Microm 302 Quiz 7

UW

What are the characteristics of streptomyces?

Obligately aerobic, gram pos, filamentous bacteria

What is streptomyces?

Abundant bacteria in soil that give soil its smell and produces antibiotics

What are antibiotics?

Organic metabolites that inhibit/kill other microorganisms

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

Narrow spectrum (limited), and broad spectrum (wide range)

What do streptomyce colonies look like?

Small, hardened white powder, white/grey with darker inside.

Would streptomyces be found on a heated sample?

No because it is vegetative or maybe just not as heat resistant

What is the diffusion zone?

An antibiotic that has spread from the inoculum

What is aerial hyphae?

Occurs in response to nutrient limitation and makes powdery appearance of streptomyces.

What will growth patterns that are and aren't susceptible to antibiotics look like on a plate?

Susceptible will have an effect on the organism and inhibit its growth, and not susceptible will be normal growth.

What is epidemiology?

Branch of public health concerned with identifying the factors that can influence the occurrence and spread of communicable disease

What is serratia marcescens and what does it produce?

Gram-neg bacterium that makes antimicrobial pigment called prodigiosin

What is prodigiosin?

Made by serratia and is antimicrobial that can be orange to brick red color

What is a bacteriophage?

A virus that infect bacteria that require a host to replicate

What are phages made from?

Nucleic acid genome surrounded by capsid

What is a capsid?

Protein coat that surrounds genetic material

What are virions?

Individual phages

What is the lambda bacteriophage?

Its cell receptor is the protein used with E. Coli to transport maltose

What happens if a cell lacks the receptor molecule for a bacteriophage?

The cell is resistant to infection by the bacteriophage

What are the lysis steps of a bacteriophage with a host cell?

Attaches, injects genome, synthesizes new components for virions, those self-assemble, form phage particles, host cell lyses (breaks), virions escape

What will lysis look like in a broth culture?

It will turn from cloudy to clear

What will lysis look like on an agar plate with susceptible bacteria?

Clear spots made by ONE individual virions and these are called plaques

What is a plaque exactly and how it it useful on a plate?

Caused by an individual virion infecting, replicating, and lysing a cell = zone of clearing and each plaque = one virion. So accurate count

What is the titer of a sample?

The concentration of bacteria in a given sample when phages are added to the plate.

How is the titer recorded? (units)

phage/mL or pfu/mL

What are bacteriophages that lyse their hosts called?

virulent phages (or lytic)

Does lysis occur in all hosty cells that are infected by bacteriophages?

Naur

What is the other cycle of bacteriophages that doesn't lyse the host?

Lysogenic cycle

What is the lysogenic cycle?

phage DNA integrates into the host cell chromosome, gets replicated with host genome, and is passed down into its daughter cells

What is a prophage?

When host cell DNA is integrated with bacterial genome

What is a lysogen?

When a host cell is carrying integrated bacterial genome (prophage inside)

What is a temperate phage?

Bacteriophages that can choose the lytic or lysogenic cycle

What would the lysogenic cycle look like on a plate?

Not clear plaque but a slight turbidity since not as many host cells are lysed

How does lambda phages control whether they are lytic?

They turn off genes normally expressed for lytic growth by making lambda repressor protein that binds to sequences in its own DNA and this blocks expression of all prophage genes, including lytic function

Whats up if the lambda repressor protein is present in a cell?

All other phage genes are turned off and the phage remains latent within the host as a prophage. It will repress the expression of any new lambda phage that infects lysogen host.

What happens if there is no lambda repressor protein?

Lytic growth gets expressed

What happens to the lambda repressor protein if the cell is stressed?

It is degraded, so the lytic genes are expressed, so the lytic cycle begins to replicate more phages

What happens if a lysogen is infected with a second phage?

The repressor proteins will prevent expression of any lytic genes from entering = LYSOGEN IS IMMUNE to superinfection

What is superinfection?

When second infection takes place after a first infection

What is lambda vir?

Mutant form of lambda that doesn't have sequence required for binding of the lambda repressor protein, so lytic cycle will be expressed anyway.

What is induction?

When lysogenic cycle turns into lytic cycle when host becomes stressed

Why would you not invert plates?

To prevent mixing

What is agrobacterium tumefaciens and where does it reside?

Plant pathogen that causes crown gall in broad-leaf plants and creates opine prouction and resides in the soil.

How does a plant get a gall?

Agrobacterium tumefaciens enters through a wound or a graft and forms tumor-like growth. Typically near the crown/soil surface.

How is pathogenicity of agrobacterium mediated and what happens?

Uses Ti plasmid that is transferred to plant cell plasmid and is integrated into its genome. This causes uncontrolled growth of plant cells and also makes the plant produce opines as a nutrient source for agrobacterium.

What can occur if bacterium get into the bladder?

UTI

What are common bacteria that cause UTIs?

Own fecal microbiota, E. coli, proteus, pseudomonas, enterococcus, staphylococcus saprophyticus, enterobacter

How many microorganisms are involved in creating a UTI?

Usually only one

What concentration of bacteria in a urine sample will indicate an infection?

10^5/mL

What is MacConkey agar?

Differential and selective medium with lactose and pH indicator.

What will a MacConkey agar plate look like with not/ lactose fermenting colonies?

Yes: Red/purple. Not: colorless

How is MacConkey selective?

Contains dyes and bile salts that inhibit gram-pos organisms and gram-neg cocci

Is blood agar selective and/or differential?

Not selective so it will allow for a broad range of growth. Differential for hemolysis

Which test(s) can you do to find out the species of a gram-pos bacteria in a urine sample?

Catalase for staphylococcus (pos) or enterococcus (neg)

Which test(s) can you do to find out the species of a gram-neg, lactose positive bacteria in a urine sample?

Lactose ferment, tryptone broth, MR-VP, citrate slant, motility agar deep

Which test(s) can you do to find out the species of a gram-neg, lactose negative bacteria in a urine sample?

Oxidase, lactose ferment, glucose ferment, catalase

What does a lactose ferment test tell us?

Will confirm if an organism is lactose fermenting or not

What does tryptone broth test tell us and when can we use it?

Use it if you have gram-neg lactose positive organism. It tests for indole production and E. Coli tests positive.

What does the MR-VP test tell us and when can we use it?

Use it if you have gram-neg lactose positive organism. Tests for pathways to ferment glucose.

E. coli will use a mixed fermentation pathway and products will be pH below 4.5.

Enterobacter and klebisella use butandiol pathway and will produce acetoin fermentation product and less acidic pH.

What does the citrate slant test tell us and when can we use it?

Use it if you have gram-neg lactose positive organism. Used to see if can use citrate as sole nutrient source. Growth is positive, as well as blue color change.

E. coli will be citrate negative

Enterobacter and Klebisella are citrate positive.

What does the motility agar deep test tell us and when can we use it?

Use it if you have gram-neg lactose positive organism. Used to see if organism is motile. An inoculating needle is used.

Enterobacter is motile.

Klebisella is non-motile

What does a catalase tell us and for what?

Positive for organisms that are aerobes and facultative aerobes. Obligate anaerobes are negative.

For gram-neg, lac neg, can be proteus (neg) or pseudomonas (pos)

What does a glucose ferment test tell us and when can we use it?

For gram-neg, lac-neg organisms. Pseudomonas is negative and proteus is positive.

What bacteria causes a sore throat?

Streptococcus pyogenes

What is the lysis of RBC calls?

hemolysis

What will hemolysis look like on blood agar plate?

Clear zone around bacteria

What are the different types of hemolysis?

A-hemolysis - produce greenish due to partial hemolysis.

B-hemolysis - complete lysis of cells

What are some of the normal microbiota of the throat and what are their characteristics?

Streptococcus (a-hemolytic), streptococcus (b-hemolytic), neisseria/moraxella (brown/yellow, kidney bean, maybe hemolytic, oxidase positive), lactobacillus/corynebacterium, canadia, staphylococcus whats gram-pos cocci, bacillius, escherichia, enterobacter)

What are immunoglobulins?

Antibodies that are soluble proteins that are produced by the body as the adaptive immune response

What is the function of antibodies?

Recognize antigens in the body and immobilizing them so they can be destroyed by the immune system

How does a antibody and antigen relationship work?

Very highly specific, only one specific pairing and results in a visible precipitate

Are antibodies poly or bivalent?

Bivalent so will bind to two epitopes

Are antigens poly or bivalent?

Polyvalent

How can we test antibody/gen relationships in a lab?

Use ouchterlony immunoprecipitation by putting samples of antigen/body close together on a plate and seeing if precipitate is made between the samples and this means that the antibody detects the antigen

What is albumin?

carrier protein that is abundant in tissue of mammals but slightly differs between species

How was the antibody serum made for this lab?

Goat injected with antigens from different species to produce antibodies and then blood sample but no RBC, just serum of antibodies

What are staphylococci?

gram-positive cocci on our skin

What types of staphylococci are there?

Staphylococcus epidermis (good, on our skin, gets rid of pathogens), aureus (bad, can cause disease like TSS, pneumonia, food poisoning)

How many people are carriers of S. aureus?

15% are healthy, another 15% are transient carriers but neither have ill effects

What are mannitol salt plates?

Contain nutrient agar, 7.5% NaCl, mannitol, pH indicator. Salt will inhibt bacteria (selective for salt-tolerant), mannitol +pH indicator look for mannitol fermenters = S. aureus

What will mannitol fermentation look like?

Agar turns from pink to yellow around the aureus. (pH is yellow from acid, not red)

What will epidermidis look like on mannitol agar?

little small shiny white colonies

Whats the deal with resistance and aureus?

Used to be susceptible to penicillin now not and all are resistant

What are circular genetic elements called and whats special about them?

R plasmid can can be transferred directly between different bacteria

What is the kirby-baur disc diffusion assay?

Suspension of the organism is spread as a lawn over agar plate. Paper discs with antibiotics are placed in intervals on the plate that will diffuse into the medium and makes a concentration gradient. Zone of inhibition develop around the antibiotic