1. A water sample was collected from Monona Bay to enumerate total and fecal col

Question

1. A water sample was collected from Monona Bay to enumerate total and fecal coliforms using the MPN method. From this water sample a 10-1 to 10-6 dilution series was prepared. this series was used to inoculate a full set of LLTB with Durham tubes. Below is a table of the results for the LLTB.

Each tube that was positive for the presumptive test was inoculated into BGLB and EC. Below is a table of the results. The numbers indicate those tubes that were positive for growth and gas.

a. What is the bacteria/mL of presumed coliforms in the initial water sample? Show your calculations.

b. what is the bacteria/mL of total coliforms in the initial water sample? Show your calculations.

initial dilution 10-1 10-2 10-3 10-4 10-5 10-6 turbidity +/+/+ +/+/+ +/+/+ +/+/+ +/+/- -/-/- gas +/+/+ +/+/+ +/+/- +/+/- -/-/- -/-/-

Explanation / Answer

There are a number of variants to the multiple fermentation tube technique. The most

common procedure is to process five aliquots of water from each of three consecutive 10-fold

dilutions; for example, five aliquots of the sample itself, five of a 1/10 dilution of the sample

and five of a 1/100 dilution. Aliquots may be 1-ml volumes, each added to 10 ml of single-

strength culture medium, or 10-ml volumes, each added to 10 ml of double-strength medium.

Results are compared with values such as those

3 of 10 ml each

3 of 10 ml each

3 of 1 ml each 3 of 0.1 ml each MPN 0 0 0 <3 0 0 1 3 0 0 3 1 0 0 4 1 0 1 7 1 1 0 7 1 2 1 11 1 0 0 11 2 0 0 9

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.