LAB 8 Flashcards
Zone of inhibition
the area around the disk in which no bacteria grows and determines the susceptibility rating of bacterium to a specific antibiotic
Sensitive
if a bacterium is susceptible to the effect if an antibiotic (kills or inhibits growth)
Resistant
not susceptible to an antibiotic
Intermediate
Some bacteria may be gaining resistance to the antibiotic
*Another concentrations or multiple antibiotics are needed
Another form of horizontal gene transfer, Cells pick up free DNA from the environment
Transformation
Cells will secrete exoenzymes into the environment and digest large molecules, like DNA, into its base components and then bring it into the cell
Endocytosis
Cells that expressed a protein system on their surface which allows them to move intact ssDNA into the cells
Competent
What is the process of transformation
- Competent cells express DNA binding protein
- Once bound, a nuclease domain on the complex will digest one of the strands of DNA bound to the complex
- The undigested ssDNA will then be transported into the cell intact
- Once in the cell, it undergoes homologous recombination, delivering novel traits into the host cell
- If its a plasmid, DNA can circularize and synthesize its complementary strand and exist extra chromosomally
The family are gram-negative rods that ferment glucose
Can be normal gastrointestinal microbiota, opportunists, and pathogens
Salmonella, E coli
Enterobacteriaceae
Allows us to determine their presence of enzymatic activity because some enzymes cause changes in the pH of the media
Differential media
Combined media that tests for motility, sulfur reduction to hydrogen sulfide, indole production from amino acid tryptophan
SIM MEDIA
the enzyme that hydrolyzes the amino acid tryptophan to produce indole and pyruvate
trytophanase
Glucose, sucrose, lactose
Triple sugars
tests for the ability to use citric acid utilization
Media contains sodium citrate as the sole carbon source
Simmons citrate agar
Differentiates bacteria based on sugar fermentation and sulfur reduction
Differentiates bacteria on fermentation of glucose, sucrose, and lactose or not
How to tell is positive?
Triple sugar iron (TSI) agar
Positive - yellow
If the entire tube is yellow - bacteria fermented the glucose and at least 1 other
GAS - observed by breaks in the agar
Differentiates bacteria based on the presence of the enzyme urease
Urea Agar
Helps differentitate many members of the Enterobacteriaceae based on color
Chromagar
Tests that help differentiate many members of the Enterobacteriaceae family based on color
Often used for UTI
Chromagar orientation
How can we induce transformation in the lab
SIM MEDIA
How to tell if there was a sulfur reduction?
How to tell if its motile?
How to tell if indole production?
Sulfur reduction -
Positive - black
Negative - no black
Motility-
Positive - grows away from stab line
Negative - grows on stab line
Indole production
Positive - Cherry red on top
Negative - light yellow on top
Simmons Citrate test
How to tell if positive or negative
*used citrate as their carbon source must have enzyme - Citrase
Positive if - blue
negative - green
How to know if Urea agar is positive?
Positive = pink
Chromagar helps differentitate many members of the —– family, rapidly based on color
Enterobacteriacea
What media is used for rapid differentiation of gram-negative bacteria in UTI
chromagar
We can induce transformation in the lab by using
heat shock and CaCl2
What is the chemical reaction for indole?
Tryptophanase hydrolyzes the amino acid tryptophan into indole and pyruvate
Explain the types of metabolic processes that can be observed from TSI
Fermentation - of glucose, sucrose, lactose or not
H2S production - to detect sulfur reduction
Gas - produced during fermentation
Peptonization - when bacteria use amino acids for food
conversion - use sugars then amino acids
Name a pathogen that produces H2S but does not ferment lactose or sucrose
salmonella
name a pathogen that may inhibit the stomach and produces urease enzyme?
helicobacter pylori
Name a pathogen that is motile and produces indole
Proteus vulgaris
Name a pathogen that is non-motile but ferments glucose
Providencia stuartii
3 properties of Enterobacteriaceae
Gram-negative
live in the GI tract
either flora, opportunists, or pathogens
