Experiment 6 - 10 and quizzes

Flagella are used by many microorganisms for _________ .

locomotion

Structure of flagella differs among the ________ .

three domains of life

Eukaryotic flagellum

• made of microbtubules

• driven by dynein motor proteins

Prokaryotic Flagellum

made up of a filament, hook, and basal body/motor and has a rotating motor

The curved hook in prokaryotic flagellum

connects basal body to the extracellular component of the flagellum, the filament

Bacteria are anchored by a complex of proteins in the cell enveloped called the ________ .

basal body or motor

The filament of prokaryotes is made of _______ .

flagellin proteins

The current model for the movement of bacterial flagella is by a ____________ .

rotary motor (proton gradient provides energy to rotate it

• force to spin motor proteins happens when protons flow back into the cell through mot proteins (near motor)

Polar

one or more flagella attached to the ends of cells

• has many forms

Amphitrichous

has flagella on each end

Monotrichous

singe flagellum attached on one end

peritrichous

flagella found at multiple locations

lophotrichous

a tuft of flagella are attached to one of both ends

Motility Test medium

• Helps determine if bacteria have flagellum and are motile

• Low agar concentration (0.4%)

• Contains tetrazolium salt (TTC)

• should be kept refrigerated till inoculation

Tetrazolium salt (TTC)

• makes interpretation of results easier

• Colorless and soluble in oxidized form

• When reduced: red and insoluble

  • Non-motile bacteria: red only along stab line

  • Motile bacteria: red radiating out from stab line

streak plate

determines what in culture

Serial dilution and plating

• Determines “how much” is in a culture

• Serial dilution is used in conjunction with spread plating

• Expressed in terms of cfu/ml

  • Colony forming units per milliliter of culture

Dilutions

• With each consecutive transfer you are decreasing the number of bacteria present in each dilution tube

• sometimes referred to as 10-fold serial dilutions

Bacterial counts can be used to determine _______.

the growth rate of a lab culture or the level of contamination in a food, urine, or water sample

spread plating

• Uses the entire plate

• Pipette a known amount into the center of the plate and spread the inoculum over the entire surface of the plate using a spread rod

• more expensive and sensitive

TNTC for spread plates

more than 300 colonies

TFTC for spread plates

less than 30 colonies

Spot plating

• four separate dilutions on a single plate

• Spot” 25 µl aliquots of each dilution tube onto an appropriately labeled quadrant

• Count the number of colonies within each spot

• Adjust the numbers to a per ml basis

  
  

TNTC for spot plates

more than 25 colonies per spot

TFTC for spot plates

less than 5 colonies per spot

formula for cfu/mI

#colonies x reciprocal of dilution x (1000/amt plated in ul)

cfu/ml numbers can be used in the following

• UTI’s (Urinary tract Infections) – Only considered an active infection if plated cfu/ml exceeds 10⁵

• Used in food and water safety

• Estimate the amount of protein and or DNA based upon viable counts in a population for research purposes

To prepare a "spot" plate; how many spots should you have in each quadrant?

3 spots

How much should you be aliquoting onto spot plates?

25 uL

How much should you be aliquoting onto your spread plate?

100 uL

What tool will you use to spread around the sample for your spread plate?

spread rod

How much are your transferring for each dilution?

500 uL

Which two dilutions will you use for your spread plate?

10-6 and 10-7

You inoculate a Motility Test Deep with an unknown bacterium. After 24 hours of incubation, you see that there is red only by the initial stab life. What does this mean?

bacterium does not have flagellum, non-motile

fomites

contaminated inanimate objects

reservoir

continual source of infection

An infectious virus consists of _________. 

nucleic acid and capsid

PEA is partially inhibitory to _________. 

gram-negative organisms

Which of the following media is not differential?

• PEA

• MSA

• MAC

• PSP

PEA

If a bacterium is capable of growing on MSA, what two characteristics do you know about it?

it is halophilic and mostly likely a Staphylococcal species

Which of the following is not a result for TSI?

• motility

• acid production

• gas production

• H2S production

motility

After inoculation and incubation, you notice a simmons-citrate tube is blue. Is this a positive or negative result?

positive

Reagents are added __________ .

after incubation

You inoculate a set of OF glucose tubes with an unknown bacterium. The following are the results:

+ tube: yellow

- tube: green

What type of ability does the organism have to catabolize glucose?

fermentative

The carbohydrate fermentation tube appears orange after inoculation and incubation with a bubble in the durham tube. What is this bacterium positive for?

weak acid producer and gas production

Starch agar plates test for the presence of ___________; whereas, spirit blue test for the presence of ___________. 

amylase; lipase

You observe the following results:

No reagents have been added

MR: visible growth; cloudy broth - no color change

VP: minimal growth on the bottom of the tube - no color change

What is the next step?

add Methyl Red to MR tube and VP1 and VP2 to VP tube