4 or quadrant3? Explain your answer.arrow_forwardA culture of E. coli is diluted as follows:(1) 65mL are added to 435mL of water.(2) 10uL from (1) are then added to 9.99mL of water.(3) A 10-3 dilution is made from tube # (2).(4) 100uL from (3) are plated for a pour plate and incubated. There were 34 colonies counted on one quarter of the plate following incubation. a) What was the overall dilution?b) How many cfu/mL were present in the original culture?c) How many milliliters of water is needed to make a 10-3 dilution using 1000 uL from the original culture?arrow_forwardIn 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 0arrow_forward
- There are so many microbes in a single mL of culture, it is very difficult to perform one dilution to produce countable cells. Microbiologists need to perform a dilution series, where multiple dilutions are performed in sequence to arrive at the correct dilution. Dilutions are cumulative. Multiple the series of dilutions together to find the final dilution value. If 3 serial dilutions are performed, each with a value of 0.01, what is the cumulative dilution? Express your answer as an exponent, e.g. 0.1 would be 1e-1 and 0.01 would be 1e-2arrow_forwardAfter inoculating and incubating an agar slant from a pure broth culture of a bacterial species such as E. coli, which of the following would indicate an unsuccessful aseptic transfer? (Choose ALL that apply) a - There is fungal growth in the original broth culture tube. b- There is too much growth on the agar slant. c- There are colonies of similar morphology on the slant. d - There are red, yellow, and white colonies on the slant. e - There is no growth on the slant.arrow_forwardA 10-5 dilution is performed on a culture of bacteria in order to perform viable plate counts. From the dilution, *0.1 mL* of solution is plated on solid media, and 278 colony forming units grow on the plate. How many bacteria are in a single mL of the original culture? Express your answer to two decimal places using scientific notation. In scientific notation 540 would be written as 5.40*10^2. Since only 0.1 mL is put on the plate, this counts as an extra dilution!!! Any time less than 1 mL is transferred, a dilution is being performed. Any time more than 1 mL is transferred, a concentration is being performed. Include the trailing zero so there are two decimal places Canvas expects a single digit before the decimal point. 5.40*10^2 is how Canvas expects 540 to be formatted in scientific notation 54.00*10^1 would be marked wrong. 0.54*10^3 would be marked wrong. A 10-5 dilution is performed on a culture of bacteria in order to perform viable plate counts. From the…arrow_forward