Section II (15 points) (a) i. Which of the cultural methods of microbial analysi

Question

Section II (15 points) (a) i. Which of the cultural methods of microbial analysis would you use to determine the numbers of yeast in 3.78 liters of pasteurized grape juice which has a very low microbial count (less than 1.0 CFU of yeast per 100 ml). ii. Provide a step by step explanation of how the method can be used in analyzing the juice. iii. What are the advantages of your method of choice over other cultural methods? (b) Are there currently used methods of microbial analysis that could give the precise number of live bacteria in food? (Write YES or NO). If your answer is YES, state the name of one such method, briefly describe the method and explain why the method is accurate. If your answer is NO, give reasons for your answer.

Explanation / Answer

a)1. Fluoroscence microscopy procedure-used for beverages and liquid samples

2.procedure- filter aliquot with milipore filter and then use milipore disc filter holder which attaches to standard syringe.Press all sample through filter paper.Keep the filter holder vertical for even distribution of sample over filter and then remove filter from the holder and place on microcope.the grids must be parallel to edge of slide for counting.

3.advantages-viable and non viable cells can be counted and used for filtered beverages specifically.

b) yes

plate counting method for identifying viable bacteria cells.

method- sample is diluted by factor of 10 and placEd on nutrient agar and then incubated.after this plate with30-300 colonies is determined.and then calculate cfu.at the end of incubation colonies counted by eye.

it is accurate- agar used has reagents that resist growth of non target organisms.and make target easily identifiable.

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