Micro Chapter 3 - Bacteria Pt. 2

Mycobacteria is NOT the same as

Mycoplasma

Mycobacteria has what

peptidoglycan and specialized layer on top

Is Mycobacteria gram + or -?

Gram +

What kind of staining do you have to use for Mycobacteria?

Acid fast staining because it has mycolic acid, which works a lot like wax, so you use steam to force color into it

Mycobacteria leprae

causes leprosy

Mycobacteria tuberculosis

causes tuberculosis (TB)

What color does Mycobacteria show up as in acid fast staining?

Pink because it holds onto carbofushin

Why is Mycobacteria hard to get rid of when they get into the human body?

The mycologic acid protects them against our innate inadaptive immunity

Acid fast staining procedure

Carbol fushin, steam, acid-alcohol, methylene blue (stains the background and any non-acid fast organisms)

What color do acid-fast bacteria stain? Why?

Red, waxy cell wall

What color do non-acid fast bacteria stain?

Blue

Atypical bacteria

not typical bacteria

What makes atypical bacteria - atypical?

They cannot be stained by gram-stain procedures or are too small to hold onto the stain

Atypical bacteria includes

obligate intracellular pathogens

Obligate intracellular pathogens

must grow inside another cell

Rickettsia spp.

Permeable membrane, pleomorphic, hijack nutrients from us

Chlamydia spp.

An obligate intracellular parasite, does not synthesize ATP by itself, hijacks ATP from cell it grows inside of

Mycoplasma spp.

No cell wall, grow in isotonic environments so water can't go in it, one of the smallest bacteria

Hypotonic environment

Means water will go inside

What does peptidoglycan cage bacteria from

Lysing

Protoplast

Name of gram + when cell membrane is the only content left behind on the outside of the cell

Spheroplast

In gram - lysozyme removes most peptidoglycan (β-1,4 bonds) but does not break LPS, so the outer membrane remains → cell still has 2 membranes with peptidoglycan pieces left over in the periplasmic space.

L-form bacteria

Conserve energy by stopping the making of their cell wall in isotonic solution, can't be treated with lysozyme because no cell wall, include some human pathogens

Treponema pallidum is the causative agent of

Syphilis

Helicobacter pylori can cause

Ulcers

How does lysozyme work in hypotonic solution?

Lysozyme digests the cell wall --> H2O enters --> cell lyses

How does lysozyme work in isotonic solution?

Lysozyme digests the cell wall --> cell separates from cell wall --> protoplast left behind (cell membrane)

Capsule

Type of glycocalyx that is thick and organized; protects against phagocytosis, desiccation, and viruses (bacteriophages) + detergents (disrupts cell membrane and causes lysis)

Desiccation

Drying out

Slime layer

Type of glycocalyx that is loosely attached (not organized and looks like snot), helps bacteria perform gliding motility (slow movement)

Glycocalyx function

Surface attachment

Can bacteria with a capsule perform gliding motility?

No

How do cells with a capsule or slime layer appear in a petri dish and why?

Look shiny because they are holding onto water

S layer

Self-assembling glycoprotein found in prokaryotes used for protection, shape, and rigidity, allows for adhesion to surfaces; potential use in nanotechnology

What organisms are S layers found in?

Bacteria and archaea (prokaryotes)

Where is the S layer located in gram +?

On top of the peptidoglycan/cell membrane

Where is the S layer located in gram -?

On top of the LPS, which is on top of peptidoglycan/cell membrane

Pili (Fimbriae)

Short, hair-like structures used for attachment to surfaces and in conjugation

Sex pili

Has conjugate plasmid with information to make sex pili that it transfers to other bacteria through horizontal gene transfer (unidirectional, cannot go back)

Type IV pili (T4P)

Used for twitching motility (slow movement)

Flagella functions

Motility, swarming behavior, attachment, and virulence (having flagella is a sign of virulence)

Monotrichous

One flagella at one end of the cell

Lophotrichous

A bunch of flagella at one or both ends

Anphitrichous

One flagella on each end

Peritrichous

Flagella surrounding whole bacteria

What requires flagella to function?

Swimming, swarming, and spirochete motility

What requires a slime layer to function?

Gliding motility

What requires a type IV pilus to function?

Twitching motility

Bacteria and archaea have what kind of movement?

Directed

Chemotaxis

Flagellar rotation is driven by proton motive force (pmf), bacteria have chemoreceptors that detect changes in chemical concentration, resulting in a "biased random walk"

Chemical attractants

Go towards chemical gradient, ex - glucose

Chemical repellents

Go away from chemical gradient, ex - antibiotics

Phototaxis

Movement towards light done by gas vacuoles

Magnetotaxis

Movement to a magnetic field

How do flagella move?

Rotate like a propeller, use proton motor force for energy

What requires a sex pilus to function?

Conjugation

Propeller

Used in flagellar movement (swimming), the fastest living organisms on Earth, use proton motor force (pmt)

Counterclockwise rotation in swimming

Causes forward motion (run)

Clockwise rotation in swimming

Disrupts run causing cell to stop and tumble

Swarming motility

Done on moist surfaces, type of group bx, peritrichous flagella, commonly done by Pseudomonas species

Spirochete motility

Need a liquid to move, axial fibril (movement looks like a drill, moves whole cell not only flagella), flagella remain in periplasmic space, corkscrew shape (flagella at both ends that face each other and wrap around bacteria), commonly done by Treponema species (syphilis)

Which type of motility is slower

twitching and gliding

What is needed for twitching and gliding motility to work?

Solid surface

Twitching motility

Uses ATP to function, works like climbing up a wall attaching type IV pilus by polymerizing it, then depolymerizing to pull up

Gliding motility

Slime layer makes it easier to glide on hard surface, bacteria rotates on its own axis

Bacterial endospores

Complex, dormant structure, resistant to environmental condition, DNA located in core of spore, only done by gram +

What does the bacterial endospore include?

Calcium (Ca-DPA), small/acid-soluble/DNA-binding proteins (SASPs), dehydrated core, spore coat and exosporium

Small, acid-soluble, DNA-binding proteins (SASPs)

Resists heat, can have DNA and RNA polymerase, which are used when coming back from dormant --> living

What do the spore coat and exosporium do?

Protection

Are spores easy to get rid of?

No, cannot destroy with anything except an autoclave

What are some examples of spore formers?

Bacillus (rods), Clostridium, and Sporosarcina

All spore formers are

gram +, but not all gram + are spore formers

Clostridium tetanai

Tetanus, rods

Sporosarcina Botulinum

Botulism, cocci, no pathogen, associated with improperly canned food

King Tut's Curse

Explorers opened the tomb and disturbed ancient, dormant bacterial/fungal spores. The spores became airborne, were inhaled, reactivated in the lungs, multiplied, and caused fatal infections, killing them

Sporulation

Takes from 8-10 hours, one cell --> one spore, once it starts it can't stop, NOT A MODE OF REPLICATION

Germination

One spore --> one living cell (can't go back to spore afterwards)

What is a big difference between bacterial and fungal spores

Fungal spores ARE used for replication

What is the endospore staining technique called?

Schaeffer-Fulton method

Schaeffer-Fulton method procedure

Malachite green (primary stain), steam, water, Safranin (counterstain)

In endospore staining what color is the spore?

Green

In endospore staining what color is the vegetative cell?

Pink

Vibrio cholerae

Gram -, crescent, no techoic acids, not a spore-forming bacteria, has LPS, has all 3 cytoskeletal proteins, 16S