Microbio Test 2

Izzo :)

What do microbes need to grow?

• Macronutrients (Need more, CHONPS)

• Micronutrients (Need less, Mg/Ca/Fe/K)

• Growth Factors

Synthetic/Defiant Media

We know the exact composition

Complex Media

1+ portions not known

Selective Media

Component in media (antibiotic, salt) that selects against certain microbes

Enrichment

Adding something to media to increase the growth of your target organism

Differential Media

Something in media leads to visual differentiation of microbes (Ex: Blood Agar)

Methods of Prokaryotic Division

• Binary Fission

• Budding

• Fragmentation

Autolysin

Involved with Prokaryotic Division, makes cuts in PG layer

Fts Z and Fts I Protein

Involved with prokaryotic cell division

I: Attach amino acid tails of NAMs together

Z: Form the ring in the middle of a growing cell

Transglycosylases

Prokaryotic Division: Attach NAG + NAM of adjacent PG molecules

mreB protein

Prokaryotic cell shape determinant. Makes matrix to guide cell shape formation (think wire in paper mache)

Doubling Time

How long is takes a (usually bacterial) population to double

Humans ~20 years, bacteria ~80 minutes

Phases of Bacterial Exponential Growth

• Lag

• Log

• Stationary

• Decline

Lag phase

Occurs right after inoculation. Slow growth as bacteria adjust to conditions.

Log phase

Growing optimally in conditions. Shortest doubling time.

Stationary Phase

Population size levels off. Carrying capacity reached. Death rate=new cell rate.

Decline Phase

Cell death > new cell growth.

Approaches to Growing Bacteria

• Batch Cultures: Limited nutrients determine carrying capacity (agar plate).

• Continuous Cultures: Constant input of fresh media and output of dead cells/waste.

Ways to increase membrane fluidity (opposites decrease)

Less [saturated fatty acids], higher temperature, more sterols

Heat Impacts

• Substrate movement speed increases

• Membrane fluidity increases

  • Fatty Acid stacking lessens => less saturated fatty acids, more sterols => more fluidity

Psychrophiles

Live at 0-20°C

More sterols, less saturated FA

Higher [A-helix]

Mesophiles

Live at 20-40°C

Thermophiles

Live at 40-70°C

Hyperthermophiles

Live at >70°C

Less sterols, more saturated FA

Higher [B-sheet]

Range of pH for known life

0.06-12

Acidophiles

Neutrophiles

Alkaphiles

pH 1-5

pH 5-8

pH 8+

Obligate Aerobes

Must have O2 to respirate

Microaerophiles

Need O2 but O2 also toxic to some processes

Facultative Aerobes/Anaerobes

Can use O2 or something else for respiration

Aerotolerant

Anaerobes for which O2 is not toxic

Obligate Anaerobes

Must use something other than O2 as Terminal Electron Acceptor

Toxic Forms of Oxygen

Superoxides (O2-)

Hydrogen Peroxide (H2O2)

Hydroxides (OH-)

Bacterial methods to counter toxic oxygen variants

Catalase enzyme: H2O2 + H2O2 —> 2H2O + O2

Superoxide Dismutase enzyme: O2- + O2- + 2H+ —> H2O2 + O2

Halophile

Halotolerant

Likes high salt concentration

Doesn’t like high salt but can handle it

Osmophiles

Likes high sugar concentration

Xerophiles

Like dry conditions

Borophiles

Like high pressure

Heterotrophs

Autotrophs

Eat other things

Fix their own carbon

Phototrophs

Chemotrophs

Ultimate source of energy is light

Ultimate source of energy is molecular breakdown

Chemolithotrophy

Can grab and use inorganic molecules

Go draw the entire glycolysis to pyruvate chain

Good Luck :)

Photosystems I and II

Contain light absorbing pigments

Integral proteins in thylakoid membrane

Noncyclic Photophosphorylation

e- that enter eventually leave

Usually produces 1 ATP, 1 NADPH, 1 O2

Cyclic Photophosphorylation

e- get excited from PS(I) and end back in PS(I)

Gain ATP only

Evolutionary trends of Phosphorylation (Light-dependent rxns)

Simple —> complex

Cyclic —> Noncyclic

Nonoxygenic —> oxygenic

Simplest photophosphorylation system (bacteriorhodopsin)

Absorbs light E, uses it to pump e- against gradient, chemiosmosis to make ATP

Second evolutionary step: Simple ETC + Photosystem

Cyclic photophosphorylation

1st ETC

absorbance of p700 in PS(I)

Third evolutionary step: Duplication of PS, noncyclic

Duplication of PS(I), PS(II) still has p700

More ETC components (stops between PS(I) and PSII))

Noncyclic photophosphorylation arises

Full modern setup

PS(II) now has p680

PS(II) can now split H2O

Mitochondria + Chloroplasts

Double Membraned (Gram-)

Plastids

Their own set of circular DNA

Their own ribosomal RNA

Mitochondria has Fts proteins

Methods of Physical Growth Control

Heat

Filtration

High energy waves

Factors affecting heat growth control

Max temp reached

Time spent at heat

Dry vs wet heat

Decimal Reduction Time

Amount of time required to reduce viable bacteria concentration from 100% to 10% (10-fold reduction)

Thermal Death Time

How long at a temperature does it take to kill everything

Autoclave Heat Control

Pressure-induced 121°C for 15min

Pasteurization Heat Control

65°C for 30 minutes (Doesn’t kill everything)

Flash Pasteurization

71°C for 15 seconds

Depth Filters (Size exclusion physical control)

Lay down a filter matrix

Pores are inconsistent but small on average

Membrane filters (Size exclusion physical control)

Chemically synthesized

Pores very consistent

Ex: HEPA (High Efficiency Particulate Air filters)

UV Light (Energy wave physical control)

Damages DNA

Microwaves (Energy wave physical control)

Bursts cells

Variables affecting chemical control

Concentration

Time of exposure

Chemical type

Bacteriostatic Treatment (Chemical control)

# of cells stays constant after treatment

Bacteriolytic (Chemical control)

# of cells decreases after treatment

Bacteriocidal (Chemical control)

# of live cells decreases after treatment

# of total cells stays constant after treatment

Sterilizers

Kill everything including endospores

Disinfectants

Kill everything except endospores

Antiseptics/Sanitizers

Doesn’t kill everything, just reduces numbers

Paul Erlich

Coins “Chemotherapetic” term for chemicals that affect microbes and ignore humans

Develops staining techniques in Koch’s lab

Sulfa drugs (Synthetic)

PABA (precursor to folic acid) analog

Stop microbial nucleotide synthesis via competitive inhibition

Doesn’t affect humans since we get folic acid from diet

Fluoroquinolones

Bind DNA Gyrase (uncoils bacterial DNA)

We don’t have DNA gyrase —> can’t affect us

Natural Antimicrobials

Produced by an organism

Alexander Fleming

Discovered Penicillum chrysogenum - produces penicillin

Streptomyces genus (within Actinobacteria)

Over 600 types of antibiotics from this group of organisms

B-Lactams

Fungal produced

Bind Fts proteins, halting peptidoglycan synthesis

Ex: Penicillin, Ampicillin, Methicillin, Cephalosporin

Penicillin

Cannot cross outer membrance of Gram-

Means it is “narrow spectrum”

Ampicillin

Modified (semisynthetic) penicillin

Can cross outer membrane

Means it is “Broad Spectrum”

Methicillin

Modified (semisynthetic) penicillin

B-lactam ring is more protected

Protects against B-lactamases

Cephalosporin

Resistant to B-lactamases

Made by cephalosporium fungus

Aminoglycosides

Produced by Streptomyces

Bind onto small subunit of ribosome

Ex: “Streptomycin”

Tetracyclines

Made by Streptomyces

Bind small subunit of ribosome

Macrolides

Produced by streptomyces

Bind large subunit of ribosome

Ex: Erythromycin

Cyclic Peptides

Insert into cell membrane

Allow ion transport, disrupting cell function

Novobiocin

Binds + stops DNA Gyrase

Polyoxins

Class of chemotherapeutics against fungi

Can target chitin and chitin synthase

Tolfonate

Class of chemotherapeutics against fungi

Can target ergosterol synthesis

Probiotics

Directly apply live beneficial microbes

Prebiotics

Apply food that beneficial microbes like, enriching their population

Synbiotics

Provide the beneficial microbes and the food they like

Natural Antibiotic Resistance

Resistance to antibiotic due to innate features of the organism

Ex: Gram- bacteria w/ penicillin

Ex: Fungi w/ penicillin

Acquired Resistance

Some change allowing organism to gain resistance

Ex: efflux pumps

Ex: modify the target of the antibiotic

Ex: Break down the antibiotic (B-lactamases)

R-plasmids

The type of plasmid used when an organism acquires a full gene from “plasmid acquisition”

Methods of gaining acquired resistance

Plasmid acquisition

Mutation of existing gene