Microm 302 Quiz 6

UW

What are streptomyces?

Gram-pos, filamentous bacteria that live in the soil and produce geosims and antibiotics

What are geosims?

gives soil its characteristic aroma

What are antibiotics?

Organic metabolites that inhibit or kill other microorganisms

How do antibiotics do their job?

They interfere with an essential cell process (protein/nucleic acid/petidoglycan synthesis)

What two types of antibiotics are there and what do they do?

NARROW-SPECTRUM inhibit/kill limited types of microorganisms. BROAD-SPECTRUM inhibit/kill a wide range of microorganisms

Why wouldn't there be Streptomyces on a heated sample?

They are vegetative cells and will be killed in heat.

What do Streptomyces look like?

Small, look like hardened powder, white/grey, dark center

Why would the morphology of streptomyce change on a different plate?

Depends of the amount of nutrients available to the organism. More nutrient rich plates can make it less "hardened powder, white grey"

What would antibiotic resistance look like on a plate with streptomyces?

Would see both growth in and out of the diffusion zone of the streptomyce

What is the diffusion zone?

Antimicrobial organism has diffused into the space around it, it is clear and can prevent growth of other organisms if not resistant

What would susceptibility look like?

There would be growth outside the diffusion zone, but not inside of it.

What are the three methods of how bacteria can acquire genetic material?

Conjugation, transduction, transformation

What is conjugation?

DNA is transferred by direct cell to cell contact

What is transduction?

bacterial DNA is introduced by a bacteriophage

What is transformation?

Naked DNA is taken up directly from the environment

What is genetic competence?

A bacterium's ability to take up DNA from its environment

What is acinetobacter?

Gram-neg, non-motile rod found in soil and water. It is always naturally competent (can transform at all stages of growth)

When is bacillus naturally competent?

Only competent during the transition from the exponential growth into the stationary phase.

When is E. Coli naturally competent?

Never but is in calcium chloride

What is a genetic marker and what requires it?

Gene encoding an observable trait that's absent in the recipient cell. DNA being transferred requires it

What is a prototroph?

Able to grow on minimal media with a single carbon source

What is an auxotroph?

Organisms that lack the ability to synthesize one or more essential metabolites, so needs to grow in an environment where tryptophan is already present

What should a solution with naked DNA look like and how is it done?

Very slimy and viscous by heating a solution of cells

Would Tsp- grow on TSP agar plate and minimal media plate?

TSY yes, minimal media no.

Would DNA be able to grow on its own in TSY?

No.

Would Tsp+ grow on TSY and minimal media plate?

Yes

Would Trp- and DNase grow on TSY?

Yes because DNase only affects naked DNA, not cells

Would DNA grow on TSY?

No

Would DNA and Trp- cells grow on minimal media?

Yes

Would DNA, DNase, Trp- cells grow on minimal media?

Nope. DNase degrades the DNA so there's no tryptophan to incorporate into the Trp- to grow.

While growth/no growth may be expected, how can you know that there are no mutations/contamination?

You don't. All the other controls will show you and help.

What is transmitted through fecally-contaminated water?

Cholera, typhoid fever, polio, dysentery

How does fecally-contaminated water transmit?

Colonize in intestine of infected person and are excreted in feces

What are indicator organisms?

Bacteria that indicate the possibility of fecal contamination of water source. Ex: E. Coli

How is fecally-contaminated water tested?

test for amount of normal fecal microbiota since actual microbial pathogens are very sparse

What are coliforms?

Gram-neg rods that ferment lactose with the production of gas and acid within 48 hours at 35C

What are examples of coliforms?

E. Coli, Enterobacter, Klebsiella

How do you monitor coliforms?

Most Probable Number test (MPN) is when organisms are put into a broth that only allows for gram-neg rods to grow. Gas production will be seen if positive

Why would you use double-strength lauryl lactose?

If adding a diluted sample (ex. 10mL), it dilutes the broth

What is Lauryl lactose broth?

Selective and differential medium with lactose, tryptone, lauryl sulfate.

What is lauryl sulfate?

Detergent that inhibits gram-neg cocci and gram-pos rods/cocci, so only allows for gram-neg rods to grow. Any gas that is present in the Durham vial is a result of lactose fermentation

What is EMB?

Selective and differential medium with nutrient agar base + lactose, eosin/methylene blue dyes. Allows for gram-neg rods to grow only

What does E. Coli look like on EMB?

Green shiny

What do enterobacter aerogens look like on EMB?

Lighter with dark center and no green sheen

What enzyme helps light production and how?

Bacterial luciferase. It uses O2 and fatty acids

Why do luminescent bacteria help creatures and how?

Allow for symbiotic relationship helping animals attract prey while living in nutrient-dense areas when swallowed

Which are the cells that produce light only at a high density?

Vibrio fischeri

What is quorum sensing?

Quorum sensing involves a self-producted extracellular signal called an autoinducer

What is an autoinducer?

Self-produced extracellular signal molecule that create signal

What are photobacterium cells?

Gram-neg rods that glow

What are Vibrio cells?

Gram-neg rods/curved rods and can glow

What is epidemiology?

Branch of public that identifies the factors that can influence the occurrence and spread of communicable diseases

What is Serratia marcescens?

Gram-neg bacterium that makes an antimicrobial pigment called prodigiosin

What color is prodigiosin and where does it come from?

Comes from Serratia marcescens and is orange to brick red

What is a bacteriophage?

It is a virus that can infect a bacteria and has a nucleic acid genome surrounded by protein coat (capsid)

What are virions?

Individual phages that came from a parent phage (so it's basically a daughter phage)

What does a bacteriophage need to be able to replicate?

Host cell

What types of genomes do phages have?

ssDNA/dsDNA or ssRNA/dsRNA

What does a cell need for a phage to be able to attach to it?

Specific receptors

What does a phage do to a cell?

Exploit it

What does it mean when a cell is resistant?

The cell lacks the receptor molecule, usually due to spontaneous mutation

What happens once a phage particle attaches to a cell?

It injects its genome into it and uses the host cell to replicate it. They self-assemble and exit the cell

What is the lytic cycle?

Phage infection leading to lysis of the cell. Phage attaches, injects DNA, phage DNA replication to make new capsids, host cell is lysed.

What will lysis look like in a culture?

It will turn clear

What is a plaque?

result of a single phage particle infecting one cell, replicating, lysing the cell and enter the nearby surrounding, causing a large clear zone

What does the number of plaques represent and what can we do with it?

Each plaque represents one phage particles, so we can count and calculate the concentration/titer of bacteriophage in a sample

What are the units for phage titer?

cfu/mL or cells/mL of pfu/mL (plaque forming units)

what are cirulet phages?

They invariably lyse host cells (lytic)

What is the lysogenic cycle?

Phage DNA integrates into hosts genome, and replicates along with it and passed down = prophage in a bacteria cell -> lysogen. Repressor protein prevents lytic cycle and can eventually enter the lytic cycle if stressed.

What are temperate phages?

Have the option to be lytic or lysogenic

What is a lysogen?

A host cell that carries a prophage

What is a prophage?

integrated viral DNA

What do temperate phages form?

Slightly turbid areas since they don't lyse

How is the lytic cycle repressed in lambda bacteriophages?

Make lambda repressor protein that binds to its own DNA to stop lytic growth

When does the lytic cycle proceed in lambda bacteriophages?

When repressor is off

What does the lambda repressor protein do?

Represses the lytic cycle from happening for lambda bacteriophages, but also any other lambda phages that enter the cell

Why could there be colonies forming in the plaque?

Areas without the phage infecting the host cells

What is immunity?

When if a second phage enters the phage lysogen, then the repressor proteins will prevent any lytic genes of new entering phage

What is lambda vir?

Mutant form of lambda that lacks the DNA sequences for the binding of the repressor protein, so lytic genes are expressed even in lambda lysogen host

How should you incubate soft agar plates with two organisms on it and why?

NOT inverted since you can mix the two organisms and get skewed results.

What is the name of the plant pathogen capable of causing crown gall in broad-leafed plants?

Agrobacterium tumefaciens

how does Agrobacterium tumefaciens enter plants?

Via wounds or graft

Where does Agrobacterium tumefaciens live and what does it do?

Lives in soil and causes formation of tumor-like growth called a gall typically at plant root crown

What happens once Agrobacterium tumefaciens infects a plant?

Bacterium transfers a portion of the plasmid to plant cell and causes uncontrolled growth, creating a gall and also produces a nutrient source (opines amino acids) that gives them an advantage

What can Agrobacterium tumefaciens be used for?

For genetic engineering to insert desirable genes into the plant (can generate own pesticides)

What is a UTI?

Urinary tract infection caused by bacteria gaining access to the bladder. Usually fecal microbiota and are more common in women since womens' urethra is shorter

What are the most common bacteria that cause UTIs?

E. Coli, proteus, pseudomonas, enterococcus, staphylococcus saprophyticus and enterobacter

How is diagnosis of a UTI done?

Examination and culture of fresh urine sample collected as aseptically as possible to distinguish between UTI causing bacteria and others (noncontaminated)

What is MacConkey agar?

Differential and selective medium with lactose, pH indicator, dyes, and bile salts

What will organisms look like on a MacConkey agar plate?

Lactose fermenters will be red-purple, non-lactose fermenters will be colorless, and inhibit gram positive organisms and gram-neg cocci

What is a blood agar plate?

Non-selective medium that supports growth of many organisms. Can differentiate hemolysis but not very relevant

Which UTI bacterium is gram positive?

Staphylococcus or enterococcus

Which UTI bacterium is gram negative?

E. Coli, enterobacter, klebisella

Which bacterium are gram positive and catalase positive?

Staphylococcus

What does MR-VP test do for gram-neg?

Identifies two different pathways used to ferment glucose

Which glucose fermentation path way do Enterobacter and Klebsiella take (gram-neg)?

Butanediol pathway

What does the citrate slant test do for gram-neg?

Tests for ability to use citrate as energy and carbon source (Klebsiella)

What does the motility agar deep do for gram-neg?

Distinguishes between Enterobacter (motile) and Klebsiella (non-motile)

What are lactose negative gram-neg bacteria and how can you distinguish them??

Pseudonomas (ferments glucose) or proteus (not ferments glucose), by catalase test