lab final practical final

what does TDT stand for?

thermal death time

how do you determine TDT?

testing to see at what time a bacteria stops showing growth at a certain temperature

what is pasteruization? what temperature corresponds to this process

pasteruizstion is killing most of the vegetative cells in 30 minutes

how is boiling different than pasteruization

boiling kills most vegetative cells in 10 minutes

Do gram positive and gram negative bacteria respond differently to heat treatment? If so, why or why not?

They respond the same

Does B sub (old) respond differently to heat treatment than B. sub (young)?

Yes because B sub old makes endospores and endospores are more heat resistant

Describe the growth of bacteria that were kept at 4 celsius and 60 celsius

There was no growth at either temperatures

How did these samples compare after incubating them at 37 degrees celsius?

• The 4 degrees celsius showed growth and the 60 did not. This is because at 4 degrees the bacteria was static and at 60 it was cidal

How does distance from UV source affect growth of bacteria?

Increase distance of UV source increases how much bacteria grows

Why did we have to remove the lids from our petri  dishes when exposing them to UV radiation?

Because lids would block the UV

What two types of UV damage repair mechanisms are found in bacteria?

DNA photolyase (faster and more efficient) and endonuclease (only one that works in the dark)

Which ones work when visible light is present?

Both work when light is present

What are some examples of halogens?

bleach and idoine; they are broad spectrum

What type of disinfectant works well against gram negative bacteria, specifically?

Alcohols and phenoyls because they can dissolve the outer membrane

what does MIC stand for?

Minimum inhibitory concentration, which is the least amount of chemical needed to kill a microbe

How does the MIC relate to the size of the zone of inhibition?

Small MIC - large zone of inhibition inverse relationship

What types of antibiotics were NARROW spectrum in lab?

Narrow were penicillin(G+) and polymyxin B(G-)

What types of bacteria were “troublesome” bacteria?

Troublesome bacteria were B sub old (endospores), mycobacterium (mycolic acid in cell wall makes it difficult for chemicals to enter the cell) and pseudonomas because they have small or narrow porins on outer membrane

Would penicillin be more effective against E.coli or staph aureus? Why?

It would be more effective against staph aureus because it is gram positive

What types of bacteria is Rifampin (a nucleic acid synthesis inhibitor) effective against?

Rifampin in broad so it would effect both gram negative and gram positive

Would polymyxin B produce a large or a small zone of inhibition against S. aureus?

Polymyxin B would produce a small zone of inhibition against S aureus because S aureus is gram positive

would polymyxin B produce a large or small zone of inhibition against P. aeruginosa?

Pseudomonas aeruginosa would have a large zone of inhibition

To make DNA samples move faster in gel electrophoresis, how could we manipulate:

• Agarose concentration:

  • Decrease the concentration

• Voltage: 

  • Increase the voltage

Are the charges set up correctly on the following DNA gel electrophoresis?

No, because DNA is negatively charged, so the positive needs to be at the bottom to pull the DNA towards it

Where would we find larger fragments of DNA? At position A or B?

• Larger fragments of DNA would be at A because it didn’t move too far

What do we use to digest (cut) DNA?

Restriction enzymes

What does RFLP stand for?

Restriction fragment length polymorphism

What structure can R+ bacteria make?

R+: plasmid (donor cell), antibiotic resistance (Rfactor) and sxx pilus

What is the purpose of that structure that R+ makes?

Purpose of sex pilus moves plasmid from one bacteria to another

If a bacteria is R+ and is antibiotic resistant, where can the gene for antibiotic resistance be located?

On the plasmid

If a bacteria is R- and antibiotic resistant, where can the gene for resistance be located?

on the chromosome

halogens examples

chlorine, iodine (broad)

heavy metals examples

gold, silver, mercury (broad)

oxidizing agents examples

H2O2 (broad)

Phenols/alcohols examples

70% isoproponal, ethanol, triclosan (narrow against G-, dissolves the outer membrane

Quaternary Ammonium examples

household cleaners and ammonium chloride (narrow against G+, goes thru cell wall)

What group does Balantidium coli belong to?

Group Ciliophora - moves with cilia

What shape is the nucleus of Balantidium coli?

Bean/bar shaped

How is Balantidium coli transmitted?

Cysts in contaminated food/water

What disease symptom does Balantidium coli cause?

Diarrhea

Is Paramecium pathogenic or free-living?

Free-living - moves with cilia

What group does Entamoeba histolytica belong to?

amoebozoa

What disease symptom does Entamoeba histolytica cause?

Diarrhea

What group does Trichomonas vaginalis belong to?

Archaezoa - moves with flagella

What group does Trypanosoma belong to?

Euglenozoa

Which Trypanosoma species causes African sleeping sickness?

T. brucei - tsetse fly

Which Trypanosoma species causes Chagas disease?

T. cruzi - triatomomine bug

Is Euglena free-living or pathogenic?

free-living and photosynthetic

What disease does Plasmodium cause?

malaria

How can Toxoplasma gondii infection occur?

Ingestion of cysts from cat feces

What major risk does Toxoplasma gondii pose in pregnancy?

Can cross placenta causing birth defects - determined by serological testing

What are yeasts?

unicellular fungi

what are molds made of?

hyphae

what is a mycelium?

mass of hyphae

What is the most common Candida species?

Candida albicans - can overgrow and be opportunistic pathogen

how does candida reproduce

budding

what do molds use for reproduction?

spores

which mold is the source of penicillin?

penicillum - conidia

What disease does Coccidioides immitis cause?

Valley Fever

What type of helminth is Clonorchis sinensis?

Trematode (liver fluke)

What type of helminth is Schistosoma mansoni?

Trematode

What type of helminth is Taenia pisiformis?

Cestode

What type of helminth is Trichinella spiralis?

Nematode

indole test

tryptophan —> indole

red ring after Kovac’s: positive

no color change : negative

TSI slant

yellow slant/yellow butt: ferments multiple sugars

red slant/yellow butt: glucose only

black precipitate: H2S production

starch hydrolysis

clear zone: positive

nitrate reduction

pink after reagents A + B: positive

pink after zinc: negative

clear after zinc: positive

mueller-hinton

kirby-bauer antibiotic testing

sabdex

used for fungi, yeasts, and molds

thiglycollate

determines oxygen requirements

streak plate

isolation of colonies

spread plate

quantity and colony counting

brewer’s jar

anaerobic condition for obligate anaerobe

calibrated loop

0.001 mL used for urine cultures

dilution series

each dilution decreases concentration

counting microbes

colonies x dilution factor 30-300

kirby-bauer

zone of inhibition, sensitive, intermediate, resistant

UV light

high UV - kills microbes more time it’s there and less distance

obligate anaerobe

cannot survive with oxygen - grows at bottom

facultative anaerobe

can use both oxygen and no oxygen - grows throughout but more at top

aerotolerant anaerobe

survive in the presence of oxygen but do not use it for growth - even growth throughout

neutrophil

granulocyte

phagocytosis

eosinophil

granulocyte

helminth defense

basophil

granulocyte

allergic reaction

monocyte

agranulocyte

phagocytosis

lymphocyte

specific immunity

agranulocyte

endospore stain

green endospores and red vegetative cells

halophile + mannitol fermenter

staphylococcus aureus

acid-fast

mycobacterium

acid-fast stain

distinguishes bacteria based on the presence or absence of mycolic acid in their cell wall

endospore former

old Bacillus subtilis

presumptive test

coliforms are lactose fermenters - Most probable number

confirmed test

uses EMB , growth is gram negative and metallic green is lactose fermenters

completed test

morphology of microbe

lysozymes

destroys the peptidoglycan cell wall in gram positive bacteria

MR-VP test

MR: red broth (+) for glucose fermentation (add methyl red)

VP: red ring (+) for neutral waste

only one can be posititve

Durham test

tests for fermentation of one carb (glucose OR lactose)

yellow: (+) for carb fermentation

pink: (-)

bubble: fermentation resulted in gas prod

triple sugar iron slant

tests for carbohydrate fermentation and H2S gas production

contains glucose, lactose, and sucrose, and iron

iron reacts with H2S gas —> black precipitate

TSI slant results

all red/pink slant: (-) for glu, lac, and suc fermentation

pink top/yellow but: (+) for glucose fermentation ONLY

all yellow slant: (+) for glucose fermentation AND sucrose and/or lactose fermentation

Black but: (+) for H2S gas prod (and for glucose fermentation)