Quiz 4 Study Guide Micro Lab

You are doing the presumptive test of a well water sample and you get the following results:

     1 ml single strength phenol red lactose broth tubes

     two tubes yellow with gas in durham tubes

     one tube yellow with no gas in durham tube

   How many of these tubes would be recorded as positive results?

2

Testing water for fecal contamination consists of three parts they are:

presumptive, confirmed, and completed

performed, confirmed, and completed

presumptive, phenol red lactose, and completed

performed, comfortable, and completed

presumptive, confirmed, and completed

Determine the organisms per ml of a food sample given the following information:

102 colonies were counted from the 10-2 dilution tube after 0.1 ml was plated

Give your answer in scientific notation and include the proper units.

1.02 X 10+5 CFU's/ml

102 X 10+3 CFU's/ml

1.02 X 10-5 CFU's/ml

102 X 10-2 CFU's/ml

1.02 X 10+5 CFU's/ml

What color is the agar in a positive citrate utilization test?

blue

What three amino acid substrates can be tested for in the decarboxylation test?

lysine, ornithine, arginine

The black precipitate that may form in a Kligler's Iron agar consists of H2S. True or Fasle?

True

Arrangement of flagella distributed over the entire cell is:

monothrichous

kophotrichous

atrichous

peritrichous

lophotrichous

peritrichous

Most motile bacteria move about with structures called?

flagella

The mere presence of microorganisms in food means that it is unfit for

human consumption.

True

False

False

The formation of fissures or the lifting of the agar off the bottom of the

tube in a Kligler’s Iron agar tube is evidence of the production of

gas

Which of the following statements about coliform testing is true?

all determine the number of E. coli present in a sample

the media employed test for the ability to ferment lactose

a positive test indicates that pathogens are definitely present in the sample

the MPN procedure precisely indicates the concentration of coliforms

the media employed test for the ability to ferment lactose

Each broth for the presumptive part of the water testing lab must

contain an inverted vial called a __________ tube to look for gas

production.

Durham

A  __________ organism migrates away from the stab line in a motility with TTC medium.

motile

In the ____________ arrangement of flagella, there are two or more flagella located at only one end of the cell.

lophotrichous

Citrate agar is the color __________ when alkaline(positive) and __________  when acid(negative).

blue, green

A positive decarboxylase test is considered invalid if the mineral oil overlay was forgotten.

True

False

True

Glucose fermentation in a Kligler's Iron slant is indicated by:

a red butt

a red slant

a yellow slant

a yellow butt

a yellow butt

Name a food that relies on drying for preservation from bacterial contamination.

raisins

What is a positive color for fermentation of the glucose in the decarboxylation test?

Yellow

A Citrate utilization test is positive when the color is:

Blue

All of the following are true of coliforms, except:

gram-negative rod

non-spore-forming

ferments lactose, with the production of acid and gas

ferments sucrose, with the production of acid and gas

ferments sucrose, with the production of acid and gas

Testing water for fecal contamination consists of three parts they are:

presumptive, confirmed, and completed

performed, comfortable, and completed

presumptive, phenol red lactose, and completed

performed, confirmed, and completed

presumptive, confirmed, and completed

A cluster of polar flagella is called:

lophotrichous

monotrichous

amphotrichous

peritrichous

lophotrichous

In the atrichous arrangement of flagella, the filaments are:

located at one end of the cell

located randomly all over the cell

not present

located at both ends of the cell

not present