If all, great, if preference just #3 most importantly Uu arl& microbiologist for
ID: 189475 • Letter: I
Question
If all, great, if preference just #3 most importantly Uu arl& microbiologist for Quik Analysis Laboratories, Inc., a company that provides microbiological services for various industries. A new company, Wag and Shake, has developed a new line of protein milk shakes specially formulated for dogs with no teeth. Unfortunately, there have been some possible illnesses linked to its consumption. Before the shakes are shipped to the worldwide market, you have been asked to analyze the shakes for possible bacterial contamination. Turn in your answers to Dr. Rudolph by Friday Feb. 2, 2018. A late penalty of 1 point per day will be applied. Don't make any mistakes or Fido may suffer intestinal distress! 1. Suppose you have a sample of the possibly contaminated dog shake. You serially dilute it using a 1:10 dilution scheme and liquid nutrient agar as the diluent. You then aseptically mix and pour the diluted samples into sterile Petri plates (of course you remember to do everything in duplicate). After incubation, you observe the following colony counts: Plated Dilution Average CFUs/ml dilution -1 TNTC (too numerous to count) TNTC 10 TNTC 1390003 10 10 10 10 6 139 What is the concentration of bacteria in the original sample? Dog food specifieatnsetht ogod can hate n more than 10x 10 bacteria/ml. Therefore, is it a good time to buy stock in Wag and Shake? 2. Suppose you know the concentration of bacteria in a sample of the dog shake is 2.3 x 10 bacteria/ml. Which 1:10 dilution will give you countable plates? You are asked by your supervisor to dilute the dog shake by 1:4 instead of 1:10. You want to make 16 ml of the diluted sample. How much of the dog shake would you use? How much sterile distilled water would you use? 3.Explanation / Answer
1. no. of colonies in the original in the original sample, i.e,
the concentration of the bacteria = (no.of colonies*dilution factor) / volume of culture
for calculations, the dilution having 20 to 200 colonies is chosen
Therefore, based on the formula and the data, the 10^-4 is chosen with 139 colonies.
(139*10^4)/1 (assuming 1ml of dog shake was used for the dilution) = 1.39*10^6 bacteria/ml.
As the number of colonies in the sample is higher than the allowed value, it is not a good time to buy stock in Wag and Shake.
2. 2.3*10^8 bacteria/ml is the original concentration
10^-1 dilution will have 2.3*10^7 bacteria/ml
10^-2 dilution will have 2.3*10^6 bacteria/ml
10^-3 dilution will have 2.3*10^5 bacteria/ml
10^-4 dilution will have 2.3*10^4 bacteria/ml
10^-5 dilution will have 2.3*10^3 bacteria/ml
10^-6 dilution will have 2.3*10^2 bacteria/ml i.e, 230 bacteria
therefore, 10^-6 dilution will give countable plates
3. For 1:10 dilution, 1ml of dog shake is diluted with 9ml of sterile distilled water.
In the same way, for 1:4 dilution, 1ml of dog shake will be diluted with 3ml of sterile distilled water for 4ml of sample.
for 16ml of sample, multiply by 4. Therefore, 4 ml of dog shake will be used and 12 ml of sterile distilled water will be used.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.