Microbiology Lab Exam 2- Jones

What indicator organism is used in droplet transmission?

Bacteriophage T7

What is Bacteriophage T7?

a non-pathogenic virus that attacks Escherichia Coli

What is plaque?

It is a zone of clearing on a lawn of bacteria caused by the lysis of the bacteria by the T7 bacteriophage.

What is the basic assumption of each bacterial colony?

Each colony results from a single cell that was plated.

<10^3 (less than 1000 bacteria)

Normal

10^3-10^5(between 1000 and 100,000 bacteria)

Suspicious

>10^5 (greater than 100,000 bacteria)

Infection

Infected urines frequently contain gram ____________ organisms

negative

Why is infected urine especially dangerous in pregnant women?

Because, the gram negative endotoxin may stimulate a premature labor.

What do you do after you diluted your tubes in the enumeration of microorganims in urine lab?

You use a new pipet to transfer 1 ml from your dilutions onto your plate. Start with the 1:100,000 tube and work backwards.

calculation for bacteria/ ml of original urine:

number of colonies on plate X reciprocal of dilution of sample= number of bacteria/ml

aerobic bacteria or aerobes

grow in the presence of free oxygen

anaerobes

grow in the absence of free oxygen

facultative anaerobe

can grow under either condition

strict anaerobes and strict aerobes

can only grow under one condition

microaerophilic

organisms require free oxygen, but at very limited concentrations

What can't strict anaerobes grow in the presence of free oxygen?

because bacterial respiration generates toxic amounts of H2O2 because they lack catalase, which breaks down H2O2.

anaerobic jar

one is used when air is evacuated by a vacuum pump and replaced by an oxygen free gas.

GasPak jar

a GasPak foil envelope is containing substances that generate hydrogen and CO2 is placed in the jar with the cultures

H combines with O to form water

Methylene blue (indicator strip)

colorless in the absence of oxygen and blue in its presence.

thioglycolate broth

a semi-solid medium containing sodium thioglycolate and 0.075% agar. Removes free oxygen

Micrococcus luteus

it grew in air and grows in the top portion of the thioglycolate, an aerobe

plasmid

bacerial DNA that is a non-essential DNA molecules, contain genes that confer antibiotic resistance

How will transformation be accomplished for bacteria??

by using the heat shock method

What does pGLO need in order to cause the organism to glow??

arabinose

Why does pM13 still grow in the presence of ampicillin?

because it has a certain gene to allow it to grow

Why does pGLO grow?

it has the bla gene, which is resistant to ampicillin

What does the bacteria need for it to glow?

It needs GFP gene and arabinose

Results from antibiotic reistance

-both strains grew on TSB (normal plate)

-both strains grew a little on the Kanamycin

-nothing grew on ampicillin

What did MRSA grow on?

All plates except tetracycline

What does Lactobacillus bulgaricus and Streptococcus thermophilus do?

convert milk sugar (lactose) to lactic acid plus minor amounts of other fermentation products.

What does the acidity do?

prevent spoilage

Why is chilling necessary?

to stop acid formation by the starter bacteria at the desired stage

What to do in yogurt experiment?

65C turn off hotplate -> remove at 70C-> 55C put into cups

What should the acidity be in your results of the yogurt??

pH 4.6

Why do we need heat in this yogurt experiment?

So the bacteria can grow and divide

What do the lysozymes in tears and mucous do?

they break down peptidoglycan, which results in the lysis of many Gram + bacteria

What can lysozymes be also found in?

salivs, serum, neutrophils, macrophages, nasal secretions, intestinal mucous, and urine

Bioassay

a standard curve is first constructed, in which the effects of known amounts of a substance are measured using some biological indicator

what kind of plates do you do your lysozyme experiment on?

Tripticase Soy Agar

What will you measure around the filter papers?

zones of growth inhibition

What agar do you use for throat cultures?

blood agar (sterile sheep's blood)

What do many throat pathogens require?

additional CO2

Alpha hemolysis

greenish halo and is the result of the partial breakdown of RBC

Beta hemolysis

complete breakdown that results in a clear halo

gamma hemolysis

no breakdown of RBC

amylases

enzymes that hydrolyze starch

exoenzymes

enzymes secreted from the cell

What do we use to stain to stain the starch?

Iodine solution

What is extracellular amylase indicated by?

halo, or clear yellow zone around the bacteria growth where starch is hydrolyzed

what reaction does citrate cause?

alkaline

What is the pH indicator called for citrate?

bromphenol blue

green citrate

negative

blue

psoitive

What is the sole carbon source in Simmon's citrate?

sodium citrate

what do you use in Carb ferm to trap gas?

inverted vial Durham tube

acid production is signaled by color change

red to yellow (acid) phelo red pH inidicator

Halophiles

grow in 7.5% salt and produce acid (turn yellow)

What is the pH indicator of Mannitol salts?

Phenol Red

positive (can grow) color

yellow

negative (can't grow) color

red (reddish or purplish zones)

Staphylococcus Aureus

Halophile

Eosin Methylene Blue

ihibitors of some gram + microorganisms and indicators of lactose or sucrose fermentation.

Bacteria able to ferment lactose or sucrose produce... (color)

dark colonies with red centers

What does E.Coli produce on EMB

a metallic green sheen

colonies that do not ferment lactose or sucrose(color)...

remain uncolored

polyethylene alcohol inhibits...

gram - bacteria

urease

hydrolyzes urea to yield ammonia and CO2

What color does the indicator turn in urease test when is is positive?

pink

What color does the indicator turn in urease test when is is negative?

yellow/orange

TSI requires you to do what

stab the butt of the tube, and then drag up streaking the slant

What does TSI test for?

carb fermentation, gas production, and hydrogen sulfite production

What does black mean in the TSI tube?

H2S reacts with ferrous sulfate to make ferrous sulfide (just know if H2S is made)

Yellow slant/ yellow butt

lactose fermenters

red slant/ yellow butt

sucrose fermenter

In the anaerobic conditions in the bottom of the tube...

some bacteria use H+ as an electron acceptor and reduce it to hydrogen gas

Carbon dioxide might not show any gas, because...

it is far more soluble in the medium

catalase

an enzyme which breaks down H2O2 yielding O2 and water

what do you do to see if it is a catalse?

add hydrogen peroxide onto the plate and see if bubbles will form

A blood

A antigens, Anti- B, can donate to A and AB, can receive A and O

B blood

B antigens, Anti-A, can donate to B and AB, can receive B and O

AB blood

AB antigens, no antibodies, donate to AB, can receive A, B, O, AB

O blood

no antigens, Anti A and Anti B, donate to A,B, AB, O and receive O

rh -

no clumping

rh +

clumping

Anti A serum agglutination

A and AB

Anti B serum agglutination

B and AB

universal donor

O type

Universal recipient

AB type

coprinus

Club fungi (mushrooms) they have "club" like reproductive structure called a "basidium" (green) which contains "basidiospores" (red)

Trichinella spiralis

pararsite caused by the disease "trichinosis" (pork worm) spiral/worm- like shaped larvae found in muscle

erythroblastosis fetalis

hemolysis of RBC in the fetus/ newborn

RH- mother and RH+ baby, fetal blood causes RH- mother to form antibodies

hemolysis and agglutination

RhoGam